A myopic shift in Australian Aboriginals: 1977-2000.

BACKGROUND/AIMS: The prevalence of myopia has been reported to have increased in a number of population groups. We compared the refraction of Australian Aboriginal adults in 2000 with data collected in 1977 to assess whether there had been a change in the prevalence of myopia. METHOD: Australian Aboriginal adults aged 20 to 30 years old were selected from Central Australian communities in 2000. Refraction was determined by noncycloplegic autorefraction. This was compared to mydriatic retinoscopy data collected in 1977. "Observer trials" were undertaken to assess the comparability of noncycloplegic autorefraction measurements and cycloplegic retinoscopy. Spherical equivalence cylinder and spheric were determined for all right and left eyes and compared using an analysis of variance. RESULTS: A total of 128 adults (58 males, 70 females) were examined in 2000 and compared with 161 adults (107 males, 54 females) examined in 1977. The mean spherical equivalent in 2000 was -0.55 D +/- 0.88 D and in 1977 was +0.54 D +/- 0.81 D. The difference of -1.09 D was highly significant (F = 126, P < .001). Intraclass correlation coefficients showed good agreement between noncycloplegic autorefraction and cycloplegic retinoscopy. Neither gender, schooling, nor diabetes was associated with an increased risk of myopia. CONCLUSIONS: There appears to have been a significant shift toward myopia in Australian Aboriginals between 1977 and 2000. The cause of this myopic shift is unknown but mirrors that observed in other populations in recent years.

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 (chi(2) = 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.

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.

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.

Association of demographic, familial, medical, and ocular factors with intraocular pressure.

OBJECTIVE: To describe the distribution and associations of demographic, familial, medical, and ocular factors with intraocular pressure (IOP). METHODS: A cluster stratified random sample of urban and rural residents of Victoria, Australia, aged 40 years and older. Participants completed an interview and underwent a standardized dilated ophthalmic examination including measurement of IOP with an electronic applanation tonometer (Tono-Pen). Glaucoma status (possible, probable, definite) was determined by a consensus panel. The main outcome measure was IOP. RESULTS: The mean age of the 4576 participants was 59 years, 53% were women, 32% were born overseas, and 132 had open-angle glaucoma. Geometric mean (SD) IOP was 14.3 (+/-1.5) mm Hg. The relationship between IOP and nuclear sclerosis, iris color, and family history of glaucoma depended on glaucoma status. In those with glaucoma, family history of glaucoma and country of birth were significantly associated with IOP in multivariate models (model: r(2) = 0.08, P =.01). In the group without glaucoma, place of residence, use of alcohol, iris color, vitamin E intake, and spherical equivalent were associated with IOP (model: r(2) = 0.01, P =.006). CONCLUSION: In participants with glaucoma, genetic factors seem to be stronger predictors of IOP, whereas in those without glaucoma, lifestyle and physiological factors seem to play a greater role.

A measure of handicap for low vision rehabilitation: the impact of vision impairment profile.

This study aims to further develop the Impact of Vision Impairment (IVI) profile into a practical, valid instrument for use in low vision rehabilitation. The IVI item pool was derived from focus groups of people with impaired vision, relevant content of existing quality of life questionnaires, and the administration of two trial versions. The second trial version of IVI was administered to 256 people who were vision impaired. Items were deleted if they were of little or no concern or were unable to be performed by most people, had moderate to high inter-item correlation, or did not contribute to a factor in the factor analysis. Two items were deleted due to floor and ceiling effects, 11 due to moderate to high inter-item correlation r> or =0.6. None were removed as a result of factor analysis. The first three factors explained 59% of the variance.This reduced version of the IVI, a tool able to determine rehabilitation needs for people who are vision impaired, will now undergo its final validation procedures.

Age-specific causes of bilateral visual impairment.

OBJECTIVES: To describe the age-specific prevalence of common eye diseases causing bilateral visual impairment and estimate the total number of Australians with cause-specific visual impairment. METHODS: Cluster-stratified random sample of 5147 residents aged 40 years and older from urban and rural areas and aged-care facilities. Participants completed a standardized interview and eye examination. Four levels of bilateral visual impairment were defined: less than 20/40 to 20/60 and/or homonymous hemianopia (mild), less than 20/60 to 20/200 or better and/or less than 20 degrees to 10 degrees radius field (moderate), less than 20/200 to 10/200 and/or less than 10 degrees to 5 degrees radius field (severe), and less than 1O/ 200 and/or less than 50 radius field (profound). The major cause of vision loss was identified for all participants found to be visually impaired. RESULTS: Uncorrected refractive error was the most common cause of bilateral visual impairment across all decades of life, rising from 0.5% in 40- to 49-year-olds to 13% among those aged 80 years and older. Prevalence of visual impairment due to diabetic retinopathy was 0.7% in 50- to 59-year-olds and 0.8% in those older than 80 years. Visual impairment due to glaucoma had a prevalence of 0.7% among 60-year-olds and rose to 4% of those older than 90 years. The prevalence of visual impairment due to cataract (only present in those aged 70 years or older) rose from 0.6% to 11% in those older than 90 years, and the prevalence of visual impairment due to age-related macular degeneration rose from 0.8% to 16% in those older than 90 years. CONCLUSIONS: The predominant causes of visual impairment change with age. Recognition of these patterns is fundamental for early diagnosis and treatment of eye disease and, where appropriate, referral for rehabilitation.

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.

Patterns of glaucoma medication use in urban and rural Victoria.

PURPOSE: The purpose of the present study was to describe patterns of glaucoma medication use among people who self-report a history of glaucoma in a population-based study of age-related eye disease. METHODS: The present study was comprised of a population-based cluster stratified sample of 5000 Victorians aged 40 years and older. Participants completed an interview regarding demographic characteristics, medical history and use of medications. Participants also completed orthoptic and dilated fundus examinations, including measurement of intra-occular pressure (IOP) and visual fields. Glaucoma history and use of glaucoma medication was self reported. Glaucoma disease status was confirmed by a specialist consensus group. RESULTS: The most common glaucoma medications used were beta-adrenoceptor blocking agents (63%), followed by sympathomimetics (18%) and cholinergic agents (16%). There were no differences in glaucoma medication use by gender, age, years since diagnosis, rural or urban residence or a history of glaucoma surgery. Among participants using medication, 16.1% exceeded 21 mmHg IOP. CONCLUSION: The high prevalence of the use of beta-adrenoceptor blocking agent medication reflects the shift from the use of pilocarpine over the past 20 years. The prevalence of IOP greater than 21 mmHg highlights the difficulty in managing high IOP.

Factors associated with elevated 222Rn levels in Iowa.

The University of Iowa, in conjunction with the Environmental Protection Agency's State Radon Survey Assistance Program, performed a 222Rn screening survey of 582 rural households in the winter of 1989. The distribution of maximum indoor 222Rn concentrations throughout Iowa as well as the relationship between 222Rn screening measurements, detector placement, and housing characteristics are summarized. This report is unique in that site-specific home construction characteristics were collected in the field from participants prior to 222Rn monitoring. The findings of the survey indicate that the significance of a particular housing characteristic on a 222Rn screening measurement is dependent on the placement of the radon detector.