45 results on '"Chi Wai Tsang"'
Search Results
2. Ophthalmology in the time of COVID-19: experience from Hong Kong Eye Hospital
- Author
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Stephanie S.L. Cheung, Cherie Y.K. Wong, Jason C.K. Chan, Carmen K.M. Chan, N.M. Lam, Hunter K.L. Yuen, Victoria W.Y. Wong, Chi Wai Tsang, and Clement C.Y. Tham
- Subjects
covid-19 ,coronavirus ,sars-cov-2 ,ophthalmology ,infection control ,hong kong ,Ophthalmology ,RE1-994 - Abstract
AIM: To review international guidelines and to share our infection control experience during the coronavirus disease 2019 (COVID-19) pandemic at a tertiary eye centre in Hong Kong. METHODS: Infection control guidelines and recommendations from international ophthalmological bodies are reviewed and discussed. The measures at our hospital were drawn up as per international and local health authorities’ guidelines and implemented with the collaboration of doctors, nurses and administrative staff. RESULTS: The aims of our infection control measures are to 1) minimize cross-infection within the hospital; 2) protect and support hospital staff; 3) ensure environmental control. To minimize the risk of cross-infection, outpatient attendance and elective surgery have been reduced by 40%, and general anesthesia procedures were reduced by 90%. Patients entering the hospital are screened for fever, travel history, contact and cluster history, and COVID-19 related symptoms. To protect and support hospital staff, we ensure provision of adequate personal protective equipment (PPE) and provide clear guidelines on the level of PPE needed, depending on the clinical situation. Other protective measures include provision of work uniforms, easy access to alcohol-based hand rub, opening new lunch areas, implementation of self-monitoring and self-reporting systems, and communication via online education and updates. Finally, environmental control is achieved by ensuring regular disinfection of the hospital premise, enhancing ventilation, and usage of disposable ophthalmic instruments. CONCLUSION: Our multi-pronged approach to infection control is, so far, successful in minimizing infection risks, while allowing the maintenance of essential ophthalmic services.
- Published
- 2020
- Full Text
- View/download PDF
3. Review of Small Gauge Vitrectomy: Progress and Innovations
- Author
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Shaheeda Mohamed, Carl Claes, and Chi Wai Tsang
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Ophthalmology ,RE1-994 - Abstract
Purpose. To summarise the surgical advances and evolution of small gauge vitrectomy and discuss its principles and application in modern vitreoretinal surgery. The advent of microincisional vitrectomy systems (MIVS) has created a paradigm shift away from twenty-gauge vitrectomy systems, which have been the gold standard in the surgical management of vitreoretinal diseases for over thirty years. Advances in biomedical engineering and surgical techniques have overcome the technical hurdles of shifting to smaller gauge instrumentation and sutureless surgery, improving surgical capabilities and expanding the indications for MIVS.
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- 2017
- Full Text
- View/download PDF
4. Review on the Safety and Efficacy of Brolucizumab for Neovascular Age-Related Macular Degeneration From Major Studies and Real-World Data
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Nishant V. Radke, Shaheeda Mohamed, Richard B. Brown, Ilyana Ibrahim, Jay Chhablani, Hivam V. Amin, Chi-Wai Tsang, Marten E. Brelen, Nikhil S. Raichand, Dong Fang, Shaochong Zhang, Hong Dai, Guy Li Jia Chen, Chui Ming Gemmy Cheung, Seenu M. Hariprasad, Taraprasad Das, and Dennis S.C. Lam
- Subjects
Ophthalmology ,General Medicine - Published
- 2023
5. Multimodal imaging features of choroidal metastasis of non-small-cell lung cancer: a case report
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Simon KH Szeto, Shaheeda Mohamed, Chi Wai Tsang, Timothy YY Lai, Vivian WK Hui, and Carmen KM Chan
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General Medicine - Published
- 2022
6. Case Report: Retinal vasculitis in two adolescents after COVID-19 vaccination
- Author
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Shaheeda, Mohamed, Carmen Km, Chan, Chi Wai, Tsang, Simon Kh, Szeto, Angie Hc, Fong, Jason Ck, Chan, and Cherie Yk, Wong
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Ophthalmology ,Immunology and Allergy - Abstract
To report two cases of bilateral retinal vasculitis in adolescents following COVID-19 vaccination.Case report. We report the first two cases of retinal vasculitis in adolescents following COVID-19 vaccinations. Both patients received recent second-dose COVID-19 vaccinations (7 weeks and 4 weeks respectively), and presented with bilateral retinal vasculitis and vitritis. Investigations did not reveal other causes of retinal vasculitis. Both patients' retinal vasculitis settled with a short course of oral prednisolone.Although rare, the temporal association between vaccination, bilateral eye involvement, and the absence of alternative infective or inflammatory causes, makes this a plausible etiology. mRNA vaccinations may cause an autoimmune reaction via host antigenic mimicry, and systemic vasculitis has previously been described. We believe that a short interval between COVID-19 vaccination doses might be a risk factor for the development of retinal vasculitis in adolescents, and clinicians should be aware to elicit vaccination history.
- Published
- 2022
7. Optical Coherence Tomography Angiography Compared with Multimodal Imaging for Diagnosing Neovascular Central Serous Chorioretinopathy
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Shaheeda Mohamed, Fanny Yip, Linbin Zhou, Chi Pui Pang, Danny Siu-Chun Ng, Wee Min Teh, Mary Ho, Marten E. Brelen, Timothy Y Y Lai, Li Jia Chen, Haoyu Chen, and Chi Wai Tsang
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Indocyanine Green ,medicine.medical_specialty ,genetic structures ,Multimodal Imaging ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Ophthalmology ,medicine ,Humans ,Prospective Studies ,Fluorescein Angiography ,Retrospective Studies ,030304 developmental biology ,0303 health sciences ,medicine.diagnostic_test ,Receiver operating characteristic ,Choroid ,business.industry ,Fundus photography ,Retinal ,Fluorescein angiography ,Choroidal Neovascularization ,eye diseases ,Confidence interval ,Serous fluid ,Cross-Sectional Studies ,Choroidal neovascularization ,Central Serous Chorioretinopathy ,chemistry ,Angiography ,030221 ophthalmology & optometry ,sense organs ,medicine.symptom ,business ,Tomography, Optical Coherence - Abstract
PURPOSE To assess the diagnostic accuracy of optical coherence tomography angiography (OCTA) compared with multimodal imaging for choroidal neovascularization (CNV) in central serous chorioretinopathy (CSC) eyes and to determine the features that predicted CNV. DESIGN Prospective cross-sectional study. METHODS Consecutive CSC patients were recruited from retina clinic. The reference standard for CNV was determined by interpretation of multimodal imaging with OCTA, structural OCT line scan, fluorescein angiography (FA), indocyanine green angiography (ICGA), ultra-widefield fundus photography and fundus autofluorescence (FAF). Two independent masked graders examined OCTA without FA and ICGA to diagnose CNV. Univariate and multivariate analyses were performed to evaluate factors associated with CNV. RESULTS CNV was detected in 69 eyes in 64 out of 277 CSC patients according to reference standard. The two masked graders who examined OCTA had sensitivity of 81.2% (95% Confidence Interval [CI], 71.9%-90.4%) and 78.3% (95% CI, 68.5%-88.0%), specificity of 97.3% (95% CI, 95.9%-98.8%) and 96.2% (95% CI, 94.5%-98.0%), positive predictive values of 82.4% (95% CI, 73.3%-91.4%) and 76.1% (95% CI, 66.1%-86.0%), and negative predictive values of 97.1% (95% CI, 95.6%-98.7%) and 96.7% (95% CI, 95.0%-98.3%). Their mean area under the receiver operating characteristic curve (AUC) was 0.88 with good agreement (Kappa coefficient 0.80 [95% CI, 0.72-0.89]). Flat irregular pigment epithelial detachment on structural OCT, neovascular network on OCTA and ill-defined late leakage on FA significantly correlated with CNV in CSC from multiple regression (P CONCLUSIONS There is discordance between OCTA and multimodal imaging in diagnosing CNV in CSC. This study demonstrated the caveats in OCTA interpretation, such as small extrafoveal lesions and retinal pigment epithelial alterations. Comprehensive interpretation of OCTA with dye angiography and structural OCT is recommended.
