Abstract
Purpose: :
To report the full-field electroretinography (ffERG) results and assess retinal function in neovascular age-related macular degeneration (nAMD) patients treated with intravitreal ranibizumab during 6 months.
Methods: :
Twenty-four eyes of 24 treatment-naive patients with nAMD received 3 loading dose injections with 0.5 mg ranibizumab with 4 weeks intervals and were treated on an as- needed basis thereafter. Full-field ERG recordings were performed using a Ganzfeld stimulator (Visual-Evoked Response Imaging System). Stimulus intensities recorded after 30 minutes of dark adaptation were rod ERG with single flash dim white -2.5 log, combined rod-cone ERG with single flash white 0.5 log, 2.0 log and 3.0 log. Isolated cone responses were obtained after 10 minutes of light adaptation using single-white flash and 30-Hz white flicker stimulus. Mean a- and b-wave amplitudes and implicit times were analyzed. Three and 6 months results were compared to baseline. ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity (VA) was also evaluated. Paired t-test/Wilcoxon Signed Rank Test was used for statistical analysis.
Results: :
The rod ERG showed significant improvement in b-wave amplitude at 6 months and in implicit times at 3 and 6 months (p<0.05). The b-wave amplitude of the combined rod-cone responses 2.0 and 3.0 log significantly decreased at 6 months and the b-wave implicit time of the single flash cone response was significantly increased (p<0.05). Furthermore, 30-Hz flicker implicit times significantly increased compared to baseline. Mean VA improved significantly from a baseline of 58.3 letters to 62.4 letters at 3 months (p=0.027). At 6 months VA returned to baseline level with a mean of 57.3 letters. Mean number of injections was 3.9 (range 3 to 6).
Conclusions: :
Full-field ERG results indicate alterations in retinal function during 6 months follow-up of ranibizumab treated nAMD patients. The isolated rod function showed improvement however, the analyses of the combined rod-cone and especially the isolated cone responses might indicate a decreased cone function after 6 months compared to baseline.
Keywords: electroretinography: clinical • age-related macular degeneration