Clinically Observable Ocular Manifestations of Axonal Transport

Abstract

This report illustrates and provides a novel explanation for post-trabeculectomy improvements in the visual field, cup disc contours, and apparent deepening of an arcuate nerve fiber layer (NFL) defect after trabeculectomy for open-angle glaucoma. These changes are all plausible manifestations of recovered axonal transport and thickening retina, previously thinned by elevated intraocular pressure (IOP). Serial pre-and post-operative clinical fundus photos in case 1(A,B) demonstrate increased prominence of an inferior temporal arcuate nerve fiber layer defect, improved cup disc ratio, and visual field following eye pressure lowering by + 50% after trabeculectomy. Case 2 (C,D) also demonstrates obvious cup disc improvement in post-operative photos with associated improvement in visual field after trabeculectomy and lowering IOP by + 30%. We suggest that elevated IOP suppresses primarily orthograde axonal transport resulting in nerve fiber layer (NFL) thinning that can recover back to normal thickness when IOP is surgically lowered by the magnitude achieved in these two examples.