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Background: To report the clinical and microbiological features of Acanthamoeba keratitis (AK) related to contact lens use in a tertiary hospital in China., Methods: In this retrospective study, the medical results of 61 cases of AK related to contact lens use from January 2000 to December 2017 were reviewed. The data included patients' demographics, lens type, history, risk factors, disease stages, corneal scraping and culture reports, and treatments. Moreover, genotypic identification of some of the isolates was carried out with a PCR assay and sequence analysis of the 18S ribosomal DNA gene., Results: There were 64 eyes included in the study. A total of 32.8% of the patients wore soft contact lenses, and 67.2% of patients used overnight orthokeratology. In the cases (20 eyes) in the early stage, 65% (13 eyes) had positive results according to Giemsa-stained smears, and 0.9% sodium chloride (NaCl) wet mounts revealed trophozoites in 7 eyes (35%). Six eyes (30%) were diagnosed by confocal microscopy combined with clinical signs. In the orthokeratology patients, 87.8% (36/41) rinsed their lenses and/or cases with tap water; 55% of soft-lens wearers wore their lenses while showering. The genotype of 9 isolates was determined, and all the strains belonged to genotype T4. In the orthokeratology group, the number of patients who required therapeutic penetrating keratoplasty after 2005 was less than that before 2005 (chi-square test, χ 2  = 4.209, P = 0.04)., Conclusions: More than two-thirds of the cases were associated with orthokeratology. Examinations with Giemsa-stained smears, 0.9% NaCl wet mounts and confocal microscopy should be performed for patients who are highly suspected of having early-stage AK to help with early diagnosis. In the orthokeratology group, the rate of therapeutic keratoplasty after 2005 was less than that before 2005.

Purpose: To determine risk factors and clinical signs that may differentiate between bacterial, fungal, and acanthamoeba keratitis among patients presenting with presumed infectious keratitis., Design: Hospital-based cross-sectional study., Methods: We examined the medical records of 115 patients with laboratory-proven bacterial keratitis, 115 patients with laboratory-proven fungal keratitis, and 115 patients with laboratory-proven acanthamoeba keratitis seen at Aravind Eye Hospital, Madurai, India, from 2006-2011. Risk factors and clinical features of the 3 organisms were compared using multinomial logistic regression., Results: Of 95 patients with bacterial keratitis, 103 patients with fungal keratitis, and 93 patients with acanthamoeba keratitis who had medical records available for review, 287 (99%) did not wear contact lenses. Differentiating features were more common for acanthamoeba keratitis than for bacterial or fungal keratitis. Compared to patients with bacterial or fungal keratitis, patients with acanthamoeba keratitis were more likely to be younger and to have a longer duration of symptoms, and to have a ring infiltrate or disease confined to the epithelium., Conclusions: Risk factors and clinical examination findings can be useful for differentiating acanthamoeba keratitis from bacterial and fungal keratitis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