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- 2021
8. Massive retinal infiltrates as the presenting sign of chronic myeloid leukemia: Clinical and imaging features of leukemic retinopathy
- Author
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Carmen K M Chan, Chi Wai Tsang, Simon Szeto, and Shaheeda Mohamed
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Pathology ,medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Myeloid leukemia ,Retinal ,General Medicine ,medicine.disease ,Ophthalmology ,chemistry.chemical_compound ,Optical coherence tomography ,chemistry ,Feature (computer vision) ,hemic and lymphatic diseases ,medicine ,business ,Retinopathy ,Sign (mathematics) - Abstract
Purpose: To describe the clinical and optical coherence tomography (OCT) features of two cases with bilateral diffuse retinal infiltrates as the only presenting feature of chronic myeloid leukemia (CML) on initial diagnosis and upon relapse. Methods: We reported two patients with CML, one at initial diagnosis and one in remission who presented with bilateral subacute visual impairment. Fundal examination revealed bilateral symmetrical leukostatic appearance with increased vascular tortuosity, diffuse retinal infiltrates with size up to 6 disk diameters, retinal hemorrhages, and Roth’s spots. OCT showed multiple intra-retinal hyper-reflective foci corresponding to intra-retinal hemorrhages, and outer retinal hyper-reflective foci in area corresponding to retinal infiltrate. The different retinal layers were relatively preserved and distinguishable. Results: White cell count (WCC) were elevated in both patients ranging from 544 to 810 × 109/L. Bone marrow biopsy confirmed the diagnosis of CML in the patient without prior diagnosis and relapse of CML in another patient. Cytogenetic test detected Abelson murine leukemia (ABL) – breakpoint cluster region (BCR) fusion transcript in both cases. Both patients were started on oral imatinib, subsequently WCC returned to within normal values in both cases. Vision and OCT abnormalities improved and reduction in retinal hemorrhages and infiltrates were observed in follow up. Conclusion: This report highlights the important role of ophthalmologists and detailed fundus examination in making a prompt diagnosis of leukemia in patients with visual complaints. Appropriate systemic investigation and hematologist referrals for prompt treatment of CML may improve survival rate and preserve vision.
- Published
- 2021
9. Anomaly detection of train wheels utilizing short-time Fourier transform and unsupervised learning algorithms
- Author
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Ting Hei Wan, Chi Wai Tsang, King Hui, and Edward Chung
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Artificial Intelligence ,Control and Systems Engineering ,Electrical and Electronic Engineering - Published
- 2023
10. Applications of reinforcement learning in an open railway access market price negotiation.
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Shun King Wong, Chi Wai Tsang, and Tin-Kin Ho
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- 2008
- Full Text
- View/download PDF
11. Schedule Coordination through Negotiation between Train Service Providers in an Open Railway Access Market.
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Chi Wai Tsang and Tin-Kin Ho
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- 2006
- Full Text
- View/download PDF
12. Ophthalmology in the time of COVID-19: experience from Hong Kong Eye Hospital
- Author
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Chi Wai Tsang, Carmen K M Chan, Jason C. K. Chan, Clement C Y Tham, Cherie Y K Wong, Victoria W. Y. Wong, Stephanie S L Cheung, N M Lam, and Hunter Kwok Lai Yuen
- Subjects
Covid-19 And Ophthalmology ,business.industry ,Control (management) ,coronavirus ,Attendance ,Disease cluster ,medicine.disease ,infection control ,sars-cov-2 ,03 medical and health sciences ,Ophthalmology ,0302 clinical medicine ,covid-19 ,lcsh:Ophthalmology ,Work (electrical) ,lcsh:RE1-994 ,Pandemic ,030221 ophthalmology & optometry ,medicine ,Infection control ,Medical emergency ,Elective surgery ,hong kong ,business ,Personal protective equipment - Abstract
Aim To review international guidelines and to share our infection control experience during the coronavirus disease 2019 (COVID-19) pandemic at a tertiary eye centre in Hong Kong. Methods Infection control guidelines and recommendations from international ophthalmological bodies are reviewed and discussed. The measures at our hospital were drawn up as per international and local health authorities' guidelines and implemented with the collaboration of doctors, nurses and administrative staff. Results The aims of our infection control measures are to 1) minimize cross-infection within the hospital; 2) protect and support hospital staff; 3) ensure environmental control. To minimize the risk of cross-infection, outpatient attendance and elective surgery have been reduced by 40%, and general anesthesia procedures were reduced by 90%. Patients entering the hospital are screened for fever, travel history, contact and cluster history, and COVID-19 related symptoms. To protect and support hospital staff, we ensure provision of adequate personal protective equipment (PPE) and provide clear guidelines on the level of PPE needed, depending on the clinical situation. Other protective measures include provision of work uniforms, easy access to alcohol-based hand rub, opening new lunch areas, implementation of self-monitoring and self-reporting systems, and communication via online education and updates. Finally, environmental control is achieved by ensuring regular disinfection of the hospital premise, enhancing ventilation, and usage of disposable ophthalmic instruments. Conclusion Our multi-pronged approach to infection control is, so far, successful in minimizing infection risks, while allowing the maintenance of essential ophthalmic services.
- Published
- 2020
13. Multimodal imaging features of choroidal metastasis of non-small-cell lung cancer: a case report.
- Author
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Szeto, Simon K. H., Mohamed, Shaheeda, Chi Wai Tsang, Lai, Timothy Y. Y., Hui, Vivian W. K., and Chan, Carmen K. M.
- Subjects
NON-small-cell lung carcinoma ,CANCER diagnosis ,OPTICAL coherence tomography ,BIOFLUORESCENCE ,RETINAL detachment - Abstract
We describe multimodal imaging features of right eye choroidal metastasis of non-small-cell lung cancer in a 25-year-old woman. This case report highlights the importance of multimodal imaging and liquid biopsy in making the diagnosis of choroidal metastasis. Spectral domain optical coherence tomography showed a dome-shaped choroidal elevation with subretinal fluid and subretinal hyper-reflective foci. Fundus autofluorescence showed hyper-autofluorescence with alternating spots of hypo-autofluorescence. Fluorescein angiography showed hypofluorescence followed by diffuse and pin-point leakage. Indocyanine green angiography showed a hypofluorescence lesion. The patient was initially misdiagnosed as having choroiditis and treated with oral corticosteroid. However, the exudative retinal detachment progressed and optic disc edema developed. The working diagnosis was thus shifted towards choroidal neoplasm. Positron emission tomography and lung biopsy confirmed the diagnosis of metastatic non-small-cell lung cancer. Blood-based comprehensive genomic profiling detected a rare epidermal growth factor receptor mutation. Target therapy with osimertinib achieved good oncological response. Vision improved to 6/7.5, and the choroidal lesion and subretinal fluid regressed. At 1-year followup, the patient had no systemic or ocular relapse. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
14. A novel technique for 27-gauge forceps assisted transcleral refixation of dislocated CZ70BD intraocular lens
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Angie Fong, Chi Wai Tsang, and Lai Ting Yip
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Pars plana ,medicine.medical_specialty ,genetic structures ,business.industry ,medicine.medical_treatment ,Forceps ,Retinal detachment ,Intraocular lens ,Vitrectomy ,General Medicine ,medicine.disease ,eye diseases ,Ophthalmology ,medicine.anatomical_structure ,Refixation ,medicine ,sense organs ,business ,Sclerostomy ,Prolene - Abstract
PURPOSE To report a novel technique for refixation of dislocated CZ70BD intraocular lens (IOL). METHODS Posterior vitrectomy is performed with 23 or 25-gauge pars plana vitrectomy system with chandelier illumination. One needle of a double-arm 9-O prolene needle is passed through the sclera 1.5mm post-limbus. The needle is retrieved through the corneal paracentesis using a 27G needle and the suture is then cut. The suture end is passed through the eyelet of the dislocated CZ70BD IOL inside the vitreous cavity. This is aided with a pair of 27G MaxGrip forceps, which is inserted through a 27G sclerostomy site at the intended scleral outlet. After passing suture through the eyelet, the suture is pulled out at the 27G sclerostomy site and knot is tied and rotated. Similar procedure is performed for the second haptic if necessary. RESULTS Seven eyes were successfully operated on using this technique with a mean follow up of 12.4 months. There was significant improvement in best corrected visual acuity (BCVA) after the operation (p=0.016). Postoperative IOL centration and alignment were satisfactory. One patient developed macula-on retinal detachment one month after the operation, which was successfully repaired without loss in BCVA. CONCLUSION The described novel technique is effective for refixation of dislocated CZ70BD IOL.
