Search

Topic: To evaluate the safety and efficacy of transepithelial corneal cross-linking in comparison with the established epithelium-off technique for corneal ectasia., Clinical Relevance: Considerable debate exists regarding whether transepithelial and epithelium-off cross-linking are comparable in their safety and efficacy., Methods: We searched 16 electronic databases, including Medline, Embase, Web of Science, and the grey literature, current to July 8, 2020, for randomized controlled trials comparing transepithelial and epithelium-off cross-linking for corneal ectasia. We excluded studies evaluating cross-linking for nonectatic indications, as well as non-randomized controlled trials. Our primary outcome was the change in maximal keratometry (K max ) at 12 months after cross-linking, and we considered additional topographic, visual, and safety outcomes. We summarized our analyses by calculating weighted mean differences (MDs) with associated 95% confidence intervals (CIs) for continuous outcomes and relative risks (RRs) with corresponding 95% CIs for dichotomous outcomes. We conducted trial sequential analysis to determine whether the required information size was met for each outcome. The quality of individual trials was evaluated using the Cochrane Collaboration's risk of bias assessment tool, and the evidence was assessed at an outcome level using the Grading of Recommendations Assessment, Development, and Evaluation methodology., Results: Twelve studies totaling 966 eyes were eligible. A significant difference was found between transepithelial and epithelium-off cross-linking groups in the change in K max at 12 months (MD, 0.75; 95% CI, 0.23-1.28; P = 0.004; primary outcome) and at longest follow-up (MD, 1.20; 95% CI, 0.62-1.77; P < 0.001; secondary outcome) after treatment. No significant difference was found between the 2 groups when examining uncorrected distance visual acuity (MD, 0.04; 95% CI, -0.06 to 0.14; P = 0.386) or corrected distance visual acuity (MD, 0.01; 95% CI, -0.06 to 0.09; P = 0.732). Transepithelial cross-linking was associated with significantly fewer complications than the epithelium-off approach (RR, 0.22; 95% CI, 0.06-0.79; P = 0.020), although it was associated with an increased rate of disease progression at 12 months after treatment (RR, 4.49; 95% CI, 1.24-16.25; P = 0.022). The required information size was met for our primary outcome and trial sequential analysis supported the conventional meta-analysis. The quality of evidence was rated as moderate using the Grading of Recommendations Assessment, Development, and Evaluation methodology., Discussion: The efficacy of transepithelial cross-linking remains inferior to the epithelium-off approach, although it is significantly safer., (Copyright © 2020 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objective: The Goldmann applanation tonometer presents the problem of being one of the most widely used pieces of equipment in the ophthalmic clinic and a known risk factor for the transmission of epidemic keratoconjunctivitis (EKC). The purpose of this review is to assess the effectiveness of 3 methods of disinfection: alcohol swabs, immersion in peroxide, and the use of disposable prisms. An economic evaluation is undertaken to assess the cost-effectiveness of the 3 alternatives. In doing so, we contribute an evidence-based overview of the issue at an opportune time, because several jurisdictions are developing protocols regarding tonometer tip disinfection., Design: Systematic review and cost-effectiveness analysis., Methods: A comprehensive literature review was undertaken with a librarian, comprising searches of 6 electronic databases and hand searches of the grey literature. A 3-level screening process was undertaken by 2 reviewers according to prespecified inclusion and exclusion criteria. Values from included papers were used to inform a cost-effectiveness analysis undertaken using a decision tree model implemented in TreeAge. The analysis was undertaken from the hospital perspective and included all equipment and labour costs., Results: Synthesis of in vitro data indicates that all 3 methods are plausible methods of disinfection with a 64% reduction in log growth of EKC when peroxide is used compared with alcohol swabs. The incremental cost-effective ratios from the cost-effectiveness analysis were $12,000/case averted using peroxide and $61,000/case averted with Tonosafe as compared with alcohol., Conclusions: Assuming clinical infection rates match in vitro disinfection data, the cost of bleach is high and the cost of Tonosafe is unacceptably high to reduce 1 potential case of adenoviral keratoconjunctivitis., (Copyright © 2014. Published by Elsevier Inc.)

Objective: The objective of this project was to perform a cost-effectiveness analysis (CEA) of immediately sequential bilateral cataract surgery (ISBCS) versus delayed sequential bilateral cataract surgery (DSBCS) to determine whether ISBCS represents an appropriate, cost-effective way to rapidly rehabilitate a patient's visual impairment., Design: A systematic review followed by a primary economic analysis with computer-based econometric modeling., Participants: Not applicable., Methods: We constructed a decision analytic model from the perspective of the public third-party payer (i.e., the Ministry of Health) to conduct a CEA of both surgeries, ISBCS and DSBCS. Cost data consisted of the costs of the surgery, intravitreal injections, medications, and drops, all of which were obtained from a comprehensive literature search and from records at St. Joseph's Hospital, London, Ont. The effectiveness was measured by the utility values associated with visual acuity in the better seeing eye., Results: ISBCS resulted in an incremental effectiveness of 0.08 utility at an incremental cost of $1607. Discounting the quality-adjusted life-years (QALYs) gained by an annual interest rate of 3% resulted in 0.932 QALYs gained. The cost-effectiveness of ISBCS was calculated to be $1431 per QALY gained. A 1-way sensitivity analysis was performed by varying costs, utility values, probabilities, and discounting rates. This analysis varied the incremental cost-effectiveness ratio but did not change the conclusion., Conclusions: Health economics assessment showed that, compared with DSBCS, ISBCS is a cost-effective procedure. This finding will be highly useful to policy-makers, decision-makers, clinicians, hospital administrators, and payers in making cost-efficient decisions., (Copyright © 2013. Published by Elsevier Inc.)