A 31-year-old woman developed a spontaneous flap interface keratitis in the left eye 6 years after a laser in situ keratomileusis (LASIK) enhancement. Cultures and polymerase chain reaction (PCR) were positive for Achromobacter xyloxidans resistant to first- and second-generation cephalosporin, aminoglycosides, and quinolones and also positive for Acanthamoeba T4. Treatment with topical fortified ceftazidime, topical chlorhexidine, and voriconazole and oral voriconazole did not stop the progression of the disease. Flap amputation revealed persistence of Acanthamoeba but not Achromobacter. Six weeks after flap amputation, the infiltrate had resolved, PCR was negative for Acanthamoeba, and the cornea had fully epithelialized. To our knowledge, this is the first report of post-LASIK infectious keratitis caused by mixed infection of Achromobacter xyloxidans and Acanthamoeba occurring years after the procedure without apparent ocular trauma. It is also the first report of the use of combined systemic and topical voriconazole as a therapy for Acanthamoeba keratitis after LASIK., (Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Aim: The aim of the study was to identify the epidemiological characteristics, predisposing factors, and the clinical and microbiological diagnosis of infectious corneal ulcers in a population based in southern England., Methods: A retrospective review was undertaken of the medical records of patients presenting with infectious corneal ulcers at the eye casualty department of Queen Alexandra Hospital, Portsmouth, UK, between January 1997 and December 2003., Results: A total of 1786 patients presented with infectious corneal ulcers, with a mean age of 45 years and female predominance (54.5%). Contact lens wear was the main predisposing factor in 554 patients (31%). Corneal scrapes from 1254 patients grew positive cultures in 800 patients. Gram-positive bacteria accounted for 696 (71.1%) of the total 979 bacterial isolates, while Gram-negative bacteria accounted for 283 (28.9%) with the predominance of Pseudomonas aeruginosa. Nine out of 11 patients with Acanthamoeba keratitis were contact lens wearers. The majority of patients 1728 (96.8%) sought medical help more than once and 34 patients (1.9%) had poor visual outcome. Follow-up was completed in 1633 patients (91.4%) with an average of 11.5 days., Conclusions: Wearing contact lenses remains the most important risk factor for infectious corneal ulcers. Reduction of the rate and severity of infectious keratitis requires continuous education of patients, and of professionals.

Purpose: To determine the predisposing factors, demographic characteristics, and etiology of ulcerative keratitis in a referral center in Bangkok, Thailand., Methods: The medical records of admitted patients with positive-culture ulcerative keratitis were retrospectively reviewed for demographic data, predisposing factors, and microbial culture results. Predisposing factors were compared between bacterial and fungal keratitis., Results: From January 2001 to December 2004, there were 127 positive-culture ulcerative keratitis cases. The most frequent microbiological diagnosis was bacterial keratitis (76 eyes, 60%), followed by fungal (48 eyes, 38%) and Acanthamoeba keratitis (3 eyes, 2%). The most common organisms isolated were Pseudomonas spp. for bacteria and Fusarium spp. for fungus. Compared with bacterial keratitis, fungal keratitis was more likely to be associated with ocular trauma (odds ratio = 11.20; 95% confidence interval, 3.62-34.66) but less likely to be associated with contact lens wear (odds ratio = 0.02; 95% confidence interval, 0.01-0.08)., Conclusions: In our study, Pseudomonas and Fusarium species are the most common causes of bacterial and fungal keratitis, respectively. Fungal keratitis was more likely than bacterial keratitis to be associated with ocular trauma, whereas fungal keratitis was less likely to be associated with contact lens wear.

Purpose: To report 28 cases of infectious keratitis related to orthokeratology lens overnight wear in China., Methods: From March 2000 to August 2001, 28 cases of infectious keratitis related to overnight orthokeratology lens wear were diagnosed in Beijing Institute of Ophthalmology. These were retrospectively reviewed with regard to the pathogens isolated, duration of wear, the time since onset of symptoms, and age. Cultures of corneal scrapes for bacteria, fungus and Acanthamoeba were performed in all of the 28 cases., Results: All cases were students, including 10 males and 18 females, average age was 16 years (range 10-21 years). The duration of orthokeratology overnight wearing was from 2 weeks to 2 years. Uncorrected visual acuity (UCVA) on initial examination in our institute was from 20/200 to light perception. Of 28 isolates, 24 were culture positive (including 11 bacteria, 11 Acanthamoeba and two fungi), and four were culture negative. In two of the four culture negative cases, Acanthamoeba cysts were detected in the corneal stroma with the confocal microscope. Acanthamoeba and Pseudomonas aeruginosa accounted for 75% (21 of 28) of the cases of infectious keratitis., Conclusion: Infectious keratitis is a severe complication associated with overnight orthokeratology lens wear. Ophthalmologists should pay more attention to this complication in practice.

