Retinal precursors and the development of geographic atrophy in age-related macular degeneration

To determine specific retinal precursor lesions and sequence of events preceding the onset of geographic atrophy (GA) in eyes with age-related macular degeneration (AMD).

Retrospective review.

All participants in the Age-Related Eye Disease Study (AREDS) at 2 clinical centers (Devers Eye Institute, Portland, Oregon, and University of Wisconsin, Madison, Wisconsin) in whom GA initially appeared in at least one eye a minimum of 4 years after the baseline study visit.

All stereoscopic fundus photographs taken before the appearance of GA in the involved (study) eye were reviewed. Fundus features at the site of future GA were graded and recorded. Three graders reviewed photographs, with independent grading and adjudication by mutual agreement. Features graded included drusen (classified by size and confluence), focal hyperpigmentation, hypopigmentation, and refractile deposits. The time between first appearance of these features and initial appearance of GA was recorded.

Appearance of GA.

Of all AREDS participants at the 2 sites, 95 eyes of 77 developed GA at least 4 years after entrance into the study. Average time from baseline to initial appearance of GA was 6.6 years (range, 4-11). Drusen were found in 100% of eyes at the site of later developing GA, drusen >125 mum in diameter in 96% of eyes, confluent drusen in 94%, hyperpigmentation in 96%, drusen > 250 mum in 83%, hypopigmentation in 82%, and refractile deposits in 23%. Time from lesion appearance to onset of GA varied by lesion type, ranging from 5.9 years for drusen confluence to 2.5 years for hypopigmentation or refractile deposits. Lesions generally followed a uniform sequence of appearance.

By focusing on the location of initial GA appearance and then retrospectively analyzing prior photographs, we were able to identify specific precursor lesions and the most common sequence of events leading to GA formation in eyes with AMD. The progression was usually characterized by large drusen formation and development of hyperpigmentation, followed by regression of drusen, appearance of hypopigmentation, and ultimately development of GA, sometimes preceded by the appearance of refractile deposits.