The progression of cataract and the rate of cataract surgery over five years in the Icelandic population–Reykjavik Eye Study–

Abstract

Abstract: : Purpose: To provide five–year progression rate of age–related lens opacities and the rate of cataract surgery in the Icelandic population > 50 years of age. Methods: The Reykjavik Eye Study (RES) is a population based study using the population census. Of the 1045 subjects who participated in the RES in 1996, 846 (376 males and 470 females, Mean age 69.1±9.0 years old) or 88.2% of the 959 survivors were reexamined five years later in 2001. Changes in the crystalline lens were photographed by an Anterior Eye Segment Analysis System (EAS–1000, NIDEK) under maximal pupillary dilation and examined. Classification of nuclear (N), cortical (C), cortical opacity within a 3mm diameter of the pupil (CEN) and posterior subcapsular cataract (S) were determined from the photographed images by a single observer using the simplified cataract classification and grading system established by the WHO for both baseline and follow–up photographs. Cumulative progression was defined by any increase in grade of preexisting lens opacity. For data analysis, student's t–test, Χ²–test and Mantel–Haenszel tests were applied. Results: The five–year progression rates were 39.2% for N, 22.7% for C and 33.3% for S, respectively. No increasing tendency with aging was observed for the progression rates of all three types. The prevalence of aphakia or pseudophakia in 2001 in one or both eyes was 5.0% (4.1% in males and 5.8% in females). The prevalence by age was 0% in 50s, 0.7% in 60s, 7.1% in 70s and 20.0% in 80s and over. The rate of cataract surgery in the five–year period was 16.1% for the eyes with N, 16.0% for the eyes with C and 58.8% for the eyes with S at baseline. This rate was significantly (P<0.01) higher with CEN (23.9%) than without CEN (1.7%). Conclusions: Applying the WHO system, the five–year progression rate was highest in N followed by S and C for the Icelandic population. S was the most important predictor of cataract surgery. If subjects were without CEN, very few needed to undergo cataract surgery in this five–year period.

Keywords: cataract • clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials