LeAnn M. Weih

Cause-specific prevalence of bilateral visual impairment in Victoria, Australia ☆: The visual impairment project

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 > or =6/60 and/or <20 degrees > or =10 degrees radius field, moderate vision impairment; severe vision impairment, <6/60 > or =3/60 and/or <10 degrees > or =5 degrees radius field; and profound vision impairment <3/60 and/or <5 degrees radius field. In addition, less-than-legal driving vision, <6/12 > or =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.

Prevalence and predictors of open-angle glaucoma: results from the visual impairment project.

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.

Prevalence of amblyopia and associated refractive errors in an adult population in Victoria, Australia

The study aimed to describe the prevalence of amblyopia and associated refractive errors among an adult Australian population. The Visual Impairment Project (VIP) is a population-based study of age-related eye disease in the state of Victoria, Australia. Data were collected through standardised interviews and orthoptic and ophthalmic dilated examinations. Amblyopia was defined as best-corrected visual acuity of 6/9 or worse in the absence of any pathological cause. The participants were 3,265 urban residents and 1,456 rural residents of the VIP ranging in age from 40-92 years (mean = 59 years; 53% female). The prevalence of unilateral amblyopia was 3.06% (95% C.I. 2.59, 3.53). Amblyopia was not found to be statistically different by age group (p=0.096), gender (p=0.675), or place of birth (p=0.14). Anisometropia was statistically more common (p<0.001) in amblyopic cases (51.1%) compared to the normal population (9.7%), and 54% of amblyopic eyes had visual acuity of worse than 6/12. Amblyopia is a significant cause of unilateral reduced visual acuity in a population aged 40 years and older. Anisometropia was more prevalent and the degree of anisometropia was greater in the amblyopic group compared with the normal population. Oblique astigmatism was more prevalent in the amblyopic group compared with the normal population.

Fluoroquinolone and fortified antibiotics for treating bacterial corneal ulcers.

AIM To compare the clinical efficacy of commercially available fluoroquinolone drops with the use of combined fortified antibiotics (tobramycin 1.3%-cefazolin 5%) in treatment of bacterial corneal ulcer. METHODS The medical records of 140 patients with a diagnosis of bacterial corneal ulcer who were admitted to the Royal Victorian Eye and Ear Hospital, Melbourne, Australia between January 1993 and December 1997 were reviewed retrospectively. Final outcome and results of 138 ulcer episodes were compared between those treated initially with fluoroquinolone and those who received fortified antibiotics. Two patients had been treated with chloramphenicol. RESULTS No significant treatment difference was found between fluoroquinolone and fortified therapy in terms of final visual outcome. However, serious complications such as corneal perforation, evisceration, or enucleation of the affected eye were more common with fluoroquinolone therapy (16.7%) compared with the fortified therapy (2.4%, p= 0.02). The duration of intensive therapy was less with fluoroquinolone especially in those over 60 years of age (4 days v 6 days, p=0.01). Hospital stay was also less in the fluoroquinolone group compared with the fortified group for all patients and was significantly less with fluoroquinolone treatment (7 daysv 10 days, p=0.02) in patients in the age group over 60 years old. CONCLUSIONS Monotherapy with fluoroquinolone eye drops for the treatment of bacterial corneal ulcers led to shorter duration of intensive therapy and shorter hospital stay compared with combined fortified therapy (tobramycin-cefazolin). This finding may have resulted from quicker clinical response of healing as a result of less toxicity found in the patients treated with fluoroquinolone. However, as some serious complications were encountered more commonly in the fluoroquinolone group, caution should be exercised in using fluoroquinolones in large, deep ulcers in the elderly.

