Prevalence and causes of visual impairment and blindness in Icelanders aged 50 years and older: the Reykjavik Eye Study

Purpose: This study aimed to study the prevalences and causes of visual impairment and blindness in an Icelandic adult population. Methods: The Reykjavik Eye Study includes a random sample of citizens of Reykjavik aged ≥ 50 years, with an equal proportion (6.4%) for each year of birth and each sex. A total of 1045 persons were examined, representing a response rate of 75.8%. All participants underwent an extensive ophthalmological examination using a standard protocol. We used World Health Organization (WHO) definitions for bilateral visual impairment (best corrected visual acuity [VA] < 6/18 or visual field of ≥ 5 ° and < 10 ° around the fixation point in the better eye) and blindness (VA < 3/60 or visual field < 5 ° in the better eye). We also used US criteria, which define bilateral visual impairment as present if VA is < 6/12 and blindness as present if VA is ≤ 6/60 (both in the better eye). The causes of visual loss were determined for all participants found to be visually impaired in one or both eyes. Results: The prevalences of bilateral visual impairment and blindness were 0.96% (95% confidence interval [CI] 0.37–1.55) and 0.57% (95% CI 0.12–1.03), respectively, using the WHO criteria, and 2.01% (95% CI 1.16–2.86) and 0.77% (95% CI 0.24–1.29), respectively, using the US criteria. The prevalence rates were 4.40% and 5.45% for unilateral visual impairment and 1.72% and 3.06% for unilateral blindness, using the WHO and US criteria, respectively. Age‐related macular degeneration (AMD) was the major cause of bilateral visual loss, whereas the most common causes of unilateral visual loss were, in this order, amblyopia, cataract and glaucoma. Conclusions: Prevalence of visual loss increases with age. The leading cause of bilateral visual impairment and blindness was AMD, accounting for more than half of all cases, and cases of geographic atrophy outnumbered those of exudative AMD by two to one.     

Risk factors for five-year incident age-related macular degeneration: the Reykjavik Eye Study

PURPOSE: To establish risk factors for five-year incidence of age-related macular degeneration (AMD). DESIGN: Population-based, prospective cohort study, and risk analysis. METHODS: A random sample from the Reykjavik Population Census for individuals 50 years and older was selected. We took fundus stereo color photographs and used standard grading system to study the five-year incidence of drusen, pigmentary abnormalities, and AMD and to examine possible risk factors. A questionnaire including information on disease, medication, diet, and lifestyle from the Reykjavik Eye Study database provided additional information. RESULTS: Current alcohol consumption decreased the risk for drusen. Being married rather than divorced or widowed decreased the risk for soft drusen; being single decreased the risk of hypopigmentation as compared with being divorced or married. Both consuming dietary fiber-rich vegetables and meat and meat products once a week or less frequently was a risk factor for developing soft drusen and decreased the risk of pigmentary abnormalities. Those who had smoked 20 pack-years or more as compared with nonsmokers had decreased survival rate over the five years (odds ratio (OR) 0.46, 95% confidence interval (CI) 0.27 to 0.80; P = .006). CONCLUSIONS: Risk factors for drusen appear to differ from risk factors for pigmentary abnormalities. The effect of smoking on developing AMD is partly masked by selective mortality.     

Central corneal thickness, radius of the corneal curvature and intraocular pressure in normal subjects using non-contact techniques: Reykjavik Eye Study

PURPOSE: To establish a population profile of central corneal thickness (CCT), radius of the corneal curvature (CC) and intraocular pressure (IOP) and the relationships between them using non-contact techniques. METHODS: We used a population-based random sample of 415 male and 510 female Caucasians aged 50 years and older. CCT and the radius of CC were measured with Scheimpflug anterior segment photography. IOP was measured with air-puff tonometry. RESULTS: The mean IOP of right eyes was 15.1 mmHg (SD 3.3) among men and 15.8 mmHg among women (SD 3.1), which is a statistically significant difference. The mean radius of CC for male right eyes was 7.78 (SD 0.60) and for females 7.62 (SD 0.58) which is also statistically significant. Mean CCT for male right eyes was 0.528 mm (SD 0.041) and for females 0.526 mm (SD 0.037), which is not a significant difference. Linear regression analysis shows no relationship between the radius of CC and IOP or between age and radius of CC. Linear regression analysis of the relationship between CCT and IOP suggests higher IOP measurements with thicker corneas. There was no significant correlation between age and CCT. CONCLUSION: IOP was found to be independent of age and significantly higher in females than in males. Radius of CC was found to be age-independent and significantly steeper in females than in males. CCT appears to be independent of age and gender. Greater CCT is associated with higher mean IOP.     

Five‐year incidence of visual impairment and blindness in older Icelanders: the Reykjavik Eye Study

Purpose: This study examined age, sex and cause‐specific 5‐year incidence of visual impairment and blindness in a middle‐aged and elderly Icelandic population. Methods: The study cohort consisted of a population‐based, random sample of citizens aged ≥ 50 years. Of 1379 eligible subjects, 1045 underwent a baseline examination in 1996; 846 of the 958 survivors (88.2%) underwent a 5‐year follow‐up examination in 2001. All participants underwent an extensive ophthalmological examination including best corrected visual acuity (BCVA) using a Snellen chart. We used World Health Organization (WHO) criteria, which define visual impairment as BCVA in the better eye of < 6/18 and ≥ 3/60 and blindness as BCVA in the better eye of < 3/60. We also used US criteria, which consider BCVA of < 6/12 and > 6/60 in the better eye to represent visual impairment and BCVA of ≤ 6/60 in the better eye to represent blindness. The causes of incident visual loss in either eye were determined. Deterioration or improvement in vision were defined as a loss or gain of ≥ 2 Snellen lines. Results: According to WHO criteria, 5‐year incidence of bilateral visual impairment and blindness were 1.07% (95% confidence interval [CI] 0.37–1.76) and 0.35% (95% CI 0.00–0.76), respectively. Using US criteria, equivalent incidence of bilateral visual impairment and blindness were 3.49% (95% CI 2.24–4.74) and 0.95% (95% CI 0.29–1.60), respectively. Age‐related macular degeneration and cataract were the major causes of incident visual impairment and blindness. Conclusions: Incidences of visual impairment and blindness increased significantly with age. Age‐related macular degeneration, present in 75% of affected persons, was the most common cause of 5‐year incident legal blindness in this middle‐aged and elderly Icelandic population.