Ophthalmology (Eye & Ear Hospital) - Research Publications
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ItemCholesterol-lowering medications reduce the risk of age-related maculopathy progression(Australasian Medical Publishing, 2001-09)Age-related macular degeneration (AMD) is the leading cause of blindness in elderly Australians. Currently, there are limited treatment options, and current research efforts are focused on determining the risk factors for AMD and developing effective treatment strategies. Some risk factors for cardiovascular disease have been shown to be associated with AMD, and one study has suggested that Alzheimer's disease is associated with age-related maculopathy. It has also been suggested that alleles of the apolipoprotein E (ApoE) gene may be associated with AMD, cardiovascular disease and Alzheimer's disease. Given this, it is interesting that statins - cholesterol-lowering medications - have been shown to decrease the risk of dementia and diabetes mellitus.
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ItemCorrection of refractive error in the Victorian population: the feasibility of "off the shelf" spectacles(British Medical Association, 2001)Aims - To assess the feasibility of providing a stock of ready made spectacles for correction of refractive error in the general population. Methods - Data were collected in the Visual Impairment Project, a population based survey of Victorian residents aged 40 years or older in randomly selected urban and rural sample areas. This included a refractive eye examination and the proportion of subjects with hypermetropia, emmetropia (defined as -1.0 to +1.0D spherical equivalent), and myopia documented in the 40-60 year age group. Results - 2595 (54.8%) participants were aged between 40 and 60 years. Those with a best corrected visual acuity of less than 6/12, astigmatism of more than 1.25D, and anisometropia of more than 0.5D were excluded. 516 participants had refractive error which was deemed suitable for correction by “off the shelf” spectacles. This represents 19.9% of all participants between 40 and 60 years of age. Provision of spectacles in 0.5D increments would provide suitable stock spectacles for 85.5% of a -3.0 to +3.0D range or 89.2% of a -3.50 to +3.50D range. Conclusions - Ready made “off the shelf” spectacles could significantly alleviate visual morbidity due to refractive error in up to 20% of an urban population in Australia. This approach may also be useful in developing countries with poor access to optometric services.
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ItemPrevalence and predictors of open-angle glaucoma : results from the Visual Impairment Project(Elsevier (American Academy of Ophthalmology), 2001-11)Purpose: To determine the prevalence and investigate predictors of open-angle glaucoma in Victoria, Australia Design: Two-site, population-based cross-sectional study. Participants: Permanent residents aged 40 years and older at recruitment from 1992 through 1996. Methods: A cluster-stratified random sample of 4744 participants from two cohorts, urban and rural, participated. Participants completed a standardized interview regarding demographic, lifestyle, and medical characteristics and a dilated eye examination including measurement of intraocular pressure, visual fields, cup-to-disc ratios, and paired stereo photography of the optic discs. A consensus panel of six ophthalmologists determined glaucoma diagnosis. Main Outcome Measure: Diagnosis of glaucoma (possible, probable, definite). Results: The prevalence of possible glaucoma cases was 1.2% (95% confidence interval [CI], 0.60, 1.7), of probable cases was 0.70% (95% CI, 0.39, 1.0), and of definite cases was 1.8% (95% CI, 1.4, 2.2). There was a significant increase in glaucoma prevalence with age across all definitions, but there was no difference in age-standardized rates between genders. A total of 60% of probable and definite glaucoma cases were undiagnosed before this study. Adjusted for age, the strongest risk factor for glaucoma was a positive family history of glaucoma (odds ratio, 3.1; 95% CI, 1.6, 5.3). Glaucoma patients who had not attended an eye care provider in the last 2 years were eight times (95% CI, 3.2, 20.4) more likely to have undiagnosed disease. Conclusions: These results support the importance of the genetic or familial basis of many glaucoma cases and highlight the need to develop appropriate techniques to screen for undiagnosed disease.
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ItemRisk factors for age-related maculopathy: the Visual Impairment Project(American Medical Association, 2001-10)Objective: To describe the risk factors and associated population attributable risk for age-related maculopathy (ARM) and age-related macular degeneration (AMD) in Australians aged 40 years and older. Methods: Residents were recruited from 9 randomly selected urban clusters and 4 randomly selected rural clusters in Victoria, Australia. At locally established test sites, the following information was collected: visual acuity, medical and health history, lifetime sunlight exposure, dietary intake, and fundus photographs. Age-related maculopathy and AMD were graded from the fundus photographs using an international classification and grading system. Backwards logistic regression was used to identify the independent risk factors for ARM and AMD. Results: The participation rate was 83% (n=3271) among the urban residents and 92% (n=1473) among the rural residents. Gradable fundus photographs of either eye were available for 4345 (92%) of the 4744 participants. There were 656 cases of ARM, giving a weighted prevalence of 15.1% (95% confidence limit [ CL] , 13.8, 16.4 ); and there were 30 cases of AMD, giving a weighted prevalence of 0.69% (95% CL, 0.33, 1.03). In multiple logistic regression, the risk factors for AMD were as follows: age (odds ratio [OR], 1.23; 95% CL, 1.17, 1.29), smoked cigarettes for longer than 40 years (OR, 2.39; 95% CL, 1.02, 5.57), and ever taken angiotensin-convening enzyme inhibitors (OR, 3.26; 95% CL, 1.33,8.01 ). The magnitude of all of these risk factors was slightly less for ARM, and having ever taken blood cholesterol-lowering medications was also significant (OR, 1.67; 95% CL, 1.12, 2.47; P=.001). Conclusion: Smoking is the only modifiable risk factor for ARM and AMD, among the many environmental and systemic factors that were assessed.
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ItemIntraocular pressure before and after cataract surgery in participants of the Melbourne Visual Impairment Project( 2001)The purpose of this study was to investigate the effect of cataract surgery on intraocular pressure (IOP) in a cluster stratified random sample of the population of Victoria, Australia. A total of 3271 participants aged 40 years or older were examined at baseline for the Visual Impairment Project. The baseline study (1992-1994) was followed by a 5-year incidence study. The IOP data were compared between participants who had cataract surgery between the two stages of the study and participants with and without cataract at follow up. The IOP was also compared before and after cataract extraction in glaucoma participants. An eligible 89 non-glaucoma and 24 glaucoma participants had cataract surgery between the two time points. The analyses showed that IOP increases with age in non-operated eyes in both glaucoma and non-glaucoma groups. However, IOP decreased significantly after cataract surgery in eyes with glaucoma but did not change significantly in non-glaucoma participants.
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ItemCause-specific prevalence of bilateral visual impairment in Victoria, Australia: the Visual Impairment Project(Elsevier (Initially -American Academy of Ophthalmology), 2001)Purpose: To study the cause-specific prevalence of eye diseases causing bilateral visual impairment in Australian adults. Design: Two-site, population-based cross-sectional study. Participants: Participants were aged 40 years and older and resident in their homes at the time of recruitment for the study. The study was conducted during 1992 through 1996. Methods: The study uses a cluster stratified random sample of 4744 participants from two cohorts, urban, and rural Victoria. Participants completed a standardized interview and eye examination, including presenting and best-corrected visual acuity, visual fields, and dilated ocular examination. The major cause of vision loss was identified for all participants found to be visually impaired. Population-based prevalence estimates are weighted to reflect the age and gender distribution of the two cohorts in Victoria. Main Outcome Measures: Visual impairment was defined by four levels of severity on the basis of best-corrected visual acuity or visual field: <6/18 ≥6/60 and/or <20° ≥10° radius field, moderate vision impairment; severe vision impairment, <6/60 ≥3/60 and/or <10° ≥5° radius field; and profound vision impairment <3/60 and/or <5° radius field. In addition, less-than-legal driving vision, <6/12 ≥6/18, and/or homonymous hemianopia were defined as mild vision impairment. In Australia, legal blindness includes severe and profound vision impairment. Results: The population-weighted prevalence of diseases causing less-than-legal driving or worse impairment in the better eye was 42.48/1000 (95% confidence interval [CI), 30.11,54.86). Uncorrected refractive error was the most frequent cause of bilateral vision impairment, 24.68/1000 (95% CI, 16.12, 33.25), followed by age-related macular degeneration (AMD), 3.86/1000 (95% CI, 2.17,5.55); other retinal diseases, 2.91/1000 (95% CI, 0.74, 5.08); other disorders, 2.80/1000 (95% CI, 1.17,4.43); cataract, 2.57/1000 (95% CI, 1.38, 3.76); glaucoma, 2.32/1000 (95% CI, 0.72, 3.92); neuro-ophthalmic disorders, 1.80/1000 (95% CI, 0, 4.11); and diabetic retinopathy, 1.53/1000 (95% CI, 0.71,2.36). The prevalence of legal blindness was 5.30/1000 (95% CI, 3.24, 7.36). Although not significantly different, the causes of legal blindness were uncorrected refractive errors, AMD, glaucoma, other retinal conditions, and other diseases. Conclusions: Significant reduction of visual impairment may be attained with the application of current knowledge in refractive errors, diabetes mellitus, cataract, and glaucoma. Although easily preventable, uncorrected refractive error remains a major cause of vision impairment.
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ItemAssessment of adult stereopsis using the Lang 1 Stereotest: a pilot study( 2001)Background and Purpose: To assess the use of the Lang 1 Stereotest as a vision-screening test for adults, for which little is known or reported. Method: The Lang 1 Stereotest was administered to 292 consecutive participants of the Visual Impairment Project (VIP) five year followup study, which is a population based study of eye disease in Melbourne, Australia. 56.9% were female. The mean age was 59.4 years, range 44-90 years. A "positive" stereoscopic response was recorded where the stereoscopic target image was correctly named; a "partial positive" response where depth was appreciated but the shape could not be named; and a "negative" response where there was no appreciation of a stereo effect. The responses were further categorized so that the test was either "passed" or "failed". A "pass" score was 3/3 positive responses; 3/3 partial positive responses or 2/3 positive and/or partial positive responses where the negative response was at the 550" of arc stereoacuity level. "Failure" was 3/3 negative responses and 2/3 negative responses where the positive or partial positive response as at the 1200" level. (For complete abstract open document)
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ItemDiabetic retinopathy in Victoria, Australia: the Visual Impairment Project( 2001)The aim of this study was to establish the prevalence, severity, and risk factors for diabetic retinopathy in a representative sample of Victorian residents aged >= 40 years.A population-based cluster sampling method was used to recruit 4,744 participants (86% participation rate) between 1992 and 1996. Nine suburban Melbourne clusters and four rural Victorian clusters were randomly selected. A private household census was conducted to identify permanent household members aged >= 40 years who were classified as eligible residents. At locally established test sites, participants provided a detailed medical and personal history and underwent an ocular examination including dilated funduscopy and fundus photography. The interview included specific questioning about whether participants had ever been diagnosed with diabetes mellitus and the year in which such a diagnosis was made. Participants with previously diagnosed diabetes were also asked if and when their last dilated fundus examination had been conducted and who performed the examination. Two 30° fields of the fundus were photographed in each eye; one centered on the optic disk and the other centered on the fovea. Levels of diabetic retinopathy in people with previously diagnosed diabetes were defined, according to the Academy of Ophthalmology in the United States, as mild nonproliferative, moderate nonproliferative, severe nonproliferative, and proliferative diabetic retinopathy. All participants at rural test sites were asked to provide a finger-prick blood sample to measure glycosylated hemoglobin (HbAlc) percentages. Glaucoma status was evaluated by a consensus panel comprised of six ophthalmologists, including two glaucoma specialists. This panel determined glaucoma status on the basis of Humphrey visual fields and photographs of the optic disk. Presenting visual acuity was determined with an Early Treatment Diabetic Retinopathy Study 4-meter chart. Myopia was defined as a best-corrected minus spherical equivalent of > -0.5 D in either eye.