Purpose: To report the microbial culture results, clinical course, and visual outcomes for infectious keratitis related to overnight orthokeratology., Methods: The records of patients with infectious keratitis related to overnight orthokeratology who presented to a tertiary referral center from April 2000 to March 2003 were retrospectively reviewed., Results: Twenty patients (21 eyes) were included; 1 patient had bilateral infections. The average age of the patients was 14 years. The average period between the time the patient started the overnight orthokeratology program and the onset of infectious keratitis was 23 months. Thirteen of the 21 eyes were culture positive. Organisms cultured were Pseudomonas aeruginosa (n = 9), coagulase-negative Staphylococcus species (n = 2), Serratia marcescens (n = 1), and Acathamoeba species (n = 1). All patients responded well to medical antimicrobial treatment. Final best spectacle-corrected visual acuity ranged from 20/20 to 20/100., Conclusions: Infectious keratitis is a potential complication of overnight orthokeratology that may cause significant visual impairment. Parents of children who consider overnight orthokeratology should evaluate the benefit of temporary myopia reduction and the risk of infection.

Purpose: To report 3 cases of infectious keratitis related to overnight orthokeratology use., Methods: Retrospective case observation., Results: All 3 patients were using overnight orthokeratology lenses when they presented with unilateral corneal ulcers. The organisms isolated were Acanthamoeba, Pseudomonas aeruginosa, and Serratia marcescens. The clinical presentation and treatment of each case is presented., Conclusions: Overnight orthokeratology use may be associated with infectious keratitis despite the use of more oxygen-permeable materials and improved lens design. Patient education with informed consent, appropriate lens care, and meticulous follow-up is important. Because this complication is potentially sight threatening, orthokeratology requires further analysis and evaluation to establish its safety. The cases here are the first few reported cases in North America.

Purpose: Despite growing evidence for clinical efficacy of orthokeratology (OK) for the temporary reduction of myopic refractive error, there has been an increasing number of reports of microbial keratitis (MK) in association with overnight wear of OK lenses. This article analyzes the first 50 cases of MK reported in overnight OK, in order to define the spectrum of the disease and to identify possible risk factors., Methods: All reported cases of presumed MK in overnight OK from 2001 onwards were included in the analysis. Demographic data of patients affected and lenses worn, and details of the disease process and possible risk factors were extracted from these reports., Results: Most cases of MK in OK were reported from East Asia (80%) and most affected patients were Asian (88%). The peak age range was from 9 to 15 years (61%). Although Pseudomonas aeruginosa was the predominant organism implicated in this series of cases (52%), an alarmingly high frequency of Acanthamoeba infection (30%) was found. Inappropriate lens care procedures, patient noncompliance with practitioner instructions, and persisting in lens wear despite discomfort emerged as potential risk factors., Conclusions: The high frequency of MK in overnight OK in young Asian patients is likely to reflect the demographics of the OK lens-wearing population. The high frequency of Acanthamoeba infection strongly suggests that tap water rinsing should be eliminated from the lens care regimen for overnight OK. This study does not reveal the absolute incidence or relative risk of MK in overnight OK, and it is therefore premature to ascribe increased risk to this lens-wearing modality compared with other contact lens modalities.

Orthokeratology is a method of changing refraction in myopic patients by using rigid contact lenses to reduce the curvature of the cornea. This treatment was in use in the two cases of corneal ulcer described in this paper and appears to have contributed to the development of their disease. As with extended wear contact lenses, patients undergoing orthokeratology treatment are frequently advised to wear the orthokeratology lenses overnight increasing the risk of corneal ulceration and infection. Patients should be adequately warned of the associated risks and advised that any envisaged benefits of the procedure are temporary.

