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Aims: To compare the quality of vision in pseudophakic patients implanted with aspherical and spherical intraocular lenses (IOLs). Materials and Methods: Randomized prospective longitudinal intrapatient comparison between aspherical and spherical IOLs performed on 22 patients who underwent bilateral cataract surgery. Best corrected visual acuity, subjective contrast sensitivity, Strehl ratio and spherical aberrations (SA), and higher order wavefront aberrations for a 3.5 mm and a 6.0 mm pupil were measured after 3 months of cataract surgery. Results: SA (Z4,0) decreased significantly in eyes with aspherical IOL implant (P = 0.004). Modulation transfer function (MTF) and point spread function (PSF) resulted no significant difference between the two groups (P = 0.87; P = 0.32). Conclusion: Although the SA is significantly lower in eyes implanted with aspherical IOL, the quality of vision determined with MTF and PSF does not significantly differ for subjective and objective parameters that were analyzed.

A case of horseshoe-shaped macular tear after blunt trauma with the course of the tear and the relevant findings obtained by spectral-domain optical coherence tomography (SD-OCT) is described. A 21-year-old man who had suffered blunt trauma 5 days previously visited our clinic complaining of vision loss in his left eye. Ophthalmic examination and SD-OCT images revealed a horseshoe-shaped macular tear. A month later at the second visit, the macular tear was found to have spontaneously closed. There have been many cases reported previously of the spontaneous closure of traumatic macular holes. A horseshoe-shaped macular tear is an atypical clinical presentation. However, the mechanism of spontaneous closure is hypothetically as same as that for a macular hole. High-resolution images and three-dimensional maps taken with SD-OCT can provide more details on macular diseases and are more useful than time-domain OCT images.

A 68-year-old man presented with redness of left eye since six months. Examination revealed bilateral corneal furrow degeneration. Left eye lesion was suggestive of conjunctival squamous cell carcinoma, encroaching on to cornea. Anterior segment optical coherence tomography (AS-OCT) confirmed peripheral corneal thinning. Fluorescein angiography confirmed intrinsic vascularity of lesion. Patient was managed with "no touch" surgical excision, dry keratectomy without alcohol, cryotherapy, and primary closure. Pathologic examination of removed tissue confirmed clinical diagnosis. Management of this particular case required modification of standard treatment protocol. Unlike the alcohol-assisted technique of tumor dissection described, ethyl alcohol was not used for risk of corneal perforation due to underlying peripheral corneal thinning. Likewise, topical steroids were withheld in the post-operative period. Three weeks post-operatively, left eye was healing well. Hence, per-operative usage of absolute alcohol and post-operative use of topical steroids may be best avoided in such eyes.

Cardiobacterium hominis is a member of the HACEK (Haemophilus sp., Actinobacillus actinomycetemcomitans, C. hominis, Eikenella corrodens, and Kingella kingae) group commonly associated with endocarditits and is normally present in the respiratory tract. We describe the first case of acute dacryocystitis with lacrimal abscess caused by C. hominis along with a brief review of the literature. The patient responded to oral and topical ciprofloxacin after incision and drainage and awaits dacryocystorhinostomy.

We aimed to evaluate the implantation of a posterior chamber intraocular lens (IOL) in the anterior chamber (AC) with the haptics passing through two iridectomies to the posterior chamber. A total of 33 eyes of 33 patients with inadequate posterior capsular support due to either previous aphakia or posterior capsular rupture during cataract extraction were included in the study. A double iridectomy was performed on all patients using a vitrectomy probe on the midperiphery of the iris. IOLs were implanted in the AC, and the haptics were passed through the iridectomies to the posterior chamber. The mean follow-up time was 25.3 months. AC hemorrhage occurred in five patients during the iridectomy procedure. Corneal edema was detected in eight of 14 patients with primary IOL insertions. Haptic dislocation was detected in only one patient. This technique may be a good alternative to scleral-fixated IOL implantation in eyes with aphakia.

Orbital cellulitis is a serious, yet uncommon infection in neonates. It can result in significant sight and life threatening complications. Most commonly, it occurs secondarily as the result of a spread of infection from the sinuses. Orbital cellulitis, secondary to dental infection is rare. We hereby report a case of orbital cellulitis secondary to dental infection in a 15-day-old neonate without any systemic features.

