Purpose:
To assess the utility of low luminance acuity deficit (LLD) as a predictor of disease progression in eyes with geographic atrophy (GA) secondary to age-related macular degeneration (AMD).
Methods:
Two cohorts of dry AMD patients were enrolled in the COMPLement Inhibition with Eculizumab for the Treatment of Non-Exudative Age-Related Macular Degeneration (COMPLETE) Study. Cohort-1 was comprised of eyes with drusen in the absence of GA, and the drusen had a volume of at least 0.03 mm3 within a 3 mm diameter circle centered on the fovea based on SDOCT imaging. Cohort-2 was comprised of eyes with GA measuring from 1.25 mm2 to 18 mm2 based on SDOCT fundus imaging. Ophthalmologic exams, normal and low luminance ETDRS visual acuity testing, and imaging studies were performed at baseline and at follow-up months 3, 6, 9, and 12. Imaging studies included color and AF imaging with a fundus camera based flash system (TRC-50DX, Topcon Medical Systems), AF and FA imaging with a confocal SLO system (Spectralis, Heidelberg Engineering), and SDOCT imaging (Cirrus, Carl Zeiss Meditec Inc.). Low-luminance acuity (LLA) was measured by placing a 2.0-log unit neutral density filter (Kodak Wratten filter; Kodak) over the eye in which acuity was being measured and having the participant read the normally illuminated ETDRS chart. LLD was defined as the number of ETDRS letters read without the neutral density filter (NLA) minus LLA. Statistical analysis was performed using Pearson correlations.
Results:
A total of 30 GA patients (Cohort-2) were enrolled in the study. Only one eye of each patient was included as a study eye, although 19 fellow eyes, which met entry criteria, were evaluated as a secondary endpoint. At baseline, an average of 66.4 (15.7) letters were read at normal luminance while 45.0 (16.4) letters were read at low luminance for a LLD of 21.4 (11.5) letters. The average distance from the edge of the GA lesion to the foveal center was 0.12 (0.18) mm. At baseline, distance to the foveal center was correlated with both NLA (p=0.001, r=0.46) and LLA (p=0.05, r=0.28), but not LLD (p=0.11, r=0.23). LLD was not correlated with SDOCT measurements of GA area (p=0.77, r=-0.04). The correlations between LLD and growth rates are currently being analyzed.
Conclusions:
At baseline, LLD did not correlate with the distance of the lesion edge to the foveal center or lesion size. Whether it is predictive of disease progression remains to be determined.
Clinical Trial:
http://www.clinicaltrials.gov NCT00935883
Keywords: age-related macular degeneration • visual acuity • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials