Refractive errors in an older population: the Blue Mountains Eye Study.

OBJECTIVE: To determine prevalence and associations with refractive errors in a defined older population. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 3654 residents, aged 49-97, of the Blue Mountains, west of Sydney, Australia. METHODS: Comprehensive questionnaire and detailed eye examination, including refraction. MAIN OUTCOME MEASURES: Refractive error of phakic eyes, age, gender, and education. RESULTS: Prevalence rates were determined for myopia (15%), hyperopia (57%), and emmetropia (28%). Hyperopia prevalence was age-related, increasing from 36% in persons aged <60 years to 71 % of persons aged > or = 80 (P < 0.0001), whereas myopia prevalence decreased with age, from 21 % in persons aged <60 years to 10% of persons aged > or = 80 years (P < 0.0001). Younger myopic subjects in this population reported first wearing distance correction at a significantly younger age than older subjects, P < 0.0001. After adjustment for age, women were slightly more hyperopic (mean +0.75 diopters [D]) than men (mean +0.59 D, P = 0.0012. The gender-adjusted mean spherical error increased with age from +0.03 D in persons aged <60 years to +1.2 D in persons aged > or = 80 years (P < 0.0001). The gender-adjusted mean cylinder power also increased with age, from -0.6 D in persons aged <60 years to -1.2 D in persons aged > or = 80 years (P < 0.0001). The mean axis of astigmatism was "against the rule" in all age groups. Anisometropia increased with age, from a mean of 0.4 D in persons aged <60 to 0.9 D in persons aged > or = 80 years (P < 0.0001). Higher education was associated with myopia in men (P = 0.009) but not in women (P = 0.21) after adjustment for age. CONCLUSION: This report has documented the detailed refractive status of an older population, confirming previously described trends but also finding an apparent higher prevalence of myopia among younger members of this community.

Impact of visual impairment on use of community support services by elderly persons: the Blue Mountains Eye Study.

PURPOSE: To estimate the impact of visual impairment in older Australians on the use of community support services. METHODS: In the Blue Mountains Eye Study, 3654 people aged 49 or older were examined- 82.4% of eligible residents in an area west of Sydney, Australia. Presenting and best-corrected visual acuities were measured using a LogMAR chart. Subjects were categorized as having visual impairment if their better eye read 40 or fewer letters (20/40 or worse). Interview data included marital and other socioeconomic status measures, living status (alone or with spouse or other person), use of community support services, reliance on regular help from nonspouse family members or friends, and perceived ability to go out alone. RESULTS: After adjusting for age, gender, education, living status, walking disability, and health-related factors, for each one-line (five-letter) decrease in best-corrected visual acuity, there was a corresponding increase in reliance on community support services (odds ratio [OR], 1.17; 95% confidence interval, [CI] 1.07-1.28) or combined community and family support (OR 1.22; 95% CI, 1.12-1.32). Visually impaired persons were three times as likely to use regular support services provided by the municipality (OR 3.1; 95% CI, 1.8-5.1). A similar increased reliance on regular help from community, nonspouse family members, or friends was found. Visually impaired persons were also much more likely to state that they thought they were unable to go out alone (OR 6.2; 95% CI, 2.6-14.3). The findings were similar when presenting visual acuity was used to define visual impairment or after subjects with walking disabilities were excluded. Visual impairment seemed to have a greater effect on use of community support services in women than in men. CONCLUSIONS: After adjustment was made for confounding factors, visual impairment was found to affect significantly and negatively the independence of elderly people, particularly older women. Presenting visual acuity closely approximated best-corrected visual acuity in its impact on the use of community support services.

Prevalence of diabetic retinopathy in an older community. The Blue Mountains Eye Study.

OBJECTIVE: This study aimed to determine the prevalence and characteristics of diabetic retinopathy (DR) in a defined older Australian population. DESIGN: A total of 3654 persons 49 years of age or older, 88% of permanent residents from an urban area west of Sydney, underwent a detailed eye examination. This included detailed medical history, Zeiss stereo retinal photography, fasting blood glucose, and other blood factors. The diagnosis of DR was made clinically and from photographic grading in persons with a history or biochemical evidence of diabetes. RESULTS: Diabetes was present in 7% (95% confidence interval, 6.2-7.8) of the population. Signs of DR were found in 82 participants (2.3%; 95% confidence interval, 1.9-2.8). The prevalence was 1.7% in persons younger than 60 years of age, 2.4% in persons 60 to 69 years of age, 2.7% in persons 70 to 79 years of age, and 2.3% in persons 80 years of age or older. There was no significant gender difference in prevalence. After adjusting for age, gender, and the duration since diagnosis of diabetes, higher blood glucose was related to the finding of moderate-to-severe retinopathy (Wisconsin levels 4-7) compared to milder retinopathy (Wisconsin levels 1.5-3). No association was found between the presence of any retinopathy and blood glucose, a history of hypertension or elevated blood pressure, body-mass index, blood lipids, creatinine, or coagulation factors. CONCLUSIONS: This Australian study has found similar prevalence rates for DR to a recent U.S. population-based study but lower rates for vision-threatening retinopathy than from clinic-based reports. Previous reports of a relationship between advanced retinopathy and blood glucose were supported. Other than diabetes duration and insulin treatment, no other associations with retinopathy were found.