Retiform hemangioendothelioma (RH) is a distinct entity in the spectrum of vascular tumors with a high local recurrence rate. It is considered a low-grade, well-differentiated cutaneous angiosarcoma with low metastatic potential. We report here for the first time a case of medial canthus recurrent RH. It may be helpful in our practice to include RH as a differential diagnosis of eyelid lesions. It is noteworthy that the progressive course and recurrence tendency of RH might be misdiagnosed as angiosarcoma or basal cell carcinoma (BCC), if not expected and carefully evaluated by the pathologist.

Hyperhomocysteinemia is a well-known modifiable risk factor for thromboembolism. Retinal vascular occlusion in patients having hyperhomocysteinemia is a known entity, particularly in young patients. However, multiple extra macular branch retinal vein occlusion (BRVO) is a rare condition, which can be a presentation of this disease. We present a patient who had multiple extra macular BRVO; on complete systemic workup, he was found to have raised homocysteine levels.

Optic nerve head drusen (ONHD) are incidental ophthalmologic finding in the optic nerve. Patients with ONHD are often asymptomatic, but sometimes present with transient visual obscuration′s (TVO), the reported incidence of which is 8.6%. Optic nerve head drusen are of two types: Superficial; visible and deep. The deep-buried drusen mimic papilledema. Because of the varied presentation deep-buried drusen pose a diagnostic challenge to the ophthalmologists. In young patients, they are mistaken for papilledema as it is clinically difficult to detect a buried drusen in the optic nerve head, but are seen on the surface with aging as the retinal nerve fiber layer thins out. They are observed as pale yellow lesions more often located towards the poles. Clinical examination aided with diagnostic tests like computed tomography (CT) orbits and ultrasound B scan can help establish the diagnosis. Herein, we report a rare case of optic nerve head drusen in a young lady, who presented with loss of vision and clinical evaluation and investigations suggested ONHD with anterior ischemic optic neuropathy.

X-linked juvenile retinoschisis is a rare hereditary retinal disease characterized by a tangential splitting of the neurosensory retina which may cause early-onset visual impairment. Existence of the retinal neurosensory layer splitting on cross-sectional images of optical coherance tomography (OCT) and the absence of leakage on fluorescein angiography (FA) help confirming the diagnosis. Such diagnostic tests are also helpful in determining the management of the disease. However, most of the retinoschisis cavities remain stable and rarely extend to the posterior pole, many authors suggest laser prophylaxis to avoid the potential risk of retinal detachment due to holes in the outer retinal layer. Herein, we report a case with bilateral foveal retinoschisis accompanying unilateral peripheral retinoschisis who was evaluated with detailed ophthalmologic examination. Visual acuity, fundoscopy, OCT, and FA remained stable in the second year of follow-up after prophylactic argon laser treatment.

Introduction: E-learning is the use of internet for the purpose of education. E-learning in medical education is at a nascent stage in our country. The present study was carried out with the purpose of introducing e-learning to third year medical students in the subject of Ophthalmology and taking feedback on their attitude towards the new methodology of teaching and evaluating. Materials and Methods: E-learning was introduced to the seventh semester students of MBBS in the subject of Ophthalmology. The topics were converted to web friendly format and used for teaching and evaluating. Feedback was taken from the students on completion of the term on their attitudes towards e-learning and their views on the scope of e-learning in medical education. Results: All the students agreed on the usefulness of e-learning in medical education. Eleven students (27.5%) found the medium of e-learning to be interesting, 15 (37.5%) considered it to be easy and accessible, 10 (25%) found it to be fast and easy, 4 (10%) considered it to be a medium which can give updated information. Twenty-three (57.5%) students considered that e-learning should be a medium of instruction in all the subjects, 15 (37.5%) students considered its usefulness in clinical subjects only. Twenty-eight students (70%) desired that e-learning should be used to provide important notes, questions, MCQs on all topics. Conclusions: E-learning is well accepted as a medium of instruction by medical students.

