Effect of intraocular pressure lowering on the capillary density of optic nerve head and retinal nerve fiber layer in patients with glaucoma

Purpose: To evaluate the effect of IOP lowering on the capillary density of optic nerve head and retinal nerve fiber layer in patients with primary open angle glaucoma. Methods: Twenty eyes of 14 glaucomatous patients and 15 eyes of nine normal patients were enrolled. The most appropriate hypotonic treatment was applied to every patient. A HD Angio Disc 4.5 scan (Avanti-AngioVue) was performed at baseline and after a month in the glaucomatous eyes. The following parameters were analyzed: Radial Papillary Capillaries (RPC) density, inside disc, peripapillary, superior-hemi, inferior-hemi, quadrants, and peripapillary, hemi-superior, hemi-inferior, and quadrants RNFL thickness. Optic nerve head analysis was also evaluated. In addition, the RPC density and the RNFL were assessed in the eight sectors provided by the software. Results: The RPC density did not significantly change after IOP reduction ( p > 0.05). The inferior-temporal ( p = 0.005) and inferior-nasal sectors ( p < 0.001) showed a greater capillary density than the respective superior sectors in healthy eyes. In contrast in the glaucomatous eyes, the superior-nasal exhibited greater capillary density with respect to the inferior-nasal sectors. The aggregate RPC density of the inferior sectors was greater than the superior ones in the control group ( p < 0.001). An improvement of the average disc area ( p = 0.01) and the average cup volume ( p = 0.059) were also observed along with increased RNFL thickness at different locations (all, p < 0.05) after IOP lowering therapy was initiated. Conclusion: The glaucomatous eyes presented rarefaction of the radial papillary capillaries density in the inferior sectors, but no significant changes in the density after IOP-lowering medications.