Abstract
Abstract: :
Purpose:Genetic linkage studies in age–related macular degeneration (AMD) often necessitate classification of individuals in younger generations into affected and unaffected status. Although extensive data exist on the prevalence of drusen in those 50 years and older, there is a paucity of data on the prevalence of drusen in the normal population aged 49 years and younger. The aim of this study is to determine the prevalence and type of drusen present in the age range 20 – 49 years. Methods: We reviewed digital retinal images from both eyes of 600 consecutive patients aged 20–49 from 2 local optometry practices. The patients had been photographed routinely as part of their examination and were therefore representative of the general population. The only data recorded with the images was date of birth and a code number for the image. The images were graded by a retinal specialist, with right eyes been graded first, then left. This was to minimise the chance of overestimating drusen in the 2nd eye of the same patient. The images were graded for the presence of drusen, the size of drusen and whether the drusen were located in the macular or extramacular area. The images were graded in age ranges of 5 years, ie: 20–24, 25–29, 30–34, 35–39, 40–44 and 45–49. Results: The prevalence of drusen was 30% in the age range 20–24 years; 35.9% aged 25–29; 23.7% aged 30–34; 35.9% aged 35–39; 47.2% aged 40–44 and 48.6% aged 45–49 years. Drusen size was predominantly < 63u with most drusen being very small: 79.5% of eyes with drusen had drusen <63um, 19.3% >63um <125um, 1.2% > 125um. The drusen were located in the macular region in 77.6% and extramacularly in 22.4% of eyes. Conclusions: These data indicate that drusen are common in those aged 20 – 49 years, however these drusen are predominantly <63um in size and in most cases much smaller than 63um. The prevalence of drusen rises noticeably in those aged over 40 years. These data which indicate a relative absence of drusen >125um in diameter in this age group in the general population, will be useful in informing the phenotyping of individuals in younger generations in genetic studies in AMD families.
Keywords: drusen • age-related macular degeneration • genetics