Sphenoid sinus mucocele comprises only 2% of all paranasal sinus mucoceles. In literature, there is a case report on sphenoidal mucocele causing bilateral optic neuropathy, with unilateral partial recovery and cranial nerve palsy, but we did not come across any literature with bilateral optic neuropathy and ophthalmoplegia together caused by spheno-ethmoidal mucocele. We present such a rare case of spheno-ethmoidal mucocele causing bilateral optic neuropathy and unilateral sixth nerve palsy who had postsurgery, unilateral good vision recovery, and complete resolution of sixth nerve palsy.

Perioperative visual loss (POVL), a rare but devastating complication, has been reported after spine, cardiac, and head-neck surgeries.The various causes include ischemic optic neuropathy, central or branch retinal artery occlusion, and cortical blindness. The contributory factors described are microvascular diseases and intraoperative hemodynamic compromise. However, the exact association of these factors with post-operative blindness has not yet been confirmed. A case of POVL with caesarian section surgery is being presented. The visual loss occurred due to a combined occlusion of central retinal artery and vein.The causes, presentation, and risk factors of POVL after non-ocular surgery are being discussed.

Purpose: To evaluate the relationship between interocular asymmetries of corneal hysteresis (CH) and visual field defects in Korean patients with glaucoma., Methods: A total of 444 eyes from 222 participants with glaucoma in at least one eye were enrolled. CH was measured using an ocular response analyzer (Reichert Technologies Inc). Eyes of each participant were classified into "better eye" and "worse eye" based on the mean deviation (MD) value of visual field test. The correlation between interocular differences in intraocular pressure, axial length, central corneal thickness, CH, and MD values was evaluated using Spearman correlation analysis. To exclude the possible effect of antiglaucoma medication on corneal properties, additional analyses were performed on eyes without any glaucoma treatment at the time of CH measurement (treatment-naive group)., Results: Median (interquartile range) MD value was -3.71 dB (-6.87 to -1.30 dB) in the better eye and -10.20 dB (-16.32 to -5.62 dB) in the worse eye. When the correlation between the asymmetry of the MD value and asymmetry of intraocular pressure, axial length, central corneal thickness, and CH were evaluated, only interocular differences in CH were significantly associated with interocular differences in MD values (rho = 0.214, p = 0.001). Among the 222 participants, 60 (27.0%) were treatment-naive group. In these eyes, interocular differences in CH were also significantly associated with interocular differences in the MD values (rho = 0.285, p = 0.029)., Conclusions: The interocular asymmetry of CH was significantly correlated with the interocular asymmetry of visual field defects in glaucoma.

Purpose: To investigate the association between corneal hysteresis (CH) and rates of optic nerve head whole image capillary density (wiCD) loss over time in open-angle glaucoma (OAG)., Design: Observational cohort., Participants: One hundred seventy-four eyes (122 OAG and 52 glaucoma suspect eyes) from 112 patients over more than 2 years and 4 visits or more., Methods: Baseline CH measurements were acquired with the Ocular Response Analyzer. Linear mixed-effect models were designed to investigate the effect of CH, average intraocular pressure (IOP) during follow-up, and baseline visual field (VF) mean deviation (MD) on the rates of wiCD loss and circumpapillary retinal nerve fiber layer (cpRNFL) thinning over time, while adjusting for confounders. Interaction between CH or baseline MD and average IOP during follow-up were included in final models to evaluate the effect of baseline MD or average IOP during follow-up on structural changes for different values of CH., Main Outcome Measure: Effect of CH, IOP, and baseline MD on the rates of wiCD loss and cpRNFL thinning over time., Results: The average follow-up time was 3.9 years. In the multivariable model, non-Black race, higher average IOP during follow-up, lower baseline CH, lower baseline VF MD, and higher numbers of IOP-lowering medications were associated with faster rates of wiCD loss over time. For CH values 6 mmHg and 12 mmHg, every 1-mmHg increase in average IOP during follow-up was associated with 0.23% per year faster and 0.07% per year slower rates of wiCD loss over time, respectively. While every 1-mmHg decrease in CH was associated with 1.89% per year faster rate of wiCD loss for MD of -12 dB, it was associated with 0.81% per year faster rate of wiCD loss for MD of -3 dB., Conclusion: Lower CH values were significantly associated with faster rates of wiCD loss over time. In eyes with lower CH, both higher average IOP during follow-up and more severe glaucoma damage at baseline were associated with faster rates of wiCD loss and cpRNFL thinning. These results support CH as a useful parameter for risk assessment of glaucoma progression., Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references., (Copyright © 2022 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Context: Subclinical keratoconus is contraindication to refractive surgery. The currently used methods of preoperative screening do not always allow differentiating between healthy eyes and those with subclinical keratoconus.Aim: To evaluate biomechanical parameters of the cornea, waveform score (WS), and intraocular pressure (IOP) as potentially useful adjuncts to the diagnostic algorithm for precise detection of the early keratoconus stages and selection of refractive surgery candidates.Settings and Design: Department of Ophthalmology and prospective cross-sectional study.Patients and Methods: Patients enrolled in the study were diagnosed with refractive disorders. We assessed parameters of corneal biomechanics such as corneal hysteresis (CH), corneal resistance factor (CRF), Goldman-correlated IOP (IOPg), corneal compensated IOP, WS, and keratoconus match index (KMI). They were classified into one of three groups based on the predefined KMI range: Group 1 (from 0.352 to 0.757) - 45 eyes, Group 2 (from -0.08 to 0.313) - 52 eyes, and Group 0 - control group (from 0.761 to 1.642) - 80 eyes.Results: In both study groups, IOPg, CRF, and CH were decreased when compared to control (P < 0.0001). In control group, there was positive correlation between CH and KMI (P < 0.05), with no correlations in any of the two study groups. CRF correlated positively with KMI in control (P < 0.0001) and in Group 2 (P < 0.05).Conclusions: CH and CRF, together with WS and IOPg, consist a clinically useful adjunct to detect subclinical keratoconus in patients referred for refractive surgery when based on KMI staging. [ABSTRACT FROM AUTHOR]