- Published
- 2021
15. A Multicenter Study on the Long-term Outcomes of Half-dose Photodynamic Therapy in Chronic Central Serous Chorioretinopathy
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Vesta C.K. Chan, Fiona O. J. Luk, Malini Bakthavatsalam, Alvin L. Young, Chi Wai Tsang, Marten E. Brelen, Danny Siu-Chun Ng, and Frank H. P. Lai
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Adult ,Indocyanine Green ,Male ,0301 basic medicine ,medicine.medical_specialty ,Porphyrins ,Visual acuity ,genetic structures ,medicine.medical_treatment ,Visual Acuity ,Photodynamic therapy ,Chronic central serous chorioretinopathy ,Serous Retinal Detachment ,03 medical and health sciences ,0302 clinical medicine ,Recurrence ,medicine ,Humans ,Fluorescein Angiography ,Coloring Agents ,Aged ,Retrospective Studies ,Aged, 80 and over ,Photosensitizing Agents ,medicine.diagnostic_test ,business.industry ,Verteporfin ,Retrospective cohort study ,Middle Aged ,Prognosis ,Fluorescein angiography ,eye diseases ,Surgery ,Ophthalmology ,030104 developmental biology ,Central Serous Chorioretinopathy ,Photochemotherapy ,Multicenter study ,Chronic Disease ,030221 ophthalmology & optometry ,Female ,medicine.symptom ,business ,Tomography, Optical Coherence ,Follow-Up Studies ,medicine.drug - Abstract
To investigate long-term efficacy and prognostic factors of half-dose photodynamic therapy (PDT) in chronic central serous chorioretinopathy (CSCR).Retrospective multicenter interventional case series.Patients with chronic CSCR undergoing half-dose PDT between 2005 and 2011 were reviewed. Main outcome measures included resolution of serous retinal detachment (SRD) with single PDT, change in best-corrected visual acuities (BCVAs), and recurrence rate of CSCR at 36 months after PDT. Prognostic factors of visual outcome and recurrence of CSCR after PDT were identified with multivariate regression analysis.A total of 136 eyes of 123 patients were followed up for 57.7 ± 16.2 months. At 36 months after PDT, 132 eyes (97.1%) achieved complete resolution of SRD with single PDT and 4 eyes (2.9%) had CSCR recurrence. The mean logMAR BCVA improved from 0.36 ± 0.29 (Snellen equivalent 20/46; range: 0.1-1.2) at baseline to 0.15 ± 0.23 at 36 months (Snellen equivalent 20/28; range: 0.1-1.5; P.001) and 0.16 ± 0.24 (Snellen equivalent: 20/29; range: 0.1-1.5; P.001) at final follow-up. Forty-four eyes (32.4%) had ≥3 lines of BCVA gain while 5 eyes (3.7%) had ≥3 lines of BCVA loss at 36 months after PDT. Nine eyes (6.6%) developed CSCR recurrence at final follow-up. Baseline BCVA was significantly associated with the BCVA (P = .009) and the improvement in BCVA (P .001) at final follow-up. History of bilateral CSCR was significantly associated with CSCR recurrence at final follow-up (P = .036; odds ratio = 15.84, 95% confidence interval = 1.20-208.32). Eight eyes (5.9%) had complications related to PDT.Chronic CSCR patients treated with half-dose PDT can achieve long-term stable visual acuity and resolution of SRD. Patients with chronic CSCR are recommended to undergo half-dose PDT before they have significant visual deterioration. Patients with bilateral CSCR are more likely to develop CSCR recurrence after half-dose PDT.
- Published
- 2016
16. Advances of optical coherence tomography in myopia and pathologic myopia
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Carol Y. Cheung, Jason C. S. Yam, Marten E. Brelen, Fiona O. J. Luk, Timothy Y Y Lai, Chi Wai Tsang, Shaheeda Mohamed, and Danny Siu-Chun Ng
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0301 basic medicine ,Posterior Eye Segment ,medicine.medical_specialty ,genetic structures ,Posterior pole ,Glaucoma ,Posterior vitreous detachment ,03 medical and health sciences ,0302 clinical medicine ,Ophthalmology ,Correspondence ,Myopia ,medicine ,Humans ,business.industry ,medicine.disease ,eye diseases ,Visual field ,030104 developmental biology ,medicine.anatomical_structure ,Myopia, Degenerative ,030221 ophthalmology & optometry ,Optic nerve ,Maculopathy ,Optometry ,sense organs ,Choroid ,business ,Tomography, Optical Coherence - Abstract
The natural course of high-axial myopia is variable and the development of pathologic myopia is not fully understood. Advancements in optical coherence tomography (OCT) technology have revealed peculiar intraocular structures in highly myopic eyes and unprecedented pathologies that cause visual impairment. New OCT findings include posterior precortical vitreous pocket and precursor stages of posterior vitreous detachment; peripapillary intrachoroidal cavitation; morphological patterns of scleral inner curvature and dome-shaped macula. Swept source OCT is capable of imaging deeper layers in the posterior pole for investigation of optic nerve pits, stretched and thinned lamina cribrosa, elongated dural attachment at posterior scleral canal, and enlargement of retrobulbar subarachnoid spaces. This has therefore enabled further evaluation of various visual field defects in high myopia and the pathogenesis of glaucomatous optic neuropathy. OCT has many potential clinical uses in managing visual impairing conditions in pathologic myopia. Understanding how retinal nerve fibers are redistributed in axial elongation will allow the development of auto-segmentation software for diagnosis and monitoring progression of glaucoma. OCT is indispensable in the diagnosis of various conditions associated with myopic traction maculopathy and monitoring of post-surgical outcomes. In addition, OCT is commonly used in the multimodal imaging assessment of myopic choroidal neovascularization. Biometry and topography of the retinal layers and choroid will soon be validated for the classification of myopic maculopathy for utilization in epidemiological studies as well as clinical trials.
- Published
- 2016
17. A 12-year review on the aetiology and surgical outcomes of paediatric rhegmatogenous retinal detachments in Hong Kong
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P P Yip, A H Fong, Chi Wai Tsang, and T Y Kwok
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Male ,medicine.medical_specialty ,Visual acuity ,Adolescent ,genetic structures ,Visual Acuity ,Dermatitis, Atopic ,Ophthalmic pathology ,Eye injuries ,Neuro-ophthalmology ,03 medical and health sciences ,Eye Injuries ,Postoperative Complications ,0302 clinical medicine ,Endophthalmitis ,Risk Factors ,Vitrectomy ,Ophthalmology ,medicine ,Humans ,Eye Abnormalities ,Child ,Retrospective Studies ,business.industry ,Retinal Detachment ,Infant ,Retinal detachment ,Retrospective cohort study ,Consecutive case series ,medicine.disease ,eye diseases ,Scleral Buckling ,Child, Preschool ,Myopia, Degenerative ,Clinical Study ,030221 ophthalmology & optometry ,Hong Kong ,Female ,medicine.symptom ,business ,030217 neurology & neurosurgery ,Follow-Up Studies - Abstract
To evaluate the aetiology, clinical features, and surgical outcomes of paediatric rhegmatogenous retinal detachments (RRD) in Hong Kong.Patients and methodsThis is a retrospective consecutive case series of all patients aged 18 or under who underwent primary retinal detachment repair in the Hong Kong Eye Hospital from January 2000 to December 2012.ResultsForty-nine eyes of 47 patients were included. The mean age was 14, and the mean follow-up duration was 6.2 years. The most common aetiology for RRD was idiopathic (28.6%), followed by high myopia (24.5%), atopic dermatitis (AD) (18.4%), congenital and developmental abnormalities (16.3%), trauma (8.2%), and intraocular inflammation (4.1%). The mean preoperative visual acuity was LogMAR 1.0±0.8 (Snellen equivalent 6/60). The primary anatomical success rate in this series was 65.3%, and the final anatomical success rate was 85.7%. The mean postoperative visual acuity was LogMAR 0.9±1.2 (Snellen equivalent 6/48). Patients with congenital and developmental abnormalities or AD had worse anatomical and functional outcomes than patients who had no predisposing factor or high myopia.The primary and overall anatomical success rates in our series were comparable with existing literature. High myopia is the most commonly identifiable risk factor in Hong Kong and AD is associated with a higher re-detachment rates and a poor visual outcome.
- Published
- 2015
18. The cytotoxic mechanisms of disulfiram and copper(ii) in cancer cells
- Author
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Chi Wai Tsang, Peng Liu, Bin He, Angel L. Armesilla, Zhipeng Wang, Patricia Erebi Tawari, Weiguang Wang, Mohammad Najlah, Christopher F McConville, and Vinodh Kannappan
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chemistry.chemical_classification ,Reactive oxygen species ,Chemistry ,Health, Toxicology and Mutagenesis ,Kinetic analysis ,In vitro cytotoxicity ,chemistry.chemical_element ,Pharmacology ,Toxicology ,Copper ,Cancer cell ,Disulfiram ,medicine ,Cytotoxic T cell ,Cytotoxicity ,medicine.drug - Abstract
The anticancer activity of disulfiram (DS) is copper(ii) (Cu)-dependent., The anticancer activity of disulfiram (DS) is copper(ii) (Cu)-dependent. This study investigated the anticancer mechanisms of DS/Cu using in vitro cytotoxicity and metabolic kinetic analysis. Our study indicates that DS/Cu targets cancer cells by the combination of two types of actions: (1) instant killing executed by DS/Cu reaction generated reactive oxygen species; (2) delayed cytotoxicity introduced by the end product, DDC-Cu. Nanoencapsulation of DS might shed light on repositioning of DS into cancer treatment.
