Purpose: One approach for restoring vision in end-stage hereditary retinal diseases is implantation of a subretinal microphotodiode array. We analyzed retinal fluorescein angiography findings of the implant area.
Methods: In this pilot study, patients (n = 11; 10 men, one woman; ages 45.2 ± 8.7 years), with visual acuity of light perception or worse resulting from a hereditary retinal degenerative disease, received active electronic subretinal visual implants. Implants were removed after 4 weeks (n = 7 subjects) or 4 months (n = 4 subjects). Following implantation, regular fluorescein angiography was performed. Regions of retinal capillary loss, microaneurysms, capillary alterations, neovascularization and leakage over the implant were scored at time points T1 (days 1-14), T2 (days 15-28) and T3 (months 3-4). Occurrence and changes of fluorescein angiographic phenomena are reported.
Results: In terms of the number of patients in whom retinal alterations were observed (compared to available images) the occurences of the angiographic phenomena (for time points T1, T2 and T3, respectively) were as follows: regions of capillary loss (five of seven, 10 of 11 and five of five patients), microaneurysms (0 of seven, two of 11 and three of five patients), calibre alterations of the capillaries (three of seven, eight of 11 and five of five patients), retinal neovascularization (one of seven, one of 11 and 0 of five) and leakage (three of seven, seven of 11 and four of five). The Friedman test revealed no significant changes in capillary loss, calibre alteration of the capillaries, neovascularization or leakage. Microaneurysms increased significantly (p = 0.037).
Conclusions: Subretinal visual implants lead to increased capillary microaneurysms, a possible compensatory mechanism following recovery of inner retinal activity. There were no significant changes in capillary loss, calibre alteration of the capillaries, retinal neovascularization and leakage at 4 months. Further study will determine whether and to what degree long-term vascular changes are affected by the surgical procedure, the implant itself and/or recovery of retinal neuronal activity.