Aim: To assess the changes in corneal hysteresis (CH) and corneal resistance factor (CRF) 1‑year following transepithelial corneal collagen cross‑linking (CXL) treatment in eyes of children with keratoconus. Methods: This case series was conducted in 22 eyes of 22 children. Children aged < 18 years with progressive keratoconus were included. They were treated with transepithelial CXL. Corneal biomechanical and anterior chamber parameters such as CH, CRF, and peak 1 were noted using ocular response analyzer, Pentacam, intraocular lens master, and anterior segment optical coherence tomography before and 1, 3, 6, and 12 months after treatment. Results: Our series had 22 eyes of 22 children with a mean age 15.7 ± 2.1 years. The CH and CRF 1‑year after treatment declined (difference of mean 0.1 mmHg (95% confidence interval [CI] 0.04–0.24), P = 0.2] and (difference of mean 0.1 mmHg [95% CI 0.04–0.30], P = 0.3), respectively. Peak 1 and peak 2 increased (difference of mean 0.1 mmHg [95% CI 0.006–0.008], P = 0.2) and (difference of mean 0.1 mmHg [95% CI 0.007–0.006], P = 0.3), respectively. The uncorrected distance visual acuity improved from 0.95 ± 0.34 logMAR to 0.68 ± 0.45 logMAR (P < 0.05). No statistically significant changes during 12 months follow‑up were observed in axial length, corneal volume, anterior chamber volume, and anterior chamber depth (P > 0.05). Conclusion: Transepithelial CXL in keratoconus in pediatric age group seems to have good stability in corneal biomechanical parameters after 1‑year. Further studies with a larger sample and better study design are recommended to confirm our findings. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate corneal viscoelastic and intraocular pressure (IOP) changes measured by an ocular response analyzer (ORA) after phacoemulsification and intraocular lens (IOL) implantation. Materials and Methods: Sixty-three eyes scheduled for cataract surgery were included in the study. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated IOP (IOPg) were measured by ORA preoperatively and postoperative 1st week, 1st month and 3rd month. Central corneal thickness (CCT) was measured using Orbscan II. Results: The mean CH decreased significantly from 10.28±1.61 mmHg preoperatively to 9.57±1.70 mmHg at 1 week (p=0.004) however increased to 10.21±1.61 mmHg at 3 month (p=0.9). The mean CRF decreased significantly from 10.61±1.89 mmHg preoperatively to 9.61±1.92 mmHg at 1 week (p=0.004) however increased to 10.51±1.69 mmHg at 3 month (p=0.8). The mean preoperative IOPg was decreased significantly in all postoperative measurements, (1st week p=0.03, 1st month p=0.01, 3rd month p=0.009). The mean preoperative IOPcc did not change significantly by first week and 1st month postoperatively (p=0.8, p= 0.2), however decreased significantly at 3rd month control. (p=0.04) Conclusions: Even the CH, CRF values decreased significantly in early postoparative period after phacoemulsification surgery, there was no change according to preoperative values in 3 months follow up. Mean İOPg and IOPcc values decreased in the postoperative period. That was showing that corneal biomechanical properties are influenced by phacoemulsification and IOL implantation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the relationship between corneal hysteresis (CH) and corneal resistance factor (CRF) with age, central corneal thickness (CCT), corneal curvature (KM), corneal volume (CV), and refractive error in naïve eyes.Methods: 105 healthy subjects (58 male and 47 female) were included in this study. The ages ranged from 19 to 82 years (mean 43.1 ± 15.4 years) and refraction between -11 D and +6 D (mean -0.79 ± 2.95 D). CH and CRF obtained with the Ocular Response Analyzer (ORA) were correlated with age, refractive error, Goldmann Applanation Tonometry (GAT), and with CCT, KM, CV obtained with the Pentacam, and with Corneal-Compensated Intraocular Pressure (IOPcc) and Goldmann-correlated intraocular pressure measurement (IOPg) obtained with ORA. A multivariable mixed effect model was used to evaluate associations among these parameters.Results: CH ranged from 6.9 to 14.6 mmHg (mean 10.26 ± 1.49 mmHg); CRF ranged from 5.8 to 17 mmHg (mean 10.38 ± 1.64 mmHg). Multivariate analysis showed a statistically significant correlation between CH with CCT (p < 0.001), and KM (p < 0.001), and between CRF with CCT (p < 0.001) and GAT (p < 0.001).Conclusions: Our findings support the hypothesis that CH and CRF are related to the corneal shape and thickness, and show a decrease of CH with age. [ABSTRACT FROM AUTHOR]