- Published
- 2015
19. Classification of Exudative Age-Related Macular Degeneration With Pachyvessels on En Face Swept-Source Optical Coherence Tomography
- Author
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Chi Wai Tsang, Danny Siu-Chun Ng, Marten E. Brelen, Fang Yao Tang, Carol Y. Cheung, Timothy Yuk-Yau Lai, Malini Bakthavatsalam, Gemmy Chu-Ming Cheung, Frank H. P. Lai, and Tien Yin Wong
- Subjects
0301 basic medicine ,Male ,medicine.medical_specialty ,Visual acuity ,Fundus Oculi ,Visual Acuity ,Hemodynamics ,Retinal Pigment Epithelium ,03 medical and health sciences ,0302 clinical medicine ,Vascularity ,Optical coherence tomography ,Ophthalmology ,medicine ,Humans ,Fluorescein Angiography ,Aged ,Retrospective Studies ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Cortical blindness ,Reproducibility of Results ,Retinal Vessels ,Odds ratio ,Middle Aged ,Exudative age-related macular degeneration ,medicine.disease ,eye diseases ,Confidence interval ,030104 developmental biology ,Cross-Sectional Studies ,030221 ophthalmology & optometry ,Wet Macular Degeneration ,Female ,sense organs ,medicine.symptom ,business ,Tomography, Optical Coherence ,Follow-Up Studies - Abstract
Purpose The purpose of this study was to classify exudative maculopathy by the presence of pachyvessels on en face swept-source optical coherence tomography (SSOCT). Methods Consecutive patients with signs of exudative maculopathy underwent SSOCT, fluorescein and indocyanine green angiography (ICGA), ultra-widefield fundus color photography, and autofluorescence examinations. Images were analyzed in a masked fashion by two sets of four examiners in different sessions: (1) the presence of pachyvessels in en face OCT and (2) features of exudative maculopathy in conventional imaging modalities. Quantitative data obtained were subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI), which was the ratio of choroidal vessels lumen area to a specified choroidal area from binarized cross-sectional OCT scans. Results Pachyvessels was observed in 38 (52.1%) of 73 eyes. The pachyvessels group was associated with younger age (69.1 ± 9.4 years, odds ratio [OR] = 0.95, 95% confidence interval [95% CI] = 0.90-0.97, P = 0.04), presence of polypoidal lesions (OR = 3.27, 95% CI = 1.24-8.62, P = 0.01), increased SFCT (OR = 1.08, 95% CI = 1.02-1.14, P < 0.01), and increased CVI (65.4 ± 5.3, OR = 1.12, 95% CI = 1.02-1.23, P = 0.01). In multivariate regression, CVI significantly correlated with pachyvessels (OR = 1.24, 95% CI = 1.03-1.55, P = 0.04). Conclusions Exudative maculopathy could be classified based on differences in choroidal vasculature morphology. Current results implied that choroidal hemodynamics may be relevant to variable natural history and treatment response in neovascular AMD and polypoidal choroidal vasculopathy.
- Published
- 2017
20. Choroidal structures in polypoidal choroidal vasculopathy, neovascular age-related maculopathy, and healthy eyes determined by binarization of swept source optical coherence tomographic images
- Author
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Marten E. Brelen, Danny Siu-Chun Ng, Fang Yao Tang, Chi Wai Tsang, Carol Y. Cheung, Frank H. P. Lai, Timothy Yuk-Yau Lai, and Malini Bakthavatsalam
- Subjects
0301 basic medicine ,Male ,medicine.medical_specialty ,genetic structures ,Fundus Oculi ,Visual Acuity ,Lumen (anatomy) ,Disease pathogenesis ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,Vascularity ,Polyps ,Optical coherence tomography ,Ophthalmology ,medicine ,Humans ,Macula Lutea ,Fluorescein Angiography ,Aged ,Retrospective Studies ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Choroid ,Retinal Vessels ,Mean age ,Axial length ,Macular degeneration ,Middle Aged ,medicine.disease ,eye diseases ,Sensory Systems ,Choroidal Neovascularization ,Age-related maculopathy ,030104 developmental biology ,Cross-Sectional Studies ,030221 ophthalmology & optometry ,Wet Macular Degeneration ,Female ,sense organs ,medicine.symptom ,business ,Tomography, Optical Coherence ,Follow-Up Studies - Abstract
To evaluate quantitatively the choroidal vascularity in polypoidal choroidal vasculopathy (PCV) and neovascular age-related macular degeneration (AMD) patients compared to healthy controls. All eyes underwent swept source optical coherence tomography (OCT), and choroidal images were binarized into blood vessels lumen and stroma. The choroidal vascular index (CVI) was defined as the ratio of luminal area (LA) over total choroidal area of the subfoveal region with a width of 1500 μm. The study included 73 patients with neovascular AMD or PCV with mean ± standard deviation (SD) age of 71.8 ± 9.3 years, which was older than the mean age of 65.1 ± 10.8 years of 72 healthy eyes from control group (p
- Published
- 2016
21. Train service timetabling in railway open markets by particle swarm optimisation
- Author
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K. S. Kwan, Tin Kin Ho, K. H. Ip, and Chi Wai Tsang
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Schedule ,Service (systems architecture) ,Operations research ,Computer science ,media_common.quotation_subject ,General Engineering ,Swarm behaviour ,Particle swarm optimization ,Computer Science Applications ,Artificial Intelligence ,Open market operation ,Customer satisfaction ,Quality (business) ,Intelligent transportation system ,Simulation ,media_common - Abstract
Railway timetabling is an important process in train service provision as it matches the transportation demand with the infrastructure capacity while customer satisfaction is also considered. It is a multi-objective optimisation problem, in which a feasible solution, rather than the optimal one, is usually taken in practice because of the time constraint. The quality of services may suffer as a result. In a railway open market, timetabling usually involves rounds of negotiations amongst a number of self-interested and independent stakeholders and hence additional objectives and constraints are imposed on the timetabling problem. While the requirements of all stakeholders are taken into consideration simultaneously, the computation demand is inevitably immense. Intelligent solution-searching techniques provide a possible solution. This paper attempts to employ a particle swarm optimisation (PSO) approach to devise a railway timetable in an open market. The suitability and performance of PSO are studied on a multi-agent-based railway open-market negotiation simulation platform.
- Published
- 2012
22. Train Schedule Coordination at an Interchange Station Through Agent Negotiation
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Chi Wai Tsang, K. H. Ip, and Tin Kin Ho
- Subjects
Schedule ,Engineering ,Process management ,Operations research ,business.industry ,media_common.quotation_subject ,Transportation ,Negotiation ,Software agent ,Rail transportation ,Conflict management ,business ,Civil and Structural Engineering ,media_common - Abstract
In open railway markets, coordinating train schedules at an interchange station requires negotiation between two independent train-operating companies to resolve their operational conflicts. This paper models the stakeholders as software agents and proposes an agent negotiation model to study their interaction. Three negotiation strategies have been devised to represent the possible objectives of the stakeholders, and they determine the behavior of the stakeholders in proposing offers to other stakeholders. Empirical simulation results confirm that the use of the proposed negotiation strategies lead to outcomes that are consistent with the objectives of the stakeholders.
- Published
- 2011
23. Service bid comparisons by fuzzy ranking in open railway market timetabling
- Author
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Chi Wai Tsang, Tin Kin Ho, and K. H. Ip
- Subjects
Service (business) ,Service quality ,Operations research ,Computer science ,media_common.quotation_subject ,General Engineering ,Service provider ,Track (rail transport) ,Computer Science Applications ,Negotiation ,Artificial Intelligence ,Order (exchange) ,Intelligent transportation system ,media_common - Abstract
In an open railway access market, the Infrastructure Provider (IP), upon the receipts of service bids from the Train Service Providers (TSPs), assigns track access rights according to its own business objectives and the merits of the bids; and produces the train service timetable through negotiations. In practice, IP chooses to negotiate with the TSPs one by one in such a sequence that IP optimizes its objectives. The TSP bids are usually very complicated, containing a large number of parameters in different natures. It is a difficult task even for an expert to give a priority sequence for negotiations from the contents of the bids. This study proposes the application of fuzzy ranking method to compare and prioritize the TSP bids in order to produce a negotiation sequence. The results of this study allow investigations on the behaviors of the stakeholders in bid preparation and negotiation, as well as evaluation of service quality in the open railway market.
- Published
- 2009
24. PRIMARY 23-GAUGE TRANSCONJUNCTIVAL SUTURELESS VITRECTOMY FOR RHEGMATOGENOUS RETINAL DETACHMENT
- Author
-
Timothy Yuk-Yau Lai, Robert F. Lam, Can Yin-Fun Yuen, Gary Ka-Yau Lee, Dennis S.C. Lam, Benson T.O. Cheung, and Chi Wai Tsang
- Subjects
Adult ,Male ,Pars plana ,Sutureless vitrectomy ,medicine.medical_specialty ,Visual acuity ,genetic structures ,medicine.medical_treatment ,Treatment outcome ,Sensation ,Visual Acuity ,Ocular Hypotension ,Vitrectomy ,Retinal detachment surgery ,Ophthalmology ,medicine ,Humans ,Postoperative Period ,Prospective Studies ,Aged ,Pain, Postoperative ,business.industry ,Retinal Detachment ,Follow up studies ,Retinal detachment ,Choroid Diseases ,General Medicine ,Middle Aged ,Retinal Perforations ,medicine.disease ,eye diseases ,Treatment Outcome ,medicine.anatomical_structure ,Eye Foreign Bodies ,Female ,sense organs ,medicine.symptom ,business ,Conjunctiva ,Follow-Up Studies - Abstract
To describe the results of primary 23-gauge transconjunctival sutureless vitrectomy for rhegmatogenous retinal detachment (RRD).In a prospective case series, 24 eyes of 24 consecutive patients with RRD underwent primary 23-gauge transconjunctival pars plana vitrectomy with intraocular gas tamponade. Postoperative follow-up ranged from 6 months to 16 months.Fifteen eyes (62.5%) had multiple breaks. Seven eyes (29.2%) had inferior breaks. Other complications included giant tear in one eye, peripheral choroidal detachment in one eye, and concomitant macular holes in two eyes. The primary anatomical success rate was 91.7%. The mean postoperative visual acuity at postoperative month 3 improved from 20/41 to 20/25 (P = 0.111) and from 20/735 to 20/56 (P0.0001) in macula-on and macula-off cases, respectively. One patient (4.2%) had hypotony on postoperative day 1. No patients developed choroidal detachments. No sutures were used in any of the sclerotomy sites. Of the patients, 87.5% reported no or mild foreign body sensation, whereas 79.1% reported no or mild pain on the first postoperative day.Twenty-three-gauge transconjunctival sutureless vitrectomy appears to be a feasible option in treating RRD in selected cases, with the potential benefit of reducing postoperative ocular irritation.
