Prevalence and progression of visual impairment in patients newly diagnosed with clinical type 2 diabetes: a 6-year follow up study.

BACKGROUND: Many diabetic patients fear visual loss as the worst consequence of diabetes. In most studies the main eye pathology is assigned as the cause of visual impairment. This study analysed a broad range of possible ocular and non-ocular predictors of visual impairment prospectively in patients newly diagnosed with clinical type 2 diabetes. METHODS: Data were from a population-based cohort of 1,241 persons newly diagnosed with clinical, often symptomatic type 2 diabetes aged ≥ 40 years. After 6 years, 807 patients were followed up. Standard eye examinations were done by practising ophthalmologists. RESULTS: At diabetes diagnosis median age was 65.5 years. Over 6 years, the prevalence of blindness (visual acuity of best seeing eye ≤ 0.1) rose from 0.9% (11/1,241) to 2.4% (19/807) and the prevalence of moderate visual impairment (> 0.1; < 0.5) rose from 5.4% (67/1,241) to 6.7% (54/807). The incidence (95% confidence interval) of blindness was 40.2 (25.3-63.8) per 10,000 patient-years. Baseline predictors of level of visual acuity (age, age-related macular degeneration (AMD), cataract, living alone, low self-rated health, and sedentary life-style) and speed of continued visual loss (age, AMD, diabetic retinopathy (DR), cataract, living alone, and high fasting triglycerides) were identified. CONCLUSIONS: In a comprehensive assessment of predictors of visual impairment, even in a health care system allowing self-referral to free eye examinations, treatable eye pathologies such as DR and cataract emerge together with age as the most notable predictors of continued visual loss after diabetes diagnosis. Our results underline the importance of eliminating barriers to efficient eye care by increasing patients' and primary care practitioners' awareness of the necessity of regular eye examinations and timely surgical treatment.

Prevalence and causes of visual impairment and blindness among 9980 Scandinavian adults: the Copenhagen City Eye Study.

PURPOSE: To investigate the age-specific prevalence and causes of visual impairment and blindness in an epidemiologic study of an adult Scandinavian population. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: The study population was composed of 9980 persons, ages 20 to 84, from the general population of Copenhagen, Denmark. METHODS: This study is based on the third Copenhagen City Heart Study (CCHS III). Participants who reported visual impairment or blindness or had difficulty reading newspaper type and used prescribed eye medications were contacted from 1999 through 2000 and asked to complete a standardized interview concerning their ophthalmologic history. Verification of objective ophthalmologic data was done with a validated questionnaire response method. MAIN OUTCOME MEASURES: Best-corrected visual acuity in the better eye and primary causes of visual impairment and blindness. Visual impairment was defined as visual acuity worse than 20/40 but better than 20/200, and blindness was defined as visual acuity of 20/200 or worse. RESULTS: The age-standardized prevalence rates of visual impairment and blindness were 0.66% and 0.20%, respectively, and rose significantly with age (P<0.001). For persons 20 to 64 years, myopia-related retinal disorders, diabetic retinopathy, optic neuropathy, and retinitis pigmentosa were the most common causes of impaired vision. For persons 65 to 84 years, cataract was the most common cause of visual impairment, whereas age-related macular degeneration was the major cause of blindness. CONCLUSIONS: Visual impairment and blindness are strongly associated with increasing age, and the causes are determined by age. Among persons aged 20 to 64 years, an intervention for the predominating eye diseases might have some effect. Among those aged 65 to 84 years, cataract surgery could reduce visual impairment by one third.