Purpose: To study the corneal biomechanical and morphological changes after photorefractive keratectomy (PRK) and the correlation with morphological parameters.Methods: 119 eyes of 75 subjects with a refraction ranging between -0.50 D and -14.50 D (mean = -4.7 ± 2.3 D) were included in this study. The differences in corneal hysteresis (CH) and corneal resistance factor (CRF) one, three, and six months after PRK have been correlated with effective treatment, central corneal thickness (CCT), and corneal volume (CV) variations at any follow-up utilizing the Pearson Index. Differences between preoperative and postoperative values of the analyzed parameters have been checked with Student T test.Results: Both CH and CRF showed a significant (p < 0.01) decrease at one, three, and six months' follow-up.Conclusion: Our findings suggest that after myopic PRK there is a significant decrease of CH and CRF immediately after treatment that remains stable over the follow-up. [ABSTRACT FROM AUTHOR]

Purpose: Corneal hysteresis (CH) is lower in glaucomatous eyes. The aim of this study was to determine and compare the change in CH over time between normal, open angle glaucoma (POAG) and diabetic subjects. Methods: We retrospectively analysed records of patients undergoing assessment with the Ocular Response Analyzer (Reichert, Corp., New York, NY, USA). Right eyes with at least 7 measurements were included. Patients with ocular pathology other than POAG were excluded. Two-sample t-tests, chi-squared and logistic regression were used to analyse data. Results: A total of 1418 normal and 322 POAG patients were included. Patients with POAG were significantly older (70.73 ± 11.33 vs. 61.59 ± 16.56 years; p < 0.001), had a longer follow-up (4.14 ± 1.34 vs. 2.72 ± 1.49 years; p < 0.001) and had lower CH (9.58 ± 2.17 vs. 9.95 ± 2.19 mmHg p = 0.01), but there were no gender differences between groups (61.5 vs. 57.7% female; p = 0.21). We observed a significantly greater decrease in CH among patients with POAG (-0.11 ± 0.73 vs. 0.07 ± 2.31 mm Hg/year; p = 0.02). The relation between ΔCH/year and diagnosis persisted after adjusting for age and follow-up time (OR 0.90; 95% CI 0.82, 0.99; p = 0.03). We found CH to be higher in diabetics vs. non-diabetics (10.34 ± 2.04 vs. 9.88 ± 2.19; p = 0.02), but ΔCH/year was not different (0.07 ± 1.27 vs. 0.03 ± 2.10; p = 0.77). Conclusions: Patients with POAG in this study had a significantly greater rate of CH decline compared to normal. There was no significant difference in rate of CH change in diabetic and non-diabetic patients. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to determine intraocular pressure (IOP) and corneal biomechanical properties in myopic patients in Suez Canal area in Egypt. Materials and methods: A total of 350 eyes of myopic patients (n = 179, age = 29.4 ± 8.9 years) with a mean refractive errors of spherical equivalent (SE) ± SD of -5.00D+2.8 D were recruited in this study. All participants in this study underwent standardized ocular examinations. Metrics of corneal biomechanical properties, including corneal hysteresis (CH), corneal resistance factor (CRF), and central corneal thickness (CCT), were measured with the ocular response analyzer (ORA). The ORA also determined the values of IOP [Goldmann-correlated intraocular pressure (IOPg)] and corneal-compensated