- Published
- 2008
25. Surgically induced astigmatism in phacoemulsification, pars plana vitrectomy, and combined phacoemulsification and vitrectomy: a comparative study
- Author
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C. Y. F. Yuen, R. F. Lam, B. T. O. Cheung, Chi Wai Tsang, N. B. Baig, and Dennis S.C. Lam
- Subjects
Adult ,Male ,Pars plana ,medicine.medical_specialty ,Refractive error ,genetic structures ,medicine.medical_treatment ,Vitrectomy ,Astigmatism ,Young Adult ,Ophthalmology ,medicine ,Humans ,Prospective Studies ,Aged ,Aged, 80 and over ,Phacoemulsification ,medicine.diagnostic_test ,business.industry ,Corneal Topography ,Middle Aged ,medicine.disease ,Corneal topography ,eye diseases ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,Female ,Surgically induced astigmatism ,sense organs ,business - Abstract
To study the surgically induced astigmatism (SIA) in combined phacoemulsification and vitrectomy, and compare with that when either procedure is performed alone.This is a prospective comparative interventional trial comprising of 60 eyes of 60 consecutive patients with cataract and/or vitreo-retinal pathology. They were divided equally into three groups based on the type of procedure: Group A, phacoemulsification alone group, using a 3.0-3.2 mm wide unsutured sclero-corneal tunnel incision at 1.0 mm post-limbus at 10 o'clock; Group B, par plana vitrectomy alone group, using three sclerotomies at 3.5 mm post-limbus at 2, 8, and 10 o'clock (right eye) or at 2, 4, and 10 o'clock (left eye) positions; and Group C, combined phacoemulsification and pars plana vitrectomy group. Main outcome measures were the amplitude (K-induced) and the axis of SIA calculated by rectangular coordinate method using the Holladay-Cravy-Koch formula.The mean K-induced amplitudes were 0.19+/-0.14 D, 0.17+/-0.11 D, and 0.23+/-0.19 D for groups A, B, and C, respectively. The range of K-induced amplitudes for the entire cohort was 0.00-0.77 D. No overall statistically significant differences in the pre- and postoperative topographic astigmatism amplitudes and the K-induced between groups A, B, and C were found (all P0.05). Minor shifts, of doubtful clinical significance, in the axes of SIA were present.Combined phacoemulsification and pars plana vitrectomy does not induce significant astigmatic change per se, and its amount is similar to that when either procedure is performed alone.
- Published
- 2008
26. Optimal Track Access Rights Allocation for Agent Negotiation in an Open Railway Market
- Author
-
Chi Wai Tsang and Tin Kin Ho
- Subjects
Engineering ,business.industry ,Transaction processing ,Mechanical Engineering ,Multi-agent system ,Rational agent ,Service provider ,Track (rail transport) ,Computer security ,computer.software_genre ,ComputingMethodologies_ARTIFICIALINTELLIGENCE ,Computer Science Applications ,law.invention ,Consistency (database systems) ,Software agent ,law ,Automotive Engineering ,Internet Protocol ,business ,computer ,Computer network - Abstract
In open railway access markets, a train service provider (TSP) negotiates with an infrastructure provider (IP) for track access rights. This negotiation has been modeled by a multiagent system in which the IP and the TSP are represented by separate software agents. One of the tasks of the IP agent is to generate feasible (and preferably optimal) track access rights, subject to the constraints submitted by the TSP agent. This paper formulates an IP-TSP transaction and proposes a branch-and-bound algorithm for the IP agent to identify the optimal track access rights. Empirical simulation results show that the model is able to emulate rational agent behaviors. The simulation results also show good consistency between the timetables that were attained from the proposed methods and those that were derived by the scheduling principles adopted in practice.
- Published
- 2008
27. Differential Aqueous and Vitreous Concentrations of Moxifloxacin and Ofloxacin After Topical Administration One Hour before Vitrectomy
- Author
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Kwok Ping Chan, Kwong Wai Choy, Chi Pui Pang, Chi Wai Tsang, Wico W. Lai, Kai On Chu, and Chi Chiu Wang
- Subjects
Adult ,Male ,Ofloxacin ,medicine.medical_treatment ,Moxifloxacin ,Biological Availability ,Vitrectomy ,Microbial Sensitivity Tests ,Aqueous Humor ,Minimum inhibitory concentration ,Endophthalmitis ,Anti-Infective Agents ,Double-Blind Method ,Retinal Diseases ,medicine ,Humans ,heterocyclic compounds ,Prospective Studies ,Chromatography, High Pressure Liquid ,Aged ,Antibacterial agent ,Aza Compounds ,Aqueous solution ,business.industry ,Follow up studies ,Middle Aged ,biochemical phenomena, metabolism, and nutrition ,bacterial infections and mycoses ,medicine.disease ,Vitreous Body ,Ophthalmology ,Anesthesia ,Quinolines ,Female ,business ,Fluoroquinolones ,Follow-Up Studies ,medicine.drug - Abstract
Purpose To investigate the penetration of ofloxacin and moxifloxacin into the aqueous and vitreous after topical administration one hour before vitrectomy surgery. Design Prospective, randomized, double-blind case series study. Methods Twenty-seven patients undergoing vitrectomy were randomized to receive either topical ofloxacin 0.3% or moxifloxacin 0.5% every 10 minutes for one hour before surgery. Aqueous and vitreous samples were obtained and analyzed using high-performance liquidation chromatography. Results The moxifloxacin aqueous (1.576 ± 0.745 μg/ml) and vitreous (0.225 ± 0.013 μg/ml) levels were significantly higher than the ofloxacin aqueous (0.816 ± 0.504 μg/ml) (P = .0009) and vitreous (0.225 ± 0.013 μg/ml) [P = .0054] levels, respectively. The mean moxifloxacin aqueous and vitreous levels exceeded the minimum inhibitory concentration for 90% of isolates (MIC90) for a wide variety of bacteria implicated in endophthalmitis. In contrast, the aqueous level of ofloxacin exceeded the MIC90 of only a few organisms. Conclusions Moxifloxacin applied every 10 minutes during the hour before vitrectomy penetrated the eye significantly better than ofloxacin.
- Published
- 2007
28. Conflict Resolution through Negotiation in a Railway Open Access Market: a Multi-agent System Approach
- Author
-
Chi Wai Tsang and Tin Kin Ho
- Subjects
Engineering ,Service (systems architecture) ,business.industry ,Multi-agent system ,media_common.quotation_subject ,Geography, Planning and Development ,Transportation ,Service provider ,Computer security ,computer.software_genre ,Scheduling (computing) ,Supply and demand ,Negotiation ,Risk analysis (engineering) ,Open market operation ,Conflict resolution ,business ,computer ,media_common - Abstract
Open access reforms to railway regulations allow multiple train operators to provide rail services on a common infrastructure. As railway operations are now independently managed by different stakeholders, conflicts in operations may arise, and there have been attempts to derive an effective access charge regime so that these conflicts may be resolved. One approach is by direct negotiation between the infrastructure manager and the train service providers. Despite the substantial literature on the topic, few consider the benefits of employing computer simulation as an evaluation tool for railway operational activities such as access pricing. This article proposes a multi-agent system (MAS) framework for the railway open market and demonstrates its feasibility by modelling the negotiation between an infrastructure provider and a train service operator. Empirical results show that the model is capable of resolving operational conflicts according to market demand.
