The Reykjavik Eye Study – Prevalence of Lens Opacification with Reference to Identical Japanese Studies

Abstract

Purpose: A population-based cataract epidemiological study, the Reykjavik Eye Study, was conducted to determine the prevalence and characteristics of lens opacities in Iceland. The results were compared with those from previous surveys in Japan to determine the influence of race and environmental factors. Methods: 1,635 randomly selected residents of Reykjavik, Iceland, were enrolled, and among them, 1,045 responded and took part in the study. The subjects received ophthalmological examination of both the anterior and the posterior segments. Changes in the crystalline lens were examined and photographed under maximal pupillary dilation. Classification of the opacity types and grading of the extent of lens opacificiation were done using a standardized scheme, and the data were analyzed with Student’s test, the χ² test and the Mantel-Haenszel test. Results: The prevalence of lens opacities in subjects in their 50s, 60s, 70s and in those 80 years and older was 42.7, 61.0, 85.3 and 100%, respectively. Grade II and III lens opacities were found in 2.2% of subjects in their 50s and in 10.5, 35.9 and 62.3% in their 60s, 70s, and over 80 years, respectively. Cortical opacities predominated in all age groups followed by nuclear opacities; subcapsular opacities, on the other hand, were quite rare. A unique type of opacity, i.e., granular opacity, seldom seen among the Japanese, was found in 6.6% of the Icelandic subjects. Conclusions: Our results show that cortical opacity is the major type of opacity in Icelandic subjects, although its prevalence was lower than that in the Japanese subjects. Interestingly, the first appearance of lens opacities of grades II and III in Icelanders was delayed by 10 years compared to the Japanese suggesting fewer or less severe risk factors for cataract formation in Iceland.

Prevalence of open-angle glaucoma in Iceland: Reykjavik Eye Study

“…A total of 6.4% people were sampled for each year of birth and both sexes. [7][8][9][10] Of those 1700 thus sampled, 1379 (81.1%) could be contacted and qualified of which 1045 (461 male and 584 females) elected to participate, giving a response rate of 75.8%. 8 All were Caucasians.…”

“…They were required to answer a questionnaire regarding lifestyle, health, previous disease, surgery, and medication. [7][8][9][10] …”

“…All participants were examined utilizing a standard examination protocol including keratorefractometry (Nidek ARK 900), air puff tonometry (Nidek NT 2000, mean of three successful measurements), 10 Scheimpflug photography of the anterior segment (Nidek EAS 1000), 7 slit-lamp examination of the anterior segment, biomicroscopy of fundi with a 78D lens, and simultaneous stereo fundus photography centred on the optic disc and another on the fovea (Nidek 3Dx/NM). On the day of survey, gonioscopy was not done since this would have interfered with Scheimpflug and fundus photography.…”

“…6 The purpose of the present study is to establish the age-and sex-specific prevalence of open-angle glaucoma (OAG), subsuming pseudoexfoliative glaucoma in the city of Reykjavik. This study is part of the Reykjavik Eye Study [7][8][9][10] that addressed the same questions for age-related lens opacification and agerelated maculopathy.…”

Racial Differences of Lens Transparency Properties with Aging and Prevalence of Age-Related Cataract Applying a WHO Classification System

“…To overcome this situation, the WHO study group proposed the newly established cataract classifi cation system [2] . For purposes of this study, and to assist other researchers to make such comparisons, from our own Japanese Cooperative Cataract Epidemiology Study Group system (JCCESG system) [3] , data of the same subjects from previous surveys [4][5][6] have been converted in accordance with the new WHO classifi cation system.…”