Objective: The relationship between cataract surgery wait times and rates of surgery was investigated to determine whether wait times correlate with rates of surgery., Design: Cross-sectional study., Participants: We collected 2 Ontario registries for cataract surgeries: (i) Cancer Care Ontario wait time registry; and (ii) The Ontario Health Insurance Plan billing records., Methods: Both registries were used to determine whether wait times correlated with rates of surgery, and the data were then stratified by region of the province, priority (severity) of cases, age, and sex., Results: The total number of surgeries performed between April 2, 2007, and March 31, 2008, was 65,520. The overall mean number of wait days was 69.8 days; the mean patient age was 72.5 years; and the surgery rate was 540.3 per 100,000 members of the population. For high-priority cases (priorities 1 and 2), there was a very weak inverse correlation (p = -0.27 and -0.21) between wait time and surgery rate, whereas the overall correlation between wait time and surgical rate was close to zero in both databases, regardless of the region, the patients' ages, and the patients' genders., Conclusions: This study demonstrates a very weak correlation between wait times for and rates of cataract surgery, and this should be a concern for policy makers. Further study is needed to see whether this null relationship persists over time and whether it exists for other monitored wait time procedures. Reasons for this null relationship will have to be determined and remedied as the use of wait times becomes a more widespread outcome in Canadian Healthcare., (Copyright © 2012 Canadian Ophthalmological Society. All rights reserved.)

Objective: Selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) are used to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). We report long-term follow-up data comparing SLT to ALT., Design: Follow-up of prospective randomized clinical trial., Participants: Patients with glaucoma from the practices of three ophthalmologists at the University of Ottawa., Methods: We randomized 176 eyes of 152 patients with uncontrolled IOP on maximal tolerated medical therapy (MTMT, with or without previous ALT) to undergo either SLT or ALT. Data were available for 142 eyes at 3 years, 134 eyes at 4 years, and 120 eyes at 5 years. The primary outcome was change in IOP from pretreatment baseline., Results: Comparison of baseline parameters was similar in the two groups. Lowering of IOP were similar at 3 years (SLT -6.7 ± 7.1 vs ALT -6.1 ± 5.1); at 4 years (SLT 7.0 ± 7.7 vs ALT -6.3 ± 5.0); and at 5 years (SLT -7.4 ± 7.3 vs ALT -6.7 ± 6.6). There was no statistically significant change in IOP in either of the two groups. Medication changes were equivalent in each group. A number of interventions were required in both groups, cumulatively, over the 5-year follow-up period (49 SLT and 33 ALT). Survival analysis indicated that the time to 50% failure in each group was approximately 2 years., Conclusions: The IOP-lowering effect of SLT and ALT was similar over 5 years in this group of patients with open-angle glaucoma on MTMT., (Copyright © 2011 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.)

Objective: To describe differences in axial length scan (A-scan) and ultrasound biomicroscopy (UBM) parameters in eyes with exfoliation syndrome (XFS) and occludable angles (XFSOc), XFS and open angles (XFSOp), and eyes with primary open-angle glaucoma (POAG)., Design: Cross-sectional descriptive study., Participants: Seventy-two eyes of 72 patients (mostly Caucasians) were identified through glaucoma clinics at the University of Ottawa;19 eyes had XFSOc, 31 eyes XFSOp, and 22 eyes POAG., Methods: After a detailed ophthalmic history and examination, A-scan biometry and UBM were done to assess anterior segment parameters: central anterior chamber depth (ACD), lens thickness, trabecular meshwork-iris angle, and angle opening distance (AOD). Lens/axial length factor and the relative lens position were calculated. The above measurements were compared across the 3 groups., Results: We found statistically significant differences in measurements among the groups. ACD was shallowest in eyes with XFSOc (1.88 [SD 0.07] mm), followed by XFSOp (2.37 [SD 0.05] mm), and POAG (2.64 [SD 0.08] mm). XFSOc had thicker lenses (5.28 [SD 0.09] mm) compared with the other groups: XFSOp (5.03 [SD 0.06] mm) and POAG (4.84 [SD 0.09] mm). Lens/axial length factor was highest in XFSOc (2.34 [SD 0.05] mm) versus XFSOp (2.12 [SD 0.03] mm) and POAG (2.02 [SD 0.05] mm); relative lens position was lowest in XFSOc (2.27 [SD 0.03] mm) versus XFSOp (2.31 [SD 0.02] mm) and POAG (2.36 [SD 0.03] mm)., Conclusions: Eyes with XFSOc in our study demonstrated lens thickening and shallow central ACD versus eyes with XFSOp and eyes with POAG. This suggests the possibility that cataract formation and (or) zonular weakness may contribute to the development of an occludable angle in eyes with XFS.

Case Report: A 73-year-old woman presented with bilateral generalized posterior keratoconus. The corneal thickness measured 0.320 mm paracentrally and 0.440 mm toward the periphery. The corneal specimen revealed absence of Bowman's layer and focal homogeneous oval stromal deposits that stained for amyloid., Comments: Our case of generalized posterior keratoconus shows absence of Bowman's layer. The amyloid deposits, which also were noted clinically in the cornea of the fellow right eye, were most consistent with a diagnosis of polymorphous amyloid degeneration. To our knowledge, this is the first histopathological report of generalized posterior keratoconus.

Background: This study was undertaken to determine whether a difference exists in treatment outcome between patients treated with tranexamic acid (TEA) plus topical steroids and those treated with topical steroids alone., Methods: A retrospective cohort study was conducted to compare treatment results for children with traumatic hyphema treated with TEA and topical steroids versus topical steroids alone. Patients were identified from a chart review of the Children's Hospital of Eastern Ontario eye clinic and the Queen's Department of Ophthalmology emergency eye clinic for charts coded "traumatic hyphema." The primary outcomes measured included visual acuity, rebleed rate, intraocular pressure, and time to hyphema resolution. Covariates were hyphema grade, the need for medications to lower intraocular pressure, and the presence of associated ocular traumatic complications. Analysis was performed with both bivariate analysis and multivariate models., Results: Two hundred and fifteen patients with traumatic hyphema were included in our study. One hundred and thirty-seven patients (63.1%) received TEA plus topical steroids, and the remaining 78 patients received topical steroids alone. There was no significant difference in rebleed rate between the TEA plus topical steroid group (1.6%) and the steroid-alone group (2.6%, p = 0.60)., Interpretation: Patients with traumatic hyphema treated with TEA plus topical steroids did not have a significantly lower incidence of rebleed than those treated with topical steroids alone.

Background: The objective of this study was to perform an economic analysis of the cost-effectiveness of prostaglandin analogues for the treatment of increased intraocular pressure (IOP). Prostaglandin analogues for ophthalmic use are more costly than alternative agents for the lowering of IOP. An important policy decision is whether to support continued open listing of these agents or to restrict them to limited use status., Methods: The cost-effectiveness of prostaglandin analogues was assessed using a decision analytic model. Latanoprost was compared with timolol, dorzolamide, and brimonidine, and travoprost was compared with timolol separately. The effectiveness data used for this economic analysis were the number of millilitres of mercury of IOP reduction compared with baseline and the incidence of adverse events resulting in a withdrawal of the patient from the study. Sensitivity analyses were conducted to assess the robustness of the study results., Results: Compared with latanoprost, dorzolamide was not a cost-effective strategy. Compared with brimonidine, latanoprost provided a higher IOP reduction with an incremental cost-effectiveness ratio of $16.17 (base case), but the additional IOP reduction with latanoprost was obtained at a cost higher than the average cost per millimetre of mercury reduction obtained with brimonidine. Compared with timolol, latanoprost and travoprost had a positive incremental cost-effectiveness ratio of $34.48 and $39.06, respectively., Interpretation: For the first-line treatment of glaucoma and elevated IOP, latanoprost is a more cost-effective strategy than dorzolamide and brimonidine. Latanoprost and travoprost are more effective than timolol but also more expensive. For those for whom timolol is not contraindicated, it would be preferable, from a cost-effectiveness standpoint, to initiate treatment with timolol and reserve the prostaglandin analogues as an alternative treatment or as add-on therapy for patients not achieving a clinical response with timolol. Better treatment compliance associated with these analogues improves their cost-effectiveness.

Background: Conjunctival lymphoproliferative lesions have not been selected for independent analysis with newer immunohistochemical and molecular genetic techniques to highlight their unique profile., Methods: Retrospective case series examined biopsies from 16 consecutive patients with conjunctival lymphoproliferative lesions. The histopathologic, immunohistochemical, and molecular genetic features were characterized, as well as the frequency of tumour type, prognostic implications, clinical features, and treatments offered., Results: The diagnosis was lymphoma in 12 cases, atypical lymphoid hyperplasia (ALH) in 1 case, and reactive lymphoid hyperplasia (RLH) in 3 cases. The primary lymphomas consisted of 4 mucosa-associated lymphoid tissue lymphomas (MALTL), 1 follicular lymphoma (FL), 2 diffuse large B-cell lymphomas (DLBCLs), 1 lymphoplasmacytic lymphoma, and 1 T-cell lymphoma. Primary lymphomas were treated with radiation (n = 7), surgery (n = 1), and topical chemotherapy (n = 1). Complete remission was achieved in 8 of 9 primary lymphomas. Two cases of recurrence to the other conjunctiva were treated with radiation and both remained disease free. Secondary lymphomas included 2 DLBCL and 1 MALTL. Complete remission was seen in 2 patients after radiation plus chemotherapy, while the patient treated with chemotherapy alone was lost to follow-up. The 1 case of ALH presented bilaterally and achieved complete remission after topical chemotherapy treatments. The 3 RLH cases were surgically managed and 2 of the 3 recurred and were subsequently excised. Eleven lymphomas were of B-cell lineage by immunophenotyping. Molecular genetic studies of immunoglobulin heavy chain (IgH) gene rearrangement by polymerase chain reaction (PCR) showed clonal bands in 6 of 12 lymphomas, 1 of 3 RLH (polyclonal by immunophenotyping) and 1 ALH. BCL2-IgH [t(14;18)] rearrangement was seen in 8 of 12 cases (1 FL, 3 DLBCLs, 4 MALTLs) by real-time quantitative PCR., Interpretation: Conjunctival lymphomas are predominantly B-cell type with a high prevalence of MALTL. An unexpected finding was the BCL2-IgH rearrangement seen in 4 of 5 MALTL cases in our series. The significance of this remains unclear.

Background: Studies in preterm and term human infants have suggested that a dietary supply of omega-3 fatty acids is essential for optimal visual development. Several basic science studies support the hypothesis that omega-3 fatty acids may be useful therapeutic agents for pathologies of the retina and lens. As part of a systematic review of the effect of omega-3 fatty acids on eye health, the purpose of this study was to conduct a systematic review of the scientific-medical literature to appraise and synthesize the evidence for the effects of omega-3 fatty acids in preventing the development or progression of retinitis pigmentosa., Methods: A comprehensive search was undertaken in MEDLINE, PREMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Global Health, and Dissertation Abstracts. Unpublished literature was sought through manual searches of reference lists of included studies and key review articles and from the files of content experts. Searches were not restricted by language of publication, publication type, or study design. Eligibility criteria were applied to screen eligible studies on two levels. Data extraction and quality assessment were performed., Results: Six studies published between 1995 and 2004 met eligibility criteria in investigating the question of the possible value of omega-3 fatty acids in slowing the progression of retinitis pigmentosa. Meta-analysis was not performed because there was not enough available information for formal quantitative analysis., Interpretation: There are trends in improvement of some retinitis pigmentosa outcomes with omega-3 fatty acids in the higher quality studies. Clinical research is preliminary in this field, however. Accordingly, definitive answers will require significantly more observational and interventional clinical research.

Topic: What is the evidence for efficacy of dietary and/or supplemental omega-3 fatty acids in preventing age-related macular degeneration (AMD)?, Clinical Relevance: Age-related macular degeneraion is the leading cause of blindness and vision impairment in persons older than 50 years living in North America. There is no cure for AMD, and treatment does not usually restore vision but only prevents disease progression to a modest degree. omega-3 fatty acids are considered potentially important antioxidants and are being considered as an arm of the Age-Related Eye Disease Study II clinical trial., Methods/literature Reviewed: Keywords were searched in Medline, Pre-Medline, Embase, and the Cochrane Library on Ovid. There was no restriction on the year or language of publication., Results: There were 6 observational studies found, but the specific outcomes, exposures, and covariates studied all varied greatly., Conclusion: There is some clinical evidence for protection of AMD from omega-3 fatty acids. However, the results are not consistent. Hence, our conclusion is that this issue is neither clearly supported nor refuted by the present world literature. This is an intriguing and extremely important question but needs further study first with prospective cohort designs and, if positive, randomized clinical trials.

Background: A review of the literature and current practice patterns for vision rehabilitation care in Canada provide a basis for this pilot study, which was undertaken to explore related issues from the perspectives of older adults and low vision service providers. The pilot study was overseen by a number of collaborators whose names are listed at the end of this paper., Methods: Thirty people aged 60 years or older who had vision impairments and were clients of the Canadian National Institute for the Blind were surveyed by telephone. Ophthalmologists, optometrists, and opticians completed a mail questionnaire. Vision rehabilitation practitioners and nurses, ophthalmic technicians, and service providers for low vision technical aids were surveyed by e-mail., Results: Ophthalmologists are a primary source of referrals to low vision services, but low functional vision does not always trigger such referrals, nor are referrals always timely. Optometrists are primary providers of low vision services, including dispensing of low vision aids, but such aids are expensive, and inadequate training in their use may contribute to noncompliance. Costs associated with providing low vision assessments and services are higher than compensation to vision service providers, whose capacity to meet increasing demand is limited. In addition, there are disparities between rural and urban areas and among provinces in the availability of, and funding for, services and aids., Interpretation: On the basis of the findings, an emergent theory is proposed on the consequences resulting from lack of planning and standards for vision rehabilitation care. The implications of this study form the basis for further research.

Objective: To report a patient with conjunctival T-cell lymphoma, an extremely rare entity., Design: Single case report., Methods: Based on clinical examination, an excisional biopsy and immunostaining were performed on the conjunctival lesion. For management, we excised and performed triple freeze-thaw cryotherapy to the involved area, and we consulted the oncology service., Main Outcome Measures: T-cell and B-cell markers, and clinical examination of the lesion., Results: Both examination and laboratory assessment revealed no evidence of systemic involvement. Conjunctival biopsy showed expansion of the substantia propria with an infiltrate of chronic inflammatory cells (including lymphocytes, plasma cells, and eosinophils), and prominent lymphocyte exocytosis with reactive epithelial changes. The CD-45 RO (T-cell marker) was strongly positive, whereas the CD-20 (B-cell marker) was negative. The T-cell receptor gene rearrangement was positive with beta clonality, confirming the diagnosis of T-cell lymphoma., Conclusions: T-cell lymphoma is a rare but possible diagnosis of gelatinous conjunctival lesions. The oncology consultants were reluctant to treat the patient with systemic chemotherapy or radiation because extraconjunctival extension could never be documented. The answer to the question of what is the most appropriate treatment for conjunctival T-cell lymphoma remains unknown.

Background: To determine the efficacy and safety of trabeculectomy with mitomycin-C (trabMMC) compared with that of single-site phacotrabeculectomy with mitomycin-C (phacotrabMMC) in glaucoma patients at increased risk for filtering surgery failure., Methods: Eighty-five consecutive eyes that underwent trabMMC and 105 consecutive eyes that underwent phacotrabMMC were retrospectively compared up to 2 years postoperatively with respect to intraocular pressure (IOP), number of glaucoma medications, and surgical complication rates. The primary outcome was the difference in the cumulative proportion of patients meeting the target IOP range at 2 years. Secondary outcomes included mean postoperative IOP, mean IOP drop from baseline, mean number of glaucoma medications, and surgical complication rates., Results: Baseline characteristics were similar in the 2 groups and most patients had advanced glaucoma with a similar upper limit of the target IOP range (15.5 +/- 2.6 mm Hg for trabMMC vs. 15.3 +/- 2.1 mm Hg for phacotrabMMC, p = 0.56). Loss to follow-up was significant in both groups (almost 50% over 2 years). A statistically similar proportion of patients achieved their target IOP range at 1 and 2 years in both groups: the cumulative success rate at 2 years was 29.04% and 22.91% (p = 0.44) without add-on glaucoma therapy, 25.38% and 25.22% (p = 0.60) with the use of up to 2 glaucoma medications, and 30.01% and 25.17% (p = 0.81) with the use of any number of glaucoma medications, in the trabMMC and phacotrabMMC groups, respectively. Mean postoperative IOP was also similar between the 2 groups at almost all follow-up times up to 2 years (13.56 +/- 4.92 mm Hg in trabMMC vs. 13.98 +/- 4.74 mm Hg in phacotrabMMC at 2 years, p = 0.67). The mean IOP drop from baseline was significantly greater in the trabMMC group throughout the study period (-10.87 +/- 8.33 mm Hg in trabMMC vs. -6.15 +/- 7.01 mm Hg in phacotrabMMC at 2 years, p = 0.003); however, baseline IOP was also higher in the trabMMC group (26.1 mm Hg vs. 20.3 mm Hg, p < 0.0001). Serious postoperative complication rates were similarly low between the 2 groups., Interpretation: TrabMMC and phacotrabMMC may be equally safe and effective in bringing IOP to within an acceptable target range over 2 years in advanced glaucoma patients at increased risk for filtering surgery failure, although trabMMC appears to be associated with greater IOP lowering from baseline.

Case Report: This report summarizes a case of bilateral acanthamoeba keratitis in an 18-year-old male contact-lens wearer. Early diagnosis is important and combination treatment is recommended, tailored to the depth of the lesions., Comments: Treatment can be difficult, particularly since amoebic cysts are especially resistant. Surgery may be required for advanced cases. Suggestions for reducing corneal toxicity to antiamoebic therapy are included.

Background: To determine the iatrogenic risk factors for cytomegalovirus (CMV) retinitis in patients with the acquired immunodeficiency syndrome (AIDS)., Methods: The case-control study included 120 patients with CMV retinitis and 159 patients without CMV retinitis, all of whom had AIDS and CD4 counts less than 50 cells/microL at the time of diagnosis of retinitis or at the defined corresponding date in the controls. Iatrogenic risk factors studied were corticosteroid use, treatment with chemotherapy, treatment with radiotherapy, and blood transfusions., Results: Among the risk factors studied, only steroid use was predictive of CMV retinitis (odds ratio 6.41, 95% confidence interval 2.35-17.51). Based on this study, the use of steroids systemically elevated the risk of CMV retinitis.

Background: The purpose of this study was to examine the association between donor age and cornea transplant success., Methods: This retrospective cohort study comprised 116 patients who had cornea transplants performed for the first time. The primary analysis was performed to evaluate the time to graft failure as a function of donor age. Donor age was divided into 3 categories: (1) continuous, (2) younger than 65 versus 65 years and older, and (3) younger than 60 versus older than 70 years. We controlled for other variables that may affect graft outcome by multivariate modeling. The primary outcome was graft failure., Results: No statistically significant association was found between time to failure and donor age [adjusted hazard ratio: 1.004 (p = 0.68) for continuous age, 1.18 (p = 0.68) for age < 65 vs. > or = 65 years, and 2.10 (p = 0.089) for age < 60 vs. > 70 years]. However, with all model-building strategies, our results demonstrated that all hazard ratios calculated were greater than 1.00 for the older versus the younger aged groups., Interpretation: The influence of donor age on success of cornea transplants remains unresolved. Large, multicentre prospective cohort studies and randomized trials are needed to decisively determine the impact of donor age on cornea transplant success.

Background: Very few studies have investigated risk factors for cytomegalovirus (CMV) retinitis. Identifying these risk factors will have many benefits, including helping establish screening regimens, examination frequency regimens, and targeted prophylaxis with oral therapy with valganciclovir or other anti-CMV agents. The purpose of this study was to determine the laboratory-based risk factors for CMV retinitis in patients with AIDS., Methods: We conducted a case-control study involving 120 patients in whom CMV retinitis had been diagnosed in 1990-99 and 159 patients without CMV retinitis from the same period. The sampling was from a primary study base in eastern Ontario and western Quebec of patients with AIDS and CD4 counts less than 50 cells/microL at the time of diagnosis of retinitis in the case subjects or an analogous date for the control subjects. There were two components to the study. In the first component (n = 279) we examined standard-of-care laboratory tests (hematologic and nutrition variables) done during the study period. In the second component (n = 57), which was a subset of the first, we examined laboratory tests (HLA type, qualitative and quantitative CMV polymerase chain reaction [PCR] and HIV load) on stored blood samples from the eastern Ontario site. Multivariate logistic regression was used to model the data and control for confounding. We developed a systematic model-building strategy, from assumption testing to model building to model checking., Results: A low hemoglobin concentration was a statistically significant predictor of CMV retinitis (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.94-0.98). Both qualitative CMV PCR (OR 21.71, 95% CI 1.80-261.67) and quantitative CMV PCR (OR 33.03,95% CI 2.32-469.39) were strong predictors of CMV retinitis. Among the 80 HLA types tested, HLA-Bw4 (OR 11.68, 95% CI 1.29-105.82) and HLA-DRB115 (OR 9.34, 95% CI 1.14-76.41) were significant predictors of CMV retinitis, whereas HLA-Cw7 was protective against CMV retinitis (OR 0.09, 95% CI 0.01-0.67)., Interpretation: We have identified laboratory variables that elevate (or decrease) the risk of CMV retinitis. These findings may be useful to clinicians and health policy experts in developing rational guidelines for screening, examination frequency and targeted prophylaxis for patients with AIDS.