- Published
- 2006
29. Amino acid changes in functional domains of latent membrane protein 1 of Epstein–Barr virus in nasopharyngeal carcinoma of southern China and Taiwan: prevalence of an HLA A2-restricted ‘epitope-loss variant’
- Author
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Chi-Wai Tsang, Yi-Xi Liu, Jaw-Ming Cherng, Steven P. Lee, Hsiung-Ju Lin, and Jung-Chung Lin
- Subjects
China ,Herpesvirus 4, Human ,Restriction Mapping ,Taiwan ,Human leukocyte antigen ,Biology ,medicine.disease_cause ,Polymerase Chain Reaction ,Herpesviridae ,Virus ,Epitope ,Major Histocompatibility Complex ,Viral Matrix Proteins ,Epitopes ,Virology ,HLA-A2 Antigen ,otorhinolaryngologic diseases ,medicine ,Humans ,Amino Acid Sequence ,Genotyping ,DNA Primers ,Mutation ,Base Sequence ,NF-kappa B ,Genetic Variation ,Nasopharyngeal Neoplasms ,medicine.disease ,Epstein–Barr virus ,Peptide Fragments ,stomatognathic diseases ,Amino Acid Substitution ,Nasopharyngeal carcinoma - Abstract
Full-length sequences of the Epstein–Barr virus (EBV) gene for latent membrane protein (LMP)-1 from 22 nasopharyngeal carcinoma (NPC) biopsy specimens and 18 non-neoplastic counterparts (NPI) were determined. Relative to the B95-8 strain, the amino acid sequences of the toxic-signal and transformation domains were changed variably in NPC and NPI specimens; in contrast, no change was observed in the NF-κB (nuclear factor κB) activation domain. HLA typing revealed that 47 % of NPC and 31 % of NPI specimens were HLA A2-positive. A major A2-restricted epitope within LMP-1 (residues 125–133) was analysed. At residue 126, a change of L→F was detected in 91 % (20/22) of NPC and 67 % (12/18) of NPI specimens. In addition, a deletion at residue 126 was detected in one NPC sample from Taiwan. At residue 129, a change of M→I was observed in all samples, regardless of whether they were NPC or NPI. The changes in this peptide between NPC and NPI specimens, including mutation and deletion, are statistically significant (PXhoI site, the presence of a 30 bp deletion and the presence of a mutated, A2-restricted, T cell target epitope sequence. These results suggest that an EBV strain carrying an HLA A2-restricted ‘epitope-loss variant’ of LMP-1 is prevalent in NPC in southern China and Taiwan.
- Published
- 2004
30. Emodin ameliorates glucose-induced matrix synthesis in human peritoneal mesothelial cells
- Author
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Lei Shi Li, Susan Yung, Ryan Chi-Wai Tsang, Jack Kok-Hung Leung, Zhi-Hong Liu, and Tak Mao Chan
- Subjects
human peritoneal mesothelial cells ,medicine.medical_specialty ,Emodin ,Protein Kinase C-alpha ,extracellular matrix ,Biopsy ,Cell ,Biology ,Pharmacology ,Collagen Type I ,Epithelium ,Transforming Growth Factor beta1 ,chemistry.chemical_compound ,Transforming Growth Factor beta ,TGF-β1 ,Internal medicine ,medicine ,Humans ,Secretion ,Viability assay ,PKC ,Enzyme Inhibitors ,Phosphorylation ,Cyclic AMP Response Element-Binding Protein ,Cells, Cultured ,Protein Kinase C ,Protein kinase C ,Extracellular Matrix Proteins ,Cell growth ,Epithelial Cells ,Protein-Tyrosine Kinases ,Fibronectins ,Mesothelium ,Fibronectin ,Glucose ,Endocrinology ,medicine.anatomical_structure ,chemistry ,Nephrology ,Carcinogens ,biology.protein ,Tetradecanoylphorbol Acetate ,Peritoneum ,Cell Division - Abstract
Emodin ameliorates glucose-induced matrix synthesis in human peritoneal mesothelial cells. Prolonged exposure of human peritoneal mesothelial cells (HPMC) to high glucose concentrations in peritoneal dialysate is the principal factor leading to matrix accumulation and thickening of the peritoneal membrane, accompanied by progressive deterioration of transport functions. These changes are mediated in part through protein kinase C (PKC) activation and the induction of transforming growth factor-beta 1 (TGF-beta 1). Emodin (3-methyl-1,6,8 trihydroxyanthraquinone) has previously been demonstrated to reduce cell proliferation and fibronectin synthesis in cultured mesangial cells. How emodin modulates glucose-induced abnormalities in HPMC has not been elucidated and thus constitutes the theme of this study.We investigated the effects of emodin on the expression of PKC alpha, TGF-beta 1, fibronectin, and collagen type I in HPMC, and its effects on HPMC proliferation under physiologic (5 mmol) or high (30 mmol) glucose concentrations.Exposure of HPMC cultured with 5 mmol or 30 mmol D-glucose to emodin (20 microg/mL) resulted in an initial lag of proliferation by 2.3 to 2.7 days, but did not affect cell viability or morphology at confluence. D-glucose (30 mmol) induced TGF-beta 1 secretion in a time-dependent manner (3.72 +/- 0.29 and 4.30 +/- 0.50 pg/microg cellular protein at 24 hours and 48 hours respectively, compared to 2.13 +/- 0.23 and 2.65 +/- 0.32 pg/microg cellular protein at 24 hours and 48 hours, respectively for 5 mmol glucose; P0.001 at both time points). Such induction was ameliorated by emodin (20 microg/mL) (TGF-beta 1 concentration 2.25 +/- 0.15 and 2.96 +/- 0.33 pg/microg cellular protein at 24 hours and 48 hours, respectively, in the presence of emodin and 30 mmol D-glucose; P0.001 compared to 30 mmol D-glucose alone at both time points). Induction of TGF-beta 1 synthesis by 30 mmol D-glucose was associated with induction of PKC alpha, phosphorylation of cAMP-responsive element binding protein (CREB) and activating transcription factor-1 (ATF-1), and increased fibronectin and type I collagen translation. Emodin abrogated all these effects of concentrated glucose. Immunohistochemical staining showed that 30 mmol D-glucose induced cytoplasmic, perinuclear, and extracellular fibronectin and type I collagen expression by HPMC. Emodin reduced 30 mmol D-glucose-induced cytoplasmic and extracellular matrix synthesis to near basal levels.Our findings demonstrate that emodin ameliorates the undesirable effects of concentrated glucose on HPMC via suppression of PKC activation and CREB phosphorylation, and suggest that emodin may have a therapeutic potential in the prevention or treatment of glucose-induced structural and functional abnormalities in the peritoneal membrane.
- Published
- 2003
31. Different effects of amino acid-based and glucose-based dialysate from peritoneal dialysis patients on mesothelial cell ultrastructure and function
- Author
-
Jack Kok-Hung Leung, Susan Yung, Kar-Neng Lai, Ryan Chi-Wai Tsang, Tak Mao Chan, and Yuling Sun
- Subjects
Adult ,Male ,Cell Survival ,Cell ,Biology ,Andrology ,chemistry.chemical_compound ,Cell-matrix adhesion ,Dialysis Solutions ,Lactate dehydrogenase ,medicine ,Humans ,Doubling time ,MTT assay ,Amino Acids ,Cells, Cultured ,Transplantation ,Interleukin-6 ,Cell growth ,Peritoneal fluid ,Middle Aged ,body regions ,Glucose ,medicine.anatomical_structure ,chemistry ,Biochemistry ,Nephrology ,Ultrastructure ,Kidney Failure, Chronic ,Female ,Peritoneum ,Peritoneal Dialysis - Abstract
Background. Peritoneal dialysis fluid (PDF) containing amino acids has been introduced recently aiming to improve the nutritional status of PD patients. Dextrose-based PDFs have been implicated in progressive functional and structural deterioration of the peritoneal membrane. Limited data are currently available regarding the effect of amino acid-based PDF on the function and ultrastructure of human peritoneal mesothelial cells (HPMCs), which play a critical role in peritoneal membrane pathophysiology. Methods. We investigated the effects of two commercially available PDFs, which utilized dextrose (1.5% Dianeal) or amino acids (1.1% Nutrineal) as the osmotic agent, obtained from patients after a 4 h dwell, on HPMC proliferation (MTT assay and cell counting) and viability [lactate dehydrogenase (LDH)release], interleukin-6 (IL-6) secretion (commercial enzyme-linked immunosorbent assay) and ultrastructure (scanning and transmission electron microscopy). Results. Exposure of HPMCs to 1.5% Dianeal reduced cell proliferation, total cellular protein synthesis, IL-6 secretion and cell attachment, but prolonged the cell doubling time on recovery, and increased LDH release (p
- Published
- 2003
32. Results of high-density silicone oil as a tamponade agent in macular hole retinal detachment in patients with high myopia
- Author
-
Chi Wai Tsang, Wico W. Lai, Dennis S.C. Lam, Timothy Y Y Lai, Benson T.O. Cheung, and Can Y. F. Yuen
- Subjects
Male ,medicine.medical_specialty ,Visual acuity ,genetic structures ,Silicone Oils - therapeutic use ,medicine.medical_treatment ,Scientific Report ,Visual Acuity ,Retinal perforation ,Vitrectomy ,Myopia, Degenerative - complications ,Retinal Detachment - etiology - therapy ,Cellular and Molecular Neuroscience ,Ophthalmology ,Pressure ,Humans ,Silicone Oils ,Medicine ,Prospective Studies ,Macular hole ,Aged ,Aged, 80 and over ,Retinal Perforations - complications - therapy ,business.industry ,Retinal Detachment ,Retinal detachment ,Epiretinal Membrane ,Middle Aged ,Retinal Perforations ,medicine.disease ,eye diseases ,Sensory Systems ,Editorial ,Myopia, Degenerative ,Female ,sense organs ,Tamponade ,medicine.symptom ,Epiretinal membrane ,business ,Retinal hole - Abstract
Background: To evaluate the use of high-density silicone oil (HDSO) as a tamponade agent for retinal detachment secondary to myopic macular hole. Methods: 12 eyes of 12 patients with macular hole retinal detachment underwent pars plana vitrectomy, internal limiting membrane peeling and HDSO tamponade. No posturing was required postoperatively and HDSO was removed 3-4 months later. Outcome measures included macular hole closure and retinal attachment rates, best-corrected visual acuity (BCVA), and intraoperative and postoperative complications. Results: The mean age of the patients was 67.8 years and the mean spherical equivalent refractive error was -13.4 diopters. After the removal of HDSO, 10 (83%) eyes had macular hole closure with retinal reattachment without any tamponade. One eye had retinal reattachment after re-operation and the other refused further surgery. At the last follow-up, the median BCVA improved from 20/800 to 20/600 (p = 0.046). A transient increase in intraocular pressure was observed in 5 (42%) eyes and one eye each developed mild oil emulsification and transient peripheral choroidal detachment. None of the eyes was found to have severe intraocular inflammation post-operatively. Conclusions: HDSO seemed to be an effective tamponade agent for myopic macular hole retinal detachment. Further prospective controlled studies seem warranted., published_or_final_version
- Published
- 2007
33. The impacts of formation of owners' corporation on the property management market of home ownership scheme courts
- Author
-
Chi-wai. Tsang
- Subjects
Scheme (programming language) ,Finance ,Market economy ,business.industry ,Property management ,business ,Corporation ,computer ,computer.programming_language - Published
- 2012
34. Applications of reinforcement learning in an open railway access market price negotiation
- Author
-
Tin Kin Ho, Shun King Wong, and Chi Wai Tsang
- Subjects
TheoryofComputation_MISCELLANEOUS ,Negotiation ,Optimization problem ,Operations research ,Computer science ,media_common.quotation_subject ,Market price ,Revenue ,Reinforcement learning ,Price discrimination ,media_common - Abstract
In an open railway access market price negotiation, it is feasible to achieve higher cost recovery by applying the principles of price discrimination. The price negotiation can be modeled as an optimization problem of revenue intake. In this paper, we present the pricing negotiation based on reinforcement learning model. A negotiated-price setting technique based on agent learning is introduced, and the feasible applications of the proposed method for open railway access market simulation are discussed.