Microbial keratitis has been studied in Hong Kong as a representative sub-tropical climate of south China. An 18-month investigation in 1997/98 of 223 cases of ulcerative keratitis (presumed microbial) was conducted in the 2 million population of Shatin and Kowloon at the Prince of Wales and Hong Kong Eye Hospitals respectively with comprehensive microbiology. A case-control study was pursued at the same time between 45 contact-lens wearers (CLW) developing microbial keratitis and 135 lens-wearing volunteers matched for age, sex, educational status and visual acuity. Home water supplies were sampled for Acanthamoeba. Previous ocular surface disease and trauma (preventable by wearing goggles for grinding) were common predisposing causes while cosmetic wear of contact lenses was responsible for 26% of cases overall. Pseudomonas aeruginosa was the commonest bacterium isolated, from both CLW and non-CLW, with infection being acquired within the community. These 28 pseudomonads remained fully sensitive to the third-generation cephalosporins, aminoglycosides and quinolone antibiotics, which is very encouraging. Fungi were isolated, predominantly Fusarium sp., but less commonly than expected. A fungal/bacterial ratio was obtained of 1/17, while in comparison, the expected ratio for a tropical climate ranges from 1/5 (Singapore) to 1/2 (South India). Acanthamoeba was the second commonest microbe isolated from keratitis of CLW. The domestic water environment of 8% of homes of both patients and controls wearing contact lenses was colonized with Acanthamoeba. Lack of hygiene, use of tap water for storing lenses, failure to air-dry lens-storage cases or use of one-step hydrogen peroxide disinfectant were identified as risk factors for keratitis in CLW. The study results commend use of multipurpose solutions by CLW in Hong Kong to achieve the lowest expected rates of infection.

Three female patients, aged from 17 to 44 years, developed Acanthamoeba keratitis associated with the use of soft contact lenses and cosmetic contact lens. Two of these patients were myopic and wore soft contact lenses for optical purpose, while the third patient used a cosmetic lens. In this paper we describe the related risk factors, the success of cultural procedures and the outcome of medical management. In 2 out of the 3 cases we obtained cultures positive for Acanthamoeba, from the contact lenses and the contact-lens case. The isolated strains belong to the group II according to Pussard and Pons and they were proven pathogen for experimentally infected mice. All infections were treated successfully; however in 2 out of the 3 patients the visual acuity was reduced to the light perception.

Purpose: To describe a case of Acanthamoeba infection of the cornea after radial and astigmatic keratotomy., Methods: A 29-year-old man developed ulcerative keratitis in the right eye 6 weeks after uncomplicated radial and astigmatic keratotomy., Results: Three sets of corneal cultures for bacteria and fungi were negative. Culture on non-nutrient agar grew Acanthamoeba organisms. Clinical improvement occurred after topical antiamebic therapy was instituted., Conclusions: Incisional keratotomy may predispose the cornea to delayed-onset infectious keratitis. Acanthamoeba should be considered as a possible cause of infection and should be cultured for in refractory cases.

Charts of 320 patients with corneal ulcers seen on the Cornea Service of Wills Eye Hospital from July 1, 1992, to June 30, 1995, were reviewed retrospectively. Of these cases, 96 (30%) were associated with contact lens use. Ulcers in contact lens users accounted for 36% of cases in the last 6 months of 1992 and all of 1993, 20% of cases in 1994, and 29% in the first 6 months of 1995. The contact lenses most commonly associated with ulcers were disposable extended-wear lenses. They were used in 33% of contact lens-associated ulcers in 1992, 27% in 1993, 39% in 1994, and 44% in 1995. Pseudomonas was the predominant organism prior to 1993 (1-4). From 1993 to 1995, however, the number of Pseudomonas ulcers steadily decreased. Two or three Acanthamoeba infections continue to be treated each year. There has been a significant decrease in the number of contact lens-related ulcers treated at our institution compared with previous years (p < 0.01) (3, 4).

Purpose/methods: Eight years after eight-incision radial keratotomy, a corneal ulcer developed around the inferotemporal incision in an otherwise healthy 39-year-old man. There was no history of corneal trauma or contact lens wear., Results/conclusions: Both Fusarium and Acanthamoeba organisms were eventually isolated from the ulcer. A therapeutic keratoplasty was performed. Inferotemporal incisions may be predisposed to epithelial breakdown and infection many years after radial keratotomy.

All hospitalized cases of contact lens induced keratitis with stromal involvement among cosmetic wearers in Sweden over a 3-year period were reviewed for risk factors in relation to lens type and wear schedule. Information on every case was obtained from ophthalmology departments. Lens type and wear schedule were identified. The number of lens wearers, subdivided by lens type and wear schedule, was obtained from a study by the Swedish Contact Lens Association. Annual incidence figures were then calculated as expressions of risk factors. There were 30.7 cases per year, on average, of hospitalized lens induced keratitis in Sweden. The annual incidence per 10,000 wearers was 0.51 for daily wear and 3.12 for extended wear of conventional soft lenses, 0.16 for daily wear and 4.17 for extended wear of disposable soft lenses, and 1.21 for daily wear of rigid gas permeable lenses. It may be concluded that daily wear of disposable lenses was associated with significantly (P < 0.05-0.01) less risk of hospitalized keratitis than daily wear of the other lens types. Extended wear of conventional and disposable soft lenses showed a significantly (P < 0.01-0.001) higher risk of hospitalized keratitis than daily wear. However, the two extended wear groups did not differ significantly (P > 0.2). Microbial keratitis was significantly (P < 0.001) more common than sterile (no growth of microbes) keratitis among conventional soft lens wearers, whereas the opposite was true (P < 0.05) among disposable lens wearers.

In seventeen patients who suffered of corneal ulcer, and were negative in bacteriological and mycological examinations, parasitological tests were performed between 1990-1992. Acanthamoeba keratitis was diagnosed in one patient with characteristic corneal changes of right eye following trauma. The patient was not a contact lens wearer. The amoeba found in direct smears of scraping from corneal ulcer and isolated and cloned in in vitro conditions (isolate-clone-No. 2961) belonged to Acanthamoeba polyphaga species. The trophozoites showed a low degree of invasiveness and high virulence when tested in BALB/c mice. The authors discussed the epidemiology of Acanthamoeba keratitis and pointed out to the necessity of accurate laboratory diagnosis and discerning interpretation of the results to prevent an Acanthamoeba-phobia among the potential patients and most of all among the medical staff.

Infectious keratitis is the most serious complication of contact lens use. Virtually all contact lens wearers are at risk. Initial therapy consists of frequent broad-spectrum fortified antibiotic drops after appropriate laboratory workup. Pseudomonas and Acanthamoeba species are the most important causes of contact lens-associated ulcers. Acanthamoeba keratitis produces significant ocular morbidity, and treatment is not always effective. Recent studies have provided new insights regarding the incidence, risk factors, and pathogenesis of contact lens-related infectious keratitis. Extended-wear soft contact lens wearers are at greatest risk. With our present understanding of the pathogenesis and risk factors of contact lens-related infectious keratitis, daily-wear schedules are strongly advised. Even under the best of lens care conditions, infectious keratitis may still occur. It is therefore imperative that patients be informed to remove their lenses and seek medical evaluation if any discomfort develops.

Disposable soft contact lenses have been marketed as a safer alternative to conventional soft lenses. We undertook a case-control study of patients attending the casualty unit of an eye hospital to quantify the relative risk of keratitis in disposable lens wear and to establish associated patterns of use. All eligible contact lens users were identified and asked to complete a questionnaire (n=242). Keratitis, microbial or sterile, was the most common complication in disposable lens users, occurring in 16 of 41 subjects. The relative risks for all lens types were estimated by comparison with rigid lenses (the referent). Both extended- and daily-wear disposable lenses were associated with higher risks of keratitis than other lens types including conventional extended-wear lenses. Poor hygiene, disinfectant system failure, and lens type may all account for these statistically significant trends.