intraocular pressure (IOPcc). Results: The mean CH was 9.3 ± 1.4. The mean CRF was 9.7 ± 1.6. The mean CCT was 535.1 ± 37.7 µm. The mean IOPg was 16.3 ± 3.13 mmHg and the mean IOPcc was 17.8 ± 2.9 mmHg. The relationship between CH, CRF, and CCT and between CRF and CH was significant (P < 0.0001). There was a negative correlation between CH and IOPcc and a positive correlation between IOPcc and refractive errors. IOPcc measured using ORA is greater than IOPg by 11.2% (P < 0.0001). The cutoff point of IOPcc was 19.2 mmHg. CH and CRF decreased in aged participants. Conclusion: CH and CRF of myopic Egyptians measured using the ORA have a positive but moderate correlation with CCT; the higher the CCT the higher the hysteresis and CRF. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to assess changes in corneal biomechanical properties in myopic eyes after laser in-situ keratomileusis (LASIK) with ocular response analyzer. Materials and methods: Corneal biomechanics was recorded before and 1 month after LASIK was done in 76 eyes for correction of myopia. Central corneal thickness (CCT) was also measured prior and 1 month postoperatively. Preoperative biomechanical values were compared with postoperative values and both were correlated with age, sex, and CCT and tissue ablation depth. Results: In all, 76 eyes of 38 patients were involved in this study. Mean preoperative corneal hysteresis (CH) and corneal resistance factor (CRF) were 9.7 ± 1.7 and 10.1 ± 1.7 mmHg respectively. Mean preoperative Goldmann correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) were 16.2 ± 3.8 and 17.3 ± 3.9 mmHg, respectively. There was a statistically significant reduction of these parameters postoperatively (CH = 8.0 ± 1.6, CRF = 7.4 ± 1.8, IOPg = 11.7 ± 3.1, and IOPcc = 14.4 ± 2.6) mmHg. A moderate positive significant correlation between CCT and CH, CCT and CRF was found. Conclusion: Corneal biomechanics represented in CH and CRF showed statistically significant reduction following LASIK. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate possible changes in corneal hysteresis (CH) after topical treatment with a prostaglandin analogue in medication-naïve eyes. Methods: This was a prospective, observational cohort study. Sixty-eight eyes of 68 patients were prospectively included who were newly diagnosed with primary open-angle glaucoma or ocular hypertension in our institution. All patients were treatment-naïve. Patients were evaluated at baseline and after 6 months of treatment with latanoprost in the eye with the lower intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT). The ocular response analyzer was used to measure CH. Results: CH increased significantly (p = 0.0001) from 8.96 ± 2.3 mmHg to 9.79 ± 1.97 mmHg, and this increase was correlated significantly (p = 0.0001, r = 0.64, r2 = 0.41) with the basal CH. We identified a weak but significant (r2 = 0.06, p = 0.01) relationship between the basal CH and the drug-induced reduction of the GAT IOP. Nevertheless, the increase in the drug-induced CH was not correlated with the decrease in the GAT IOP. Conclusion: Treatment with latanoprost increases CH. The CH increase was not correlated with the drug-induced decrease in the GAT IOP, which suggested a direct effect of latanoprost on the viscoelastic corneal properties. [ABSTRACT FROM AUTHOR]