Prevalence and causes of amblyopia in an adult population.

OBJECTIVE: The study aimed to determine the prevalence, causes, and associations with amblyopia in a defined older population. DESIGN: In a population-based study, 3654 persons 49 years of age or older from an area west of Sydney, Australia, underwent a detailed eye examination and history, including objective and subjective refraction, cover testing, and retinal and lens photography. Amblyopia was diagnosed in eyes with reduced best-corrected visual acuity in the absence of any other cause. RESULTS: Amblyopia was diagnosed in 118 participants, or 3.2% of the population using a visual acuity criterion of 20/30 or less and 2.9% using a visual acuity criterion of 20/40 or less. Using a two-line visual acuity difference between the eyes, the amblyopia prevalence was 2.6% and 2.5%, respectively, for the above criteria. The underlying amblyogenic causes assessed were anisometropia (50%), strabismus (19%), mixed strabismus and anisometropia (27%), and visual deprivation (4%). The visual acuity of the amblyopic eye was 20/200 or worse (19%), 20/80 to 20/160 (19%), 20/40 to 20/63 (52%), and 20/30 (11%). No statistically significant associations were found between amblyopia and gender or eye affected. The most frequent pattern of strabismus was esotropia, whereas hypermetropia was the most frequent refractive error in amblyopic eyes. The mean age at diagnosis was earlier for strabismic and mixed amblyopia (7.4 years) than for anisometropic amblyopia (12.7 years). CONCLUSION: This study has provided prevalence and cases of amblyopia in an older population. Amblyopia is a frequent cause of lifelong unilateral visual impairment.

Visual impairment and falls in older adults: the Blue Mountains Eye Study.

OBJECTIVES: To examine the association between visual impairment and falls in older people. DESIGN: Cross-sectional survey of eye disease with retrospective collection of falls data. SETTING: Two postcode areas in the Blue Mountains west of Sydney, Australia. PARTICIPANTS: All people 49 years of age and older were invited to participate, 3654 (82.4%) of 4433 eligible residents took part, and 3299 answered questions about falls. MEASUREMENTS: Subjects had a detailed eye examination and answered questions about health and vision status, use of medication, and number of falls in the previous 12 months. RESULTS: Tests of visual function that had a statistically significant association with two or more falls after adjustment for confounders were visual acuity (prevalence ratio (PR) 1.9 for visual acuity worse than 20/30), contrast sensitivity (PR 1.2 for a 1-unit decrease at 6 cycles per degree), and suprathreshold visual field screening (PR 1.5 for 5 or more points missing). However, only visual acuity and contrast sensitivity were significantly associated with two or more falls per 1 standard deviation decrease. The presence of posterior subcapsular cataract (PR 2.1) and use of nonmiotic glaucoma medication (PR 2.0) had a statistically significant association with two or more falls; presence of age-related macular degeneration, diabetic retinopathy, and cortical or nuclear cataract did not. CONCLUSION: Visual impairment is strongly associated with two or more falls in older adults. In addition to poor visual acuity, visual factors such as reduced visual field, impaired contrast sensitivity, and the presence of cataract may explain this association.

Knowledge and beliefs about common eye diseases.

PURPOSE: To ascertain the level of knowledge of common causes of blindness in an adult Australian population and to relate this to use of eye care services. METHODS: A population-based study of common eye diseases in an urban population aged 49 years or older was conducted. The questions were concerned with the awareness and knowledge of and the ability to describe three common eye diseases, namely cataract, glaucoma and age-related macular degeneration (AMD). RESULTS: Awareness of cataract (98%) and glaucoma (93%) were high in this population, but awareness of AMD was low (20%). Among people who were aware of the target eye disease, only 29% showed some knowledge of glaucoma, 26% showed some knowledge of AMD and 20% showed some knowledge of cataract; this was also low in people who had previous eye treatment, such as cataract surgery. Knowledge was related to education level, occupational prestige and knowledge of other eye diseases. After excluding people with a previous eye disease diagnosis, those people who were aware and had some knowledge of eye disease accessed eyecare services more frequently. CONCLUSIONS: Knowledge of common eye diseases is generally lacking. Age-related macular degeneration is the leading cause of blindness in Australia, yet only 20% of the present study population had heard of it. As there are often no early symptoms for glaucoma, community awareness of this disease and the need for screening of people at risk may allow timely diagnosis and more effective therapy before advanced visual field loss has occurred. An informed public is more likely to present earlier with visual symptoms before irreversible visual loss has occurred and is more likely to comply better with recommended therapy.

