Abstract
Purpose :
Geographic atrophy (GA) is a devastating development in patients with dry age-related macular degeneration, and histopathologic studies reported ganglion cell death in these patients. This study will determine if ganglion cell death in GA can be observed with optical coherence tomography (OCT).
Methods :
Six eyes with subfoveal GA and seven age- matched controls were selected for morphometric analyses. Heidelberg scanning laser ophthalmoscope OCT images were obtained, and the Spectralis viewing module software was used with manual calibration to ensure appropriate segmentation. The retinal nerve fiber layer, ganglion cell layer, and outer nuclear layer volumes were measured in the central 1 mm and superior, inferior, nasal, and temporal regions including a 3 mm diameter around the fovea. A two-tailed student’s t-test was used for statistical analyses.
Results :
The outer nuclear layer volume is significantly less (0.41 ± 0.03 mm3) in GA patients when compared with controls (0.50 ± 0.01 mm3), p=0.022. The ganglion cell layer volume is significantly less (0.22 ± 0.02 mm3) in GA patients when compared with controls (0.30 ± 0.01 mm3), p=0.003. There is no significant difference in the retinal nerve fiber layer volume in GA patients compared with controls. There is a significant positive correlation between outer nuclear layer and ganglion cell volume r(11)= 0.64, p=0.018.
Conclusions :
Our results are consistent with histopathologic studies that demonstrate transsynaptic degeneration of the ganglion cells in patients with GA. This study demonstrates that measuring the ganglion cell layer with manual segmentation is possible from OCT images in GA patients. Despite the small decrease in outer nuclear layer volume, there is significant associated ganglion cell volume loss. With multiple potential therapies for geographic atrophy on the horizon, evaluation of the ganglion cell layer may be important for determining visual potential.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.