Geographic atrophy (GA) is the sequelae of macular degeneration. Automated inner retinal analysis using optical coherence tomography is flawed because segmentation software is calibrated for normal eyes. The purpose of this study is to determine whether ganglion cell layer (GCL) volume is reduced in GA using manual analysis.
Nineteen eyes with subfoveal GA and 22 controls were selected for morphometric analyses. Heidelberg scanning laser ophthalmoscope optical coherence tomography images of the optic nerve and macula were obtained, and the Viewing Module was used to manually calibrate retinal layer segmentation. Retinal layer volumes in the central 3-mm and surrounding 6-mm diameter were measured. Linear mixed models were used for statistics.
The GCL volume in the central 3 mm of the macula is less (P = 0.003), and the retinal nerve fiber layer volume is more (P = 0.02) in patients with GA when compared with controls. Ganglion cell layer volume positively correlated with outer nuclear layer volume (P = 0.020).
The patients with geographic atrophy have a small significant loss of the GCL. Ganglion cell death may precede axonal loss, and increased macular retinal nerve fiber layer volumes are not indicative of GCL volume. Residual ganglion cell stimulation by interneurons may enable vision in patients with GA.
With manual segmentation of retinal layers in optical coherence tomography images, we found that the macular ganglion cell volume is significantly reduced in patients with geographic atrophy compared with healthy controls.
*Department of Ophthalmology, Jacobs Retina Center, Shiley Eye Institute, University of California, San Diego, San Diego, California; and
†University of California San Diego School of Medicine, San Diego, California.
Reprint requests: Hema L. Ramkumar, MD, Department of Ophthalmology, Jacobs Retina Center, Shiley Eye Institute, University of California, San Diego, 9415 Campus Point Drive, La Jolla, San Diego, CA 92093-0946; e-mail: firstname.lastname@example.org
Supported in part by UCSD Vision Research Center Core Grant P30EY022589 (W. R. Freeman), NIH Grant EY016323 (D.-U. Bartsch), and an unrestricted grant from Research to Prevent Blindness, NY (W. R. Freeman).
None of the authors has any conflicting interests to disclose.