Background: The aim was to evaluate the effects of the Valsalva manoeuvre on Ocular Response Analyzer (ORA) measurements.Methods: A total of 152 eyes of 76 healthy individuals were included. The biomechanical properties of cornea, including corneal hysteresis (CH), corneal resistance factor (CRF) and intraocular pressure (IOP) parameters, namely, cornea compensated IOP (IOPcc) and Goldmann correlated IOP (IOPg) as measured with ORA were obtained before and during the Valsalva manoeuvre. Wilcoxon test for group analysis, Mann-Whitney test for intergroup analysis, Generalized Estimating Equation, and Spearman's test for correlation analysis were used.Results: The mean age of the 76 subjects (52 female) was 34.18 ± 10.20 years (range, 21 to 58 years). The mean IOPcc was 14.50 ± 0.30 mmHg before and 19.80 ± 0.60 mmHg during the Valsalva manoeuvre (p < 0.001). The mean IOPg before the Valsalva manoeuvre was 15.02 ± 0.33 mmHg and during was 20.18 ± 0.63 mmHg (p < 0.001). The mean corneal hysteresis was 11.40 ± 0.15 mmHg before Valsalva manoeuvre, and 10.60 ± 0.16 mmHg during Valsalva manoeuvre (p < 0.001). Pre-Valsalva manoeuvre mean corneal resistance factor was 11.97 ± 0.16 mmHg, whereas during the Valsalva manoeuvre, the mean corneal resistance factor was 12.06 ± 0.20 mmHg (p < 0.001). There was no correlation between age and either pre- or during-Valsalva manoeuvre measurements. The change in IOPcc and corneal hysteresis before and during Valsalva manoeuvre showed no intersexual difference; however, IOPg and corneal resistance factor change before and during Valsalva manoeuvre were significantly higher in male subjects. A negative correlation between pre-Valsalva manoeuvre corneal hysteresis and pre- and during-corneal resistance factor difference (r = -0.167) was detected.Conclusions: Valsalva manoeuvre causes a statistically significant increment in IOPcc, IOPg and corneal resistance factor and statistically significant decrement in corneal hysteresis. For this reason, to obtain reliable results, ORA measurements should be performed in suitable positions and with clothes that do not increase thoracic or abdominal pressure. [ABSTRACT FROM AUTHOR]

Background The aim was to study the relationships between the output parameters of the Ocular Response Analyzer ( ORA) and those calculated from the raw ORA data and to ascertain the subject-related variations of ORA parameter calculation procedures. Method Six subjects were recruited for a prospective study. Up to 32 measurements by ORA were performed in series on the dominant eye of each subject. A relationship was examined between Goldmann-correlated intraocular pressure values ( IOPg) obtained from the standard ORA output and IOPg′ calculated from raw ORA data with a custom-written procedure. The same analysis was carried out for the parameters of corneal hysteresis ( CH and CH′). Data and statistical analysis included Epanechnikov kernel smoothing, orthogonal linear regression, hypothesis testing and bootstrap techniques. Results The group average (mean ± standard deviation) IOPg and CH values were 11.6 ± 1.8 mmHg and 10.7 ± 1.7 mmHg, respectively. A strong correlation was found between IOPg and IOPg′ and also between CH and CH′ parameters. There was a significant ( Behrens- Fisher test, p < 0.001) difference between subjects for both IOPg and CH calculations, in terms of the regression slope parameter. Conclusions Subject-related variations of ORA parameter calculation were demonstrated. This could indicate that currently employed estimators of IOP parameters include unreported algorithmic procedures that may lead to biased results. [ABSTRACT FROM AUTHOR]

Aim This study aims to investigate the corneal biomechanical properties of steroid sensitive refractive surgery patients and to compare these with those patients that did not have steroid induced ocular hypertension after refractive surgery. Material and methods This retrospective study in a tertiary care center involved 48 eyes with steroid induced ocular hypertension (Group I) and 61 eyes of age and sex matched refractive patients who used topical steroids for the same duration as group I without developing ocular hypertension (group II). All patients had preoperative ophthalmological examination, pachymetry and postoperative corneal hysteresis (CH) and resistance factor (CRF) measurements by ocular response analyser. The preoperative CH and CRF measurements of the two groups were compared. Results The mean CH was statistically lower in group I (6.89 ± 1.62) as compared to group II (7.80 ± 1.30) ( p = 0.001). The CRF was higher in group I (7.68 ± 2.26) as compared to group II (7.66 ± 1.72) but the difference was not statistically significant ( p = 0.96). The preoperative spherical refractive error ( r = 0.43, p = 0.00) and postoperative corneal thickness ( r = 0.58, p = 0.001) were moderately correlated with CH. Conclusions A statistically significant decrease in CH in subjects with steroid induced ocular hypertension is found. Previous studies have revealed an association of low CH with risk of glaucomatous damage of optic nerve. This may imply risk of optic disc damage in this ocular hypertension group if not recognized and treated properly. However the results should be confirmed with larger sample sizes. [ABSTRACT FROM AUTHOR]

Background: To evaluate and compare corneal biomechanical indices and their specificity among keratoconus (KC), keratoconus suspect (KCS), and normal eyes (NL) before and after controlling potential confounders. Materials and Methods: A total of 160 eyes in three groups were included prospectively: NL, KC, and KCS groups based on clinical examination and topography. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the ocular response analyzer. CH and CRF were compared between the three groups by analysis of variances test. Results: The three groups consisted of 80 NL, 48 KC, and 32 KCS eyes. The mean CH measured was 10.4 ± 1.25, 7.83 ± 1.28 and 10.17 ± 1.80 mm Hg in NL, KC and KCS eyes, respectively. The mean CRF was 10.23 ± 1.75, 6.5 ± 1.63 and 9.98 ± 2.00 mm Hg in NL, KC and KCS eyes, respectively. Mean CH and CRF were significantly different between the NL and KC (P < 0.05); however after controlling for central corneal thickness and sex; there was no significant difference between NL and KCS (P > 0.05). Conclusion: CH and CRF can be helpful in differentiating KC from NL eyes; however, they are not valuable for detecting KCS that is the main concern for refractive surgery. Future studies focusing on more accurate tests for identifying KCS, using a consistent grading scale for defining KC and KCS are still warranted. [ABSTRACT FROM AUTHOR]

Purpose: To observe the roles of cornea and axial length (AL) in corneal hysteresis (CH) among emmetropes and high myopes. Materials and Methods: The CH, corneal resistance factor (CRF) and corneal-compensated intraocular pressure (IOPcc) of 40 young emmetropes (spherical equivalent +/−0.50 D) and 40 age-matched high myopes (−6D or more) were measured by the Ocular Response Analyzer. AL was measured using a partial coherence interferometer. The mean keratometry reading (meanK) and corneal volume (CV) in 4 zones were measured using the Pentacam. Full stromal thickness (FST) and epithelial and Bowman's thicknesses (Epi + BT) were evaluated using confocal microscopy. Valid confocal microscopic results from the more emmetropic eyes of 30 emmetropes and the more myopic eyes of 27 high myopes were studied. Results: High myopes exhibited significantly longer AL (27.34 ± 0.90 mm versus 23.71 ± 0.79 mm), lower CH (10.17 ± 1.38 mmHg versus 11.11 ± 1.25 mmHg), and higher IOPcc (16.50 ± 3.05 mmHg versus 13.91 ± 2.49 mmHg) compared with emmetropes. The 2 groups showed similar CRF, CVs, meanK, FST and Epi + BT. By combining the results of both groups, CH and CRF were significantly correlated with FST ( r2 = 0.368 and r2 = 0.408, respectively), CVs ( r2 = 0.251-0.391 and r2 = 0.201-0.346, respectively), but not with Epi + BT or meanK. Furthermore, AL and IOPcc were significantly correlated with CH ( r2 = 0.112 and r2 = 0.161, respectively) but not with CRF. The multivariate analysis indicated that FST (standardized coefficients, β = 0.591) and CV ( β = 0.575) had stronger association than IOPcc and AL for CH. Conclusions: High myopes exhibited lower CH than emmetropes. Although CH had stronger correlation with FST than AL, it might contain the biomechanical properties of components other than the cornea. [ABSTRACT FROM AUTHOR]