Utilisation of eye care services by urban and rural Australians

Aim: To investigate factors related to the use of eye care services in Australia. Methods: Health, eye care service use, and sociodemographic data were collected in a structured interview of participants in a population based study. All participants had a standard eye examination. Results: Men (OR 1.3 CL 1.02, 1.7), those who spoke Greek (OR 2.1 CL 1.1, 3.8) or Italian (OR 1.9 CL 1.0, 3.3), and those without private health insurance (OR 1.59 CL 1.22, 2.04) were more likely to have not used eye care services. Ophthalmology services were utilised at lower rates in rural areas (OR 0.14 CL 0.09, 0.2). Approximately 40% of participants with undercorrected refractive error, cataract, and undiagnosed glaucoma had seen either an ophthalmologist, optometrist, or both within the last year. Conclusion: Despite the similarity in prevalence of eye disease in urban and rural areas, significant differences exist in the utilisation of eye care services. Sex, private health insurance, urban residence, and the ability to converse in English were significant factors associated with eye healthcare service use. Many participants had undiagnosed eye disease despite having seen an eye care provider in the last year.

Vision impairment and older drivers: who’s driving?

Aim: To establish the association between impaired vision and drivers’ decisions to stop driving, voluntarily restrict driving, and motor vehicle accidents. Methods: Driving related questions were included in a population based study that determined the prevalence and incidence of eye disease. Stratified random cluster samples based on census collector districts were selected from the Melbourne Statistical Division. Eligible participants aged 44 years and over were interviewed and underwent a comprehensive ophthalmic examination. The outcomes of interest were the decision to stop driving, limiting driving in specified conditions, and driving accidents. The associations between these outcomes and the legally prescribed visual acuity (<6/12) for a driver’s licence were investigated. Results: The mean age of the 2594/3040 (85%) eligible participants was 62.5 (range 44–101). People with visual acuity less than 6/12 were no more likely to have an accident than those with better vision (χ2 = 0.175, p>0.9). Older drivers with impaired vision, more so than younger adults, restrict their driving in visually demanding situations (p<0.05). Of the current drivers, 2.6% have vision less than that required to obtain a driver’s licence. The risk of having an accident increased with distance driven (OR 2.57, CL 1.63, 4.04 for distance >31 000 km) but not with age. Conclusion: There was no greater likelihood of self reported driving accidents for drivers with impaired vision than those with good vision. While many older drivers with impaired vision limit their driving in adverse conditions and some drivers with impaired vision stop driving, there are a significant number of current drivers with impaired vision.

Assessment of trachoma prevalence in a mobile population in Central Australia

Trachoma is reported to be hyperendemic in Australia. This study was conducted in a desert area of Central Australia to implement and evaluate the WHO SAFE strategy to control trachoma. The aim of the study was to obtain baseline trachoma prevalence data and to determine whether a single annual visit is adequate for a treatment program targeting households with active cases in a highly mobile population. All registered residents of two Aboriginal communities were eligible for examination. Four visits over the course of 13 months were made to the communities for ocular examinations of residents present at the time of the visit. Examination, diagnosis, and grading of trachoma followed WHO guidelines. The overall examination rate was 75%, refusal rate was <1%, but approximately 50% of community residents were absent during the examination period. Prevalence varied on each visit, but the overall prevalence of active trachoma was 49% over the 13-month period. Children less than 10 years of age had the highest prevalence of active trachoma (79%), over the course of the 13 months, yet the prevalence at any one visit was approximately 60%. Trachomatous scarring was present in 23% of the population. These results suggest that many cases of active trachoma may be missed if a prevalence survey is conducted at only one point in time. Multiple examinations should be conducted to adequately establish prevalence in the population. Antibiotic treatment and health promotion campaigns need to be developed in consideration of local community dynamics.

Functional implications of vision impairment.

This study investigated the functional implications of vision impairment. A total of 508 participants in the Visual Impairment Project completed the VF‐14 questionnaire, vision‐related functional tasks, an interview, and the ophthalmic examination. Participants with less than 6 / 12 presenting acuity were more likely to report a moderate to high degree of difficulty performing VF‐14 items (odds ratios from 6 to 44). They were also more likely to be unable to recognize a 10 cent coin (OR; 7.0, 95% CL; 2.6, 19.3) or correctly read a telephone number (OR; 10.1, 95% CI; 5.6, 18.1). As demonstrated by the VF‐14 and the functional tasks administered in this study, visual impairment affects the ability of people to conduct a variety of common daily tasks.