Background: Visual outcome studies have shown that laser photocoagulation may result in more favourable clinical outcomes than cryotherapy in threshold retinopathy of prematurity (ROP). Comparative refractive outcome studies have shown that patients treated with laser photocoagulation have less myopia than those treated with cryotherapy. We carried out a study to determine whether a difference in visual outcome or refraction exists in patients with threshold ROP who have been treated with cryotherapy vs. laser photocoagulation., Methods: A retrospective cohort study was conducted comparing treatment results after at least 3 years of follow-up in patients with threshold ROP treated with cryotherapy or laser photocoagulation at a tertiary care children's hospital. Visual acuity and refraction were the outcomes studied. Covariates measured were sex, gestational age and birth weight. Analysis was performed with both bivariate analysis and multivariate models., Results: Seventy-one eyes of 37 patients with threshold ROP were included in the study. Thirty-seven eyes received cryotherapy, and 34 eyes received laser photocoagulation. The mean spherical equivalent refraction was significantly lower in the cryotherapy group than in the laser photocoagulation group (-9.21 dioptres vs. -1.80 dioptres, p = 0.001). Patients in the cryotherapy group were more likely than those in the laser photocoagulation group to have against-the-rule astigmatism (odds ratio 6.86, p = 0.004). Laser photocoagulation did not significantly lower the frequency of an unfavourable visual outcome (visual acuity worse than 20/200) (p = 0.09)., Interpretation: Eyes with threshold ROP treated with laser photocoagulation were significantly less myopic and less likely to have against-the-rule astigmatism than those treated with cryotherapy.

Purpose: To determine the clinical risk factors for cytomegalovirus (CMV) retinitis in patients with AIDS., Design: A case-control study., Participants: The study included 120 patients in whom CMV retinitis had been diagnosed from 1990 through 1999 (cases) and 159 patients without CMV retinitis from the same period (controls). All individuals had AIDS and CD4 counts less than 50 cells/microl at the time of diagnosis of retinitis in the cases or on the corresponding date for the controls., Methods: Clinical risk factors were determined by history or physical examination. Confounders controlled for included CD4 count, hospital center, and a series of variables to control for confounding by drug treatment. Statistical analysis was performed by multivariate logistic regression. A systematic model-building strategy was developed from assumption testing to model building to model checking. MAIN VARIABLES MEASURED: Presence of visual symptoms, retinal microinfarctions (cotton-wool spots), history of opportunistic infections, and risk factors for human immunodeficiency virus acquisition were determined and compared in both groups., Results: The following clinical risk factors were significant predictors of CMV retinitis: flashing lights or floaters (odds ratio [OR], 11.42; 95% confidence interval [CI], 3.43 to 38.01), cotton-wool spots (OR, 2.90; 95% CI, 1.01 to 8.29), number of previous opportunistic infections (OR, 1.81; 95% CI, 1.24 to 2.64), previous nonocular CMV infection (OR, 82.99; 95% CI, 6.86 to 1004.58), previous Mycobacterium infection (OR, 3.41; 95% CI, 0.99 to 11.85), and homosexuality (OR, 2.83; 95% CI, 1.13 to 7.12)., Conclusions: Based on this study, clinical variables have been identified that elevate the risk of CMV retinitis. These findings may be useful to clinicians and health policy experts in developing rational guidelines for screening, examination frequency, and targeted prophylaxis for CMV retinitis in patients with AIDS.

Background: Several health databases contain information on blindness and visual impairment in Canada. Such databases may permit studies of the outcomes, predictors, economic costs and meta-analysis of ocular health problems and visual disability. In this paper we summarize the existing public health information on blindness and visual impairment in Canada., Methods: A systematic search was performed to find the information in three areas: health administrative databases, health surveys and registries. Both literature searching and Internet searching were performed. The institutions were notified by email or telephone that information pertaining to vision and blindness was desired. When necessary, we visited the institution to obtain the information., Results: Health administrative databases contain information on a wide cross-section of diagnoses but are usually limited in detail and seldom provide longitudinal information. Health surveys have a limited amount of systematic information on vision-related questions and rely exclusively on self-reporting. Registries exist on a wide range of visual topics. The Canadian National Institute for the Blind (CNIB) has the most comprehensive registry., Interpretation: This is the first attempt at summarizing all the public health information on blindness and visual impairment in Canada. The present population-based ocular information has numerous shortcomings. More comprehensive validation of large registries, such as that of the CNIB, is needed to provide the foundation for a longitudinal ocular surveillance system. Such a system could guide research on risk factors and the effect of treatment, economic analyses, and public policy for ocular research and service allocation.

Background: Pigment dispersion syndrome affects up to 4% of the white population. It is characterized by the presence of transillumination defects, Krukenberg's spindle and dense trabecular meshwork pigmentation. Open-angle glaucoma will develop in as many as 50% of affected patients. In this study we describe the familial occurrence of pigment dispersion syndrome in six North American pedigrees and the phenotypic characteristics with respect to pigment dispersion syndrome and glaucoma., Methods: Probands with pigment dispersion syndrome were identified in glaucoma clinics at university eye centres in Ottawa and Durham, NC. Families with two or more affected members were evaluated. All willing members in each family underwent a thorough clinical examination and were classified as affected with pigment dispersion syndrome, suspect or unaffected. The previous medical records were reviewed to obtain the past medical and ocular history, including risk factors for glaucoma., Results: All six families are white. Three families show at least two generations of affected members. Of the 43 subjects examined 58% were women. All 14 affected members showed moderate to heavy trabecular meshwork pigmentation and either Krukenberg's spindle or transillumination defects. The affected members were also considerably more myopic (mean spherical equivalent for the right eye -4.72 dioptres) than the suspect group or the unaffected group (mean spherical equivalent -0.79 D and +1.19 D respectively) (p < or = 0.001), and the intraocular pressure was higher for the affected than the unaffected group (mean for the right eye 20 mm Hg vs. 16 mm Hg) (p = 0.004). Half of those affected also had open-angle glaucoma., Interpretation: We have identified and phenotypically characterized six North American families with autosomal dominant pigment dispersion syndrome. Our ultimate goal is to identify the gene(s) that causes this disorder in order to clarify its molecular etiology and pathophysiology. This may give rise to a molecular classification of the disease as well as provide the foundation for genetic testing and new treatment approaches.

Background: Nonnecrotizing anterior scleritis may be treated with a variety of therapies, including topical steroid therapy, systemic therapy with nonsteroidal antiinflammatory drugs (NSAIDs) and systemic steroid therapy. This study was carried out to determine the efficacy of topical steroid therapy in treating diffuse and nodular scleritis., Methods: A phase I/II descriptive study was conducted. Thirty-two consecutive patients with nonnecrotizing anterior scleritis referred to a tertiary care ophthalmology cornea and uveitis practice in Ottawa were enrolled between September 1995 and February 1997. The patients received 1% prednisolone acetate, administered topically every 2 hours for at least 2 weeks. The drug was tapered off thereafter based on the clinical response. A successful treatment outcome was defined as resolution of scleritis without the need for systemic steroid or NSAID therapy by 2 months after initial presentation., Results: The 2-month success rate was 47%. Of the 17 patients in whom treatment failed, 5 (29%) still had some evidence of scleritis at 2 months despite systemic treatment with steroids. There was no difference between the two groups in the rate of first recurrence of scleritis (log-rank test)., Interpretation: Although topical steroid therapy failed in over half of the patients, a significant number were spared systemic steroid therapy with its potential side effects. Despite the moderately high failure rate, topical steroid therapy could be considered as first-line treatment for nonnecrotizing anterior scleritis, especially in cases in which the likelihood of complications from systemic steroid or NSAID therapy is high.

Objective: To help understand the pathogenesis of herpes family virus ocular infection among patients positive for HIV, the authors compared the rates of detection of herpes family virus DNA from the conjunctiva of patients who are positive and negative for human immunodeficiency virus (HIV) using the polymerase chain reaction (PCR)., Design: Cross-sectional study., Participants: The conjunctival scrapings of 30 patients positive for HIV and 30 patients negative for HIV were examined., Intervention: PCR was used to assay for the presence of herpes simplex virus type 1 (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) DNA (n = 240 samples)., Main Outcome Measure: The rate of detection of virus DNA in the two groups, controlling for age, gender, and race, was measured., Results: HSV and VZV DNA were not detected in any of the HIV-positive or HIV-negative samples. CMV DNA was detected in 20% (6 of 30) of patients positive for HIV and was undetected in control subjects negative for HIV (P = 0.01). EBV DNA was detected in 40% (12 of 30) of patients positive for HIV and in 47% (14 of 30) of control subjects negative for HIV (P = 0.58)., Conclusions: There was no difference in the frequency of detection of HSV, VZV, or EBV DNA from the conjunctiva of patients positive or negative for HIV. Only CMV DNA was detected at a significantly higher rate in the conjunctiva of patients positive for HIV compared with control subjects negative for HIV. These different rates of peripheral virus shedding may be one possible explanation for the different rates of clinical infection among the herpes family viruses among patients positive for HIV.

Objective: This study aimed to assess the efficacy and safety of hyperopic photorefractive keratectomy (PRK) and to evaluate the effect of degree of hyperopia, two epithelial removal methods, and various postoperative patient management techniques on clinical outcomes., Design: Prospective, nonrandomized, open-label clinical trial., Participants: A total of 38 patients with mean follow-up of 13.9 months (n = 65 eyes with hyperopia from +1.00 diopter [D] to +4.00 D) participated., Intervention: Hyperopic PRK with the VISX STAR Excimer Laser System was performed., Main Outcome Measures: Spherical equivalent (SE) including vector analysis of SE; uncorrected visual acuity (UCVA); best-spectacle corrected visual acuity (BSCVA); low-, medium- and high-contrast visual acuities; topography; keratometry; pachymetry; and intraocular pressure, haze, and all other potential complications were measured., Results: A total of 80% of eyes were within +/- 0.5 D and all but 1 eye (98%) were within +/- 1.0 D of intended manifest SE at 1 year. There was no induced astigmatism at 1 year. At 12 months, 72% of eyes had UCVA of 20/25 or better and 70% had achieved preoperative BSCVA, with no eye seeing worse than 20/25. These results remained constant at 18 months. There was a tendency toward regression between months 1 and 6 with stabilization of SEs between months 6 and 12. Thereafter, up to 18 months, there was some regression with a mean of +0.31 D, but the number of patients was small. There was one mild decentration and very slight decreases in mean intraocular pressure and central corneal thickness. One patient had grade 1.0 haze develop in both eyes at 12 and 18 months; all other patients experienced trace or no haze. There were no significant complications., Conclusions: The results of this study support the hypothesis that laser vision correction is safe and effective for treating low hyperopia. The predictability of the hyperopic laser vision correction procedure used in this study was very good. Other than the slower recovery of BSCVA and UCVA seen with this procedure, as compared with myopic PRK, there were no significant complications. The trend toward some later regression needs to be further evaluated in a larger number of patients. Overall, patients were very pleased with the treatment, even in the first 6 months.

Objective: The purpose of the study was to examine the incidence of ocular opportunistic infections among patients who are human immunodeficiency virus (HIV) positive compared to patients who are HIV negative., Design: The study design was a retrospective cohort study., Participants: All patients were recruited from 1984 until 1995 at the San Francisco General Hospital., Intervention: Incidences for numerous diagnoses were compared among the exposure group (HIV positive) and nonexposed control group (HIV negative)., Main Outcome Measures: The diagnoses studied were cytomegalovirus (CMV) retinitis, herpes zoster ophthalmicus, Pneumocystis carinii choroidopathy, herpes simplex keratitis, Toxoplasma retinitis, fungal retinitis, ocular syphilis, and ocular lymphoma., Results: Among the HIV-positive pool, there were 1800 patient visits with a total of 5200 person-years of follow-up. Among the HIV-negative control pool, there were 48,200 patient visits with a total of 30,100 person-years of follow-up. Incidence rates were calculated using the product-limit method, and risk ratios were calculated using the Cox proportional hazards model. Incidence rate differences were calculated using the incidence density method. Among the outcomes studied, only CMV retinitis, herpes zoster ophthalmicus, and, to a lesser extent, Toxoplasma retinitis showed both an elevated risk ratio and rate difference among patients who were HIV positive compared to patients who were HIV negative. Of the other outcomes studied, either the risk ratio, rate difference, or both were similar among patients who were HIV positive compared to patients who were HIV negative., Conclusions: Not all ocular infections seen in patients who are HIV positive should be considered opportunistic, because many occur with similar incidence among patients who are HIV negative. The biologic reasons for this will require further study.

Objective: To investigate the relation between measurements of intraocular pressure (IOP) and central corneal thickness (CCT) in myopic patients undergoing photorefractive keratectomy (PRK)., Design: Descriptive study., Setting: University-affiliated eye care centre in Ottawa., Patients: A total of 481 consecutive eyes of 318 patients with a mean preoperative refractive error of -6.50 dioptres treated with excimer PRK between March 1993 and December 1996., Outcome Measures: IOP measured by Goldmann applanation tonometry and CCT before and 3, 6, 12, 18 and 24 months after surgery., Results: CCT was a significant predictor of IOP only before PRK and 6 months after PRK (p < or = 0.05). The relation between IOP and CCT suggests corrections for CCT that are not clinically significant (0.81 mm Hg [standard error (SE) 0.33 mm Hg] and 1.00 mm Hg [SE 0.38 mm Hg] per 100 microns of corneal thinning preoperatively and at 6 months respectively). On average, there was a significant decrease in IOP after PRK (0.96 mm Hg and 1.24 mm Hg at 12 and 24 months respectively) (p < 0.05). There was a significant correlation between change in IOP and change in CCT (decrease of 2.1 mm Hg per 100 microns of corneal thinning) (p < 0.05). For a given change in CCT, individual changes in IOP were variable, with increases or decreases of more than 5 mm Hg in some cases., Conclusions: There are individual differences in IOP changes following PRK. Until further data are available we propose that the change in IOP between the preoperative visit (or the fellow eye, if healthy or untreated) and the 12-month visit be used as an individual correction factor to be applied to IOP measurements in the operated eye.

Purpose: The authors compare the incidence and clinical course of herpes simplex virus (HSV) keratitis among patients who are positive and negative for human immunodeficiency virus (HIV)., Methods: A retrospective cohort study was designed. Outcomes measured in both groups included incidence of HSV keratitis, lesion type (epithelial vs. stromal), lesion location (central vs. peripheral), treatment time, time to first recurrence, and recurrence rate., Results: There was no statistically significant difference between the groups for any of the outcomes measured except for recurrence rate. The recurrence rate was 2.48 times more frequent among patients positive for HIV (1 recurrence per 587 person-days of follow-up among patients positive for HIV vs. 1 per 1455 person-days among patients negative for HIV)., Conclusions: Except for recurrence rate, the incidence and clinical course of HSV keratitis in this study were no different among patients positive and negative for HIV.