- Published
- 2008
35. Schedule Coordination through Negotiation between Train Service Providers in an Open Railway Access Market
- Author
-
Tin Kin Ho and Chi Wai Tsang
- Subjects
Flexibility (engineering) ,Schedule ,Operations research ,Computer science ,media_common.quotation_subject ,Service provider ,Scheduling (computing) ,Negotiation ,Software agent ,Revenue ,Quality (business) ,Coordination game ,Simulation ,media_common - Abstract
A schedule coordination problem involving two train services provided by different operators is modeled as an optimization of revenue intake. The coordination is achieved through the adjustment of commencement times of the train services by negotiation. The problem is subject to constraints regarding to passenger demands and idle costs of rolling-stocks from both operators. This paper models the operators as software agents having the flexibility to incorporate one of the two (and potentially more) proposed negotiation strategies. Empirical results show that agents employing different combination of strategies have significant impact on the quality of solution and negotiation time.
- Published
- 2006
36. Increased mesangial cell hyaluronan expression in lupus nephritis is mediated by anti-DNA antibody-induced IL-1beta
- Author
-
Ryan Chi-Wai Tsang, Tak Mao Chan, Jkh Leung, and Susan Yung
- Subjects
Adult ,Male ,medicine.medical_specialty ,Renal glomerulus ,medicine.medical_treatment ,Lupus nephritis ,Inflammation ,hyaluronan ,Pathogenesis ,Internal medicine ,medicine ,Humans ,RNA, Messenger ,Glucuronosyltransferase ,Hyaluronic Acid ,human mesangial cells ,Cells, Cultured ,Mesangial cell ,business.industry ,Middle Aged ,medicine.disease ,Molecular biology ,Lupus Nephritis ,Glomerular Mesangium ,Cytokine ,Endocrinology ,IL-1β ,Mesangium ,Nephrology ,Antibodies, Antinuclear ,anti-DNA antibodies ,Tumor necrosis factor alpha ,Female ,medicine.symptom ,business ,Hyaluronan Synthases ,Interleukin-1 - Abstract
The mechanism by which anti-DNA antibodies contribute to the pathogenesis of lupus nephritis (LN) remains to be fully elucidated. Hyaluronan (HA) is an important extracellular matrix constituent that accumulates during tissue injury, and participates in lymphocyte recruitment to sites of inflammation. The role of HA in the pathogenesis of LN has not been defined. We investigated the expression of HA in renal biopsies and circulating HA levels in patients with diffuse proliferative LN, and the effect of human anti-DNA antibodies on HA synthesis in cultured human mesangial cells (HMC). HA expression was increased in the mesangium, and in the periglomerular and tubular distribution in LN kidney biopsies. LN patients showed increased levels of circulating HA, especially during active disease, which correlated with anti-DNA antibody titers (r=0.35, P=0.0234). Anti-DNA antibodies isolated during active LN but not remission increased de novo synthesis of (3)H-labeled HA, which was accompanied by induction of HA synthase (HAS) II transcription, and enhanced IL-1beta, IL-6, and tumor necrosis factor-alpha secretion in HMC (P0.001 for all). Only anti-DNA antibody induction of IL-1beta enhanced HA synthesis, which was abrogated by inhibitors of de novo mRNA or protein synthesis. Our findings demonstrate that HA expression is significantly increased within the mesangium in diffuse proliferative LN mediated through anti-DNA antibody-induced IL-1beta. Given that HA plays a pivotal role during inflammatory responses, influences cellular behavior and assists in the recruitment of lymphocytes to sites of injury, it is likely that HA contributes to the pathogenesis of LN.
- Published
- 2006
37. Prevalence and mechanism of appositional angle closure in acute primary angle closure after iridotomy
- Author
-
Felix C.H. Li, Chi Wai Tsang, Barry Y M Yeung, Chung Chai Chi, Dennis S.C. Lam, Philip W C Ng, Clement C Y Tham, Thomas Y. H. Chiu, and Jimmy S. M. Lai
- Subjects
Male ,medicine.medical_specialty ,Intraocular pressure ,Iridectomy ,genetic structures ,medicine.medical_treatment ,Ultrasound biomicroscopy ,Gonioscopy ,Microscopy, Acoustic ,Glaucoma ,Iris ,Ciliary body ,Postoperative Complications ,Trabecular Meshwork ,Ophthalmology ,medicine ,Prevalence ,Humans ,Prospective Studies ,Intraocular Pressure ,Aged ,medicine.diagnostic_test ,business.industry ,Ultrasound ,Ciliary Body ,medicine.disease ,Surgery ,Apposition ,medicine.anatomical_structure ,Acute Disease ,Female ,Laser Therapy ,business ,Glaucoma, Angle-Closure - Abstract
Purpose: A prospective observational case series to assess the prevalence of appositional angle closure in darkness among iridotomized Chinese eyes after acute primary angle closure (APAC) with the use of both clinical methods and ultrasound biomicroscopy. Methods: Sixteen Chinese patients who had history of APAC and subsequent successful treatment with laser peripheral iridotomy were examined. Fourteen additional control subjects were studied. Gonioscopy and ultrasound biomicroscopic examination were performed in the dark. Gonioscopic appearance of the angle was assessed, and quantitative measurements of the angle from the ultrasound biomicroscopic images were taken. Results: Of the APAC eyes 55.6% had appositionally closed angle clinically and in 38.9% only Schwalbe's line was visi-ble on gonioscopy. Ultrasound biomicroscopy confirmed structurally different anterior segments between eyes with APAC and the control eyes. In particular, the trabecular-ciliary-process distances were markedly different between the two groups. Conclusion: This study documented a high prevalence of appositional closure in iridotomized eyes after APAC in Chinese patients. The anteriorly positioned ciliary body, as documented in these cases by ultrasound biomicroscopy, is the likely mechanism of the angle crowding in this patient population.
- Published
- 2005
38. A prioritized fuzzy constraint satisfaction approach to model agent negotiation for railway scheduling
- Author
-
Tin Kin Ho and Chi Wai Tsang
- Subjects
Negotiation ,Fuzzy constraint satisfaction ,Operations research ,Computer science ,Software agent ,Distributed computing ,media_common.quotation_subject ,Fuzzy set ,Service provider ,Fuzzy logic ,Scheduling (computing) ,media_common - Abstract
With the recent regulatory reforms in a number of countries, railways resources are no longer managed by a single party but are distributed among different stakeholders. To facilitate the operation of train services, a train service provider (SP) has to negotiate with the infrastructure provider (IP) for a train schedule and the associated track access charge. This paper models the SP and IP as software agents and the negotiation as a prioritized fuzzy constraint satisfaction (PFCS) problem. Computer simulations have been conducted to demonstrate the effects on the train schedule when the SP has different optimization criteria. The results show that by assigning different priorities on the fuzzy constraints, agents can represent SPs with different operational objectives.
- Published
- 2005
39. Vitrectomy with and without scleral buckle for inferior retinal detachment
- Author
-
Chi Wai Tsang, Y Y Y Kwong, Dennis S.C. Lam, and Wico W. Lai
- Subjects
medicine.medical_specialty ,medicine.medical_treatment ,Cryotherapy ,Vitrectomy ,Scleral buckle ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Ophthalmology ,medicine ,Humans ,Vitrectomy - methods ,business.industry ,Significant difference ,Retinal detachment ,Retinal ,medicine.disease ,Sensory Systems ,Surgery ,Scleral Buckling ,chemistry ,Research Design ,Retinal Detachment - surgery ,Tears ,business ,Scleral buckling - Abstract
In the article presented by Wickham and associates,1 the authors compared vitrectomy and gas for treating inferior break retinal detachments with vitrectomy, gas and scleral buckle. The study showed no significant difference in the final outcome between the two groups. While vitrectomy and gas for inferior break retinal detachments appears promising, there are several issues that we would like to raise. Firstly, the surgery was performed by a registrar, fellow, or consultant. These surgeons may have varying degrees of experience and the inconsistency may affect the rate of successful surgical outcome. Secondly, additional tears were treated with cryotherapy …
- Published
- 2005
40. Fornix-based trabeculectomy using the 'anchoring' corneal suture technique
- Author
-
Doris W.F. Yick, Philip W C Ng, Barry Y M Yeung, Chi Wai Tsang, and Dennis S.C. Lam
- Subjects
Adult ,Male ,Intraocular pressure ,medicine.medical_specialty ,genetic structures ,medicine.medical_treatment ,Mitomycin ,Trabeculectomy ,Cornea ,Asian People ,Ophthalmology ,Medicine ,Humans ,Major complication ,Intraocular Pressure ,Retrospective Studies ,Wound Healing ,Antibiotics, Antineoplastic ,Glaucoma medication ,business.industry ,Mitomycin C ,Fornix ,Suture Techniques ,Glaucoma ,Middle Aged ,medicine.disease ,Combined Modality Therapy ,eye diseases ,Surgery ,Maculopathy ,Female ,sense organs ,Safety ,business ,Conjunctiva ,Conjunctival wound - Abstract
Aim: To assess the safety and efficacy of fornix-based trabeculectomy with the ‘anchoring’ corneal suture technique in Chinese patients. Methods: A retrospective non-comparative case series of 66 eyes of 63 Chinese patients who underwent fornix-based trabeculectomy combined with intraoperative mitomycin C (MMC) 0.4 mg/mL for 2−5 min were studied. Conjunctival wound closure of all eyes was with the anchoring corneal suture technique using a 9−0 nylon suture to prevent leakage at the corneolimbal interface. The success rate, with or without anti-glaucoma medication, the complication rate and the longevity of the drainage blebs were analyzed. Results: At a mean follow-up period of 447.36 ± 337.98 days, the mean intraocular pressure decreased from 26.83 ± 7.90 mmHg to 17.74 ± 8.74 mmHg (P
- Published
- 2003
41. Reply
- Author
-
Chi Wai Tsang
- Subjects
Ophthalmology ,General Medicine - Published
- 2009
42. A prospective randomised trial of different doses of intravitreal triamcinolone for diabetic macular oedema.
- Author
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Lam, Dennis S. C., Chan, Carmen K. M., Mohamed, Shaheeda, Lai, Timothy Y. Y., Li, Kenneth K. W., Li, Patrick S. H., Chi-Wai Tsang, Wai-Man Chan, and Shanmugam, Mahesh P.
- Subjects
TRIAMCINOLONE ,EDEMA ,RETINA ,DIABETES ,OPTICAL coherence tomography ,OPHTHALMOLOGY - Abstract
Objective: To compare the safety and efficacy of different doses of intravitreal triamcinolone (ivTA) in treating clinically significant diabetic macular oedema (CSMO). Methods: 63 eyes of 63 patients with CSMO and central foveal thickness (CFT) of ‰250 µm on optical coherence tomography were randomised to receive 4 mg (n = 23), 6 mg (n = 20) or 8 mg (n = 20) ivTA. Patients were followed up for 6 months, and changes in best-corrected visual acuity (BCVA), optical coherence tomography CFT, standardised change in macular thickness (SCMT), and side effects such as intraocular pressure and cataractogenesis were compared between the three groups. Results: After ivTA injection, improvements of BCVA and CFT occurred in all groups. The mean BCVA improvement at 6 months was significantly higher for the 8 mg group compared with the 4 mg group, with 9.9 and 3.1 improvement in letters on the Early Treatment of Diabetic Retinopathy Study chart, respectively (p=0.047). The mean SCMT at 6 months for the 4, 6 and 8 mg groups was 28.7%, 42.3% and 60.5%, respectively (p = 0.06). The proportion of eyes with SCMT ‰75% at 6 months was higher in the 8 mg group, but the difference failed to reach significance (p=0.06). Ocular hypertensive responses (>21 mm Hg) occurred in 39%, 30% and 55% of eyes in the 4, 6, and 8 mg groups, respectively (p=0.27). Conclusions: Higher doses of ivTA may prolong the duration of visual benefit in diabetic CSMO and seemed to result in more sustained reduction in macular oedema. Further studies are warranted to investigate the optimum dose of ivTA in treating diabetic CSMO. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
43. Prevalence and mechanism of appositional angle closure in acute primary angle closure after iridotomy.
- Author
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Yeung, Barry Y. M., Ng, Philip W. C., Chiu, Thomas Y. H., Chi Wai Tsang, Li, Felix C. H., Chung Chai Chi, Lai, Jimmy S. M., Tham, Clement C. Y., and Lam, Dennis S. C.
- Subjects
ANGLE-closure glaucoma ,EYE examination ,GONIOSCOPY ,SLIT lamp microscopy ,OPHTHALMOLOGY - Abstract
Purpose: A prospective observational case series to assess the prevalence of appositional angle closure in darkness among iridotomized Chinese eyes after acute primary angle closure (APAC) with the use of both clinical methods and ultrasound biomicroscopy. Methods: Sixteen Chinese patients who had history of APAC and subsequent successful treatment with laser peripheral iridotomy were examined. Fourteen additional control subjects were studied. Gonioscopy and ultrasound biomicroscopic examination were performed in the dark. Gonioscopic appearance of the angle was assessed, and quantitative measurements of the angle from the ultrasound biomicroscopic images were taken. Results: Of the APAC eyes 55.6% had appositionally closed angle clinically and in 38.9% only Schwalbe's line was visi-ble on gonioscopy. Ultrasound biomicroscopy confirmed structurally different anterior segments between eyes with APAC and the control eyes. In particular, the trabecular-ciliary-process distances were markedly different between the two groups. Conclusion: This study documented a high prevalence of appositional closure in iridotomized eyes after APAC in Chinese patients. The anteriorly positioned ciliary body, as documented in these cases by ultrasound biomicroscopy, is the likely mechanism of the angle crowding in this patient population. [ABSTRACT FROM AUTHOR]
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- 2005
- Full Text
- View/download PDF
44. Results of high-density silicone oil as a tamponade agent in macular hole retinal detachment in patients with high myopia.
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Cheung, Benson T. O., Lai, Timothy Y. Y., Yuen, Can Y. F., Lai, Wico W. K., Chi-Wai Tsang, and Lam, Dennis S. C.
- Subjects
RETINAL detachment ,RETINOIDS ,VISUAL acuity ,RETINAL diseases ,INTRAOCULAR pressure ,SURGICAL complications - Abstract
Background: To evaluate the use of high-density silicone oil (HDSO) as a tamponade agent for retinal detachment secondary to myopic macular hole. Methods: 12 eyes of 12 patients with macular hole retinal detachment underwent pars plana vitrectomy, internal limiting membrane peeling and HDSO tamponade. No posturing was required postoperatively and HDSO was removed 3–4 months later. Outcome measures included macular hole closure and retinal attachment rates, best-corrected visual acuity (BCVA), and intraoperative and postoperative complications. Results: The mean age of the patients was 67.8 years and the mean spherical equivalent refractive error was - 13.4 diopters. After the removal of HDSO, 10 (83%) eyes had macular hole closure with retinal reattachment without any tamponade. One eye had retinal reattachment after re-operation and the other refused further surgery. At the last follow-up, the median BCVA improved from 20/800 to 20/600 (p = 0.046). A transient increase in intraocular pressure was observed in 5 (42%) eyes and one eye each developed mild oil emulsification and transient peripheral choroidal detachment. None of the eyes was found to have severe intraocular inflammation post-operatively. Conclusions: HDSO seemed to be an effective tamponade agent for myopic macular hole retinal detachment. Further prospective controlled studies seem warranted. [ABSTRACT FROM AUTHOR]
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- 2007
- Full Text
- View/download PDF
45. A prioritized fuzzy constraint satisfaction approach to model agent negotiation for railway scheduling.
- Author
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Chi-Wai Tsang and Tin-Kin Ho
- Published
- 2004
- Full Text
- View/download PDF
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