At first presentation, more than 30% of incident geographic atrophy (GA) was within the foveal region, and patients with extrafoveal GA developed it within the fovea after approximately 5 years, according to findings published in JAMA Ophthalmology.
Researchers analyzed data from 4 population-based, cohort studies conducted between 1990 and 2015 to determine the long-term enlargement of GA. The study data included up to 25 years of follow-up and eye examinations at 5-year intervals, and the data were analyzed from January 2019 to November 2020.
The study measured GA pixel by pixel using all available imaging, and it assessed area enlargement and enlargement of the square root-transformed area, time until GA reached the central fovea, time until death. Covariates in Spearman, Pearson, or Mann-Whitney analyses included best-corrected VA, smoking status, macular lesions according to the Three Continent AMD Consortium classification, a modified version of the Wisconsin age-related maculopathy grading system, and age-related macular degeneration (AMD) genetic variants.
The study found that the mean area of GA at first presentation was 3.74 mm2 (95%CI, 3.11-4.67). The mean enlargement rate per year varied widely, with a mean rate of 1.09mm2 (95%CI, 0.89-1.3). Also, there was a correlation between the stage of AMD in the other eye and GA enlargement (P =.01). In 37.4% of eyes, foveal involvement was already present in incident GA, and 55% developed foveal GA after a mean period of 5.6 years. Of the 171 patients with GA, 121 (70.8%) died after a mean period of 6.4 years (SD = 5.4 years), and in 47 patients (43.9%), visual function was impaired (worse than than 20/63) at the last visit before death.
The researchers note that their findings on the relationship between GA and loss of VA correspond with those of Chakravarthy et. al, who observed a VA worse than 20/400 in 7.1% of patients with bilateral GA and 71.1% with a VA worse than 20/40 at first presentation in clinic.
“Although our examinations at 5-year intervals enabled only a rough estimate of the proportion of participants with GA who became blind before death, we observed that a high proportion of eyes with GA (66.3%) were severely visually impaired or blind before death; 49% of patients had bilateral low vision and 7% were blind,” the study explains.
Study strengths include its long follow-up time, which allowed researchers to view GA in the context of life expectancy, and its usage of all available imaging to measure GA. Limitations included the low overall number of patients with incidence GA, as well as the long period between visits.
Colijn J, Liefers B, Joachim N, et al; for the EyeNED Reading Center and EYE-RISK Consortium. Enlargement of geographic atrophy from first diagnosis to end of life. JAMA Ophthalmol. Published online May 20, 2021. doi:10.1001/jamaophthalmol.2021.1407