Purpose: To examine the microstructural changes in the inner nuclear layer (INL) and ganglion cell layer (GCL) in a primary open-angle glaucoma (POAG) subject at 2 timepoints, 4 months apart.
Patients and methods: This case-control study (1 POAG subject and 1 normal control) used the single cell, 3-dimensional volumetric imaging capability of an adaptive optics-optical coherence tomography-scanning laser ophthalmoscopy system to examine the inner retina.
Results: At the area of greatest glaucomatous change in the POAG subject [3-degrees temporal (T), 3-degrees inferior (I), right eye], the GCL was greatly thinned at both timepoints, yet retinal ganglion cell soma remained visible amid a meshwork of capillaries. Microcystic lesions in the INL were visible at both timepoints, ranging in diameter from 8 to 43 μm on day 1 to 11 to 64 μm at 4 months, with an average diameter increase of ∼124%. Small hyperreflective features (not seen in the contralateral eye or control subject) at a depth midway through the INL seemed correlated to the development of microcysts.
Conclusions: We demonstrate the ability to image microcystic lesions early in their development and have quantified longitudinal changes. The presence of small hyperreflective structures at a layer midway through the INL seems to be a precursor to their formation and is a potential biomarker for assessing POAG severity and progression. The adaptive optics imaging system is also able to visualize retinal ganglion cells in this subject, despite severe thinning of the GCL.