Selection bias from sampling frames: telephone directory and electoral roll compared with door-to-door population census: results from the Blue Mountains Eye Study.

Many Australian public health research studies use the telephone directory or the electoral roll as a sampling frame from which to draw study subjects. The sociodemographic, disease-state and risk-factor characteristics of subjects who could be recruited using only the telephone directory or only the electoral roll sampling frames were compared with the characteristics of subjects who would have been missed using only these sampling frames, respectively. In the first phase of the Blue Mountains Eye Study we interviewed and examined 2557 people aged 49 and over living in a defined postcode area, recruited from a door-to-door census. This represented a participation rate of 80.9 per cent and a response rate of 87.9 per cent. The telephone directory was searched for each subject's telephone number and the electoral roll was searched for each subject. Subject characteristics for those who were present in each of these sampling frames were compared with the characteristics of those subjects not included in the sampling frames. The telephone directory listed 2102 (82.2 per cent) of the subjects, and 115 (4.5 per cent) had no telephone connected. The electoral roll contained 2156 (84.3 per cent) of the subjects, and 141 subjects (5.5 per cent) could not be found in either the electoral roll or the telephone directory. Younger subjects, subjects who did not own their own homes and subjects born outside of Australia were significantly less likely to be included in either of these sampling frames. The telephone directory was also more likely to exclude subjects with higher occupational prestige, while the electoral roll was more likely to exclude unmarried persons and males. Researchers using the telephone directory and electoral roll to select subjects for study should be aware of the potential selection bias these sampling frames incur and need to take care when generalising their findings to the wider community.

Prevalence of cataract in Australia: the Blue Mountains eye study.

PURPOSE: The authors determined the age and gender-specific prevalence of nuclear, cortical, and posterior subcapsular cataract (PSC) in a representative sample of older Australians. METHODS: As part of a population-based study of eye disease in the Blue Mountains, west of Sydney, 3654 people aged 49 to 96 years underwent a detailed eye examination, including lens photography (slit-lamp and retroillumination). The photographs were assessed by masked graders using the Wisconsin Cataract Grading System, with acceptable reproducibility. RESULTS: Past cataract surgery had been performed in either eye of 6.0% and in both eyes of 2.9% of participants in this study, equally in men and women. Moderate or advanced nuclear opacities were present in 53.3% of women and 49.7% of men. Moderate cortical cataract was present in 25.9% of women and 21.1% of men. Posterior subcapsular cataract was less frequent, found in 6.2% of women and 6.5% of men. After adjusting for age, these gender differences were statistically significant only for cortical cataract. The age-specific prevalence rates found for early and late cataract or for past cataract surgery are very similar to rates reported in the Beaver Dam Eye Study (BDES), Wisconsin, using the same definitions. Comparison of age-specific rates for each cataract type indicated lower rates for nuclear cataract, slightly lower rates for PSC and slightly higher rates for cortical cataract compared with the BDES. However, the rates for nuclear cataract were the only statistically significant differences between the two studies. Previously described susceptibility of the lower nasal lens to cortical cataract was confirmed, supporting a potential role of sunlight exposure in its development. CONCLUSIONS: The Wisconsin cataract grading system was used in an older Australian population with acceptable reproducibility. The Blue Mountains Eye Study found similar age-specific prevalence rates for most of the types and stages of cataract compared with the BDES.

Prevalence of open-angle glaucoma in Australia. The Blue Mountains Eye Study.

PURPOSE: The purpose of this study was to determine the prevalence of open-angle glaucoma and ocular hypertension in an Australian community whose residents are 49 years of age or older. SUBJECTS: There were 3654 persons, representing 82.4% of permanent residents from an area west of Sydney, Australia, who were examined. The population was identified by a door-to-door census of all dwellings and by closely matched findings from the national census. METHODS: All participants received a detailed eye examination, including applanation tonometry, suprathreshold automated perimetry (Humphrey 76-point test), and Zeiss stereoscopic optic disc photography. Glaucoma suspects were asked to return for full threshold fields (Humphrey 30-2 test), gonioscopy, and repeat tonometry. RESULTS: A 5-point hemifield difference on the 76-point test was found in 616 persons (19% of people tested). Humphrey 30-2 tests were performed on 336 glaucoma suspects (9.2% of population), of whom 125 had typical glaucomatous field defects. Two hundred three persons had enlarged or asymmetric cup-disc ratios (> or = 0.7 in 1 or both eyes or a cup-disc ratio difference of > or = 0.3). Open-angle glaucoma was diagnosed when glaucomatous defects on the 30-2 test matched the optic disc changes, without regard to the intraocular pressure level. This congruence was found in 87 participants (2.4%), whereas an additional 21 persons (0.6%) had clinical signs of open-angle glaucoma but incomplete examination findings. Open-angle glaucoma was thus found in 108 persons, a prevalence of 3.0% (95% confidence interval [CI], 2.5-3.6), of whom 49% were diagnosed previously. An exponential rise in prevalence was observed with increasing age. Ocular hypertension, defined as an intraocular pressure in either eye greater than 21 mmHg, without matching disc and field changes, was present in 3.7% of this population (95% CI, 3.1-4.3), but there was no significant age-related increase in prevalence. The prevalence of glaucoma was higher in women after adjusting for age (odds ratio, 1.5; CI, 1.0-2.2). There was no sex difference in the age-adjusted prevalence of ocular hypertension. CONCLUSIONS: These data provide detailed age and sex-specific prevalence rates for open-angle glaucoma and ocular hypertension in an older Australian population.

Visual acuity and the causes of visual loss in Australia. The Blue Mountains Eye Study.

BACKGROUND: The Blue Mountains Eye Study is a population-based study of vision and the causes of visual impairment and blindness in a well-defined urban, Australian population 49 years of age and older. METHODS: The logarithm of the minimum angle of resolution (logMAR) visual acuity was measured before and after refraction in 3647 persons, representing an 88% response rate in two postcode areas in the Blue Mountains area, west of Sydney. RESULTS: Refraction improved visual acuity by one or more lines in 45% of participants and by three or more lines in 13%. Visual impairment (visual acuity 20/40 or worse in the better eye) was found in 170 participants (4.7%). Mild visual impairment (Snellen equivalent 20/40 to 20/60 in the better eye) was found in 3.4% moderate visual impairment (20/80 to 20/160 in the better eye) in 0.6%, and severe visual impairment or blindness (20/200 or worse in the better eye) in 0.7%. Visual impairment increased with age from 0.8% of persons 49 to 54 years of age to 42% of persons 85 years of age or older. Visual impairment was significantly more frequent in females at all ages. Among persons with severe visual impairment, 79% were female. After adjusting for age, females were less likely to achieve 20/20 best-corrected visual acuity than males (odds ratio, 0.57; confidence interval, 0.48-0.66). After adjusting for age and sex, no association was found between visual acuity and socioeconomic status. Age-related macular degeneration was the cause of blindness in 21 of the 24 persons with corrected visual acuity of 20/200 or worse. CONCLUSION: Increasing age and female sex were independent predictors of visual impairment.

Prevalence of age-related maculopathy in Australia. The Blue Mountains Eye Study.

PURPOSE: To examine the prevalence of age-related maculopathy (drusen and retinal pigmentary abnormalities) and end-stage age-related macular degeneration lesions (neovascular maculopathy or geographic atrophy) in a defined older Australian urban population. SUBJECTS: All noninstitutionalized residents 49 years of age or older who were identified in a door-to-door census of two postcode areas west of Sydney, Australia. METHODS: All participants received a detailed eye examination, including stereoscopic photographs of each macula. Two trained graders used the Wisconsin Age-related Maculopathy Grading System to assess the presence and severity of typical lesions. RESULTS: A marked age-related increase in all typical lesions of age-related maculopathy and macular degeneration was observed. End-stage age-related macular degeneration was present in 1.9% of the population, rising from 0% among people younger than 55 years of age to 18.5% among those 85 years of age or older. Soft drusen were found in 13.3% of people, with distinct drusen more frequent than indistinct soft drusen. Retinal pigmentary abnormalities were found in 12.6% of people. For end-stage lesions and soft drusen, females had higher age-specific prevalence rates than males, whereas retinal pigmentary abnormalities were more frequent in males, although most of these differences were not significant. Prevalence rates for all lesions were lower (statistically significant for retinal pigmentary abnormalities and soft drusen) than for the United States Beaver Dam Eye Study which examined a similar population. CONCLUSIONS: These data provide detailed prevalence rates for most components of ARM in an Australian population and reinforce the Beaver Dam Eye Study findings for the relative age-specific frequency of age-related macular degeneration components.