Abstract
Purpose: :
To compare the changes in visual acuity, retinal thickness and retinal sensitivity assessed with fundus-related microperimetry, after a single intravitreal bevacizumab injection for the treatment of subfoveal choroidal neovascularization due to age-related macular degeneration (AMD).
Methods: :
We retrospectively evaluated visual function and morphological changes in sixteen patients (16 eyes) with neovascular AMD at baseline and 1 month following a single pars plana injection of 2.5mg/0.1ml bevacizumab (Avastin, Genentech). Evaluation consisted of a best corrected visual acuity (VA) assessed using Early Treatment Diabetic Retinopathy Study (ETDRS) charts; central 1mm retinal thickness (CRT) measured with optical coherence tomography (Stratus III OCT, Carl Zeiss Meditech, Dublin, CA); and mean sensitivity (MS) and mean defect (MD) evaluated with MP1 microperimetry (MP1, Nidek Technologies, Tokyo, Japan). For microperimetry, a 4-2 staircase strategy with Goldmann III size stimulus was used, and 40 stimulus locations covering the central 10 degrees were examined. Paired t-tests were applied to analyze changes from baseline for each outcome parameter. The correlations between changes in retinal sensitivity, visual acuity and retinal thickness were calculated using linear regression analysis.
Results: :
At 1 month follow-up, 12 of 16 eyes (75%) showed an improvement in mean VA of 16 letters (range, 4-38 letters). Mean VA in all patients increased from 41.9 ETDRS letters at baseline to 52.3 letters at 1 month (P = .04). The mean CRT decreased from 356.3 ± 105.2 µm at baseline to 256.9 ± 83.9 µm at 1 month (P = .01). A decrease was seen in 12 patients who had an average reduction in CRT of 110 µm (P = .002). There was no significant difference in mean sensitivity (0.144 dB, P = .88) or mean defect (0.233 dB, P = .79) following treatment. Only 7 of 16 patients (43.8%) demonstrated an improvement in MS (3.1 dB, P = .06) and MD (3.0 dB, P = .03). There was a strong correlation between VA and CRT at baseline (R2 = 0.445, P = .007). Following treatment, changes in VA did not correlate significantly with CRT (R2 = 0.008, P = .76) or MS (R2 = 0.01, P = .91). Changes in CRT and retinal sensitivity, however, showed a strong trend to an inverse linear relationship (R2 = 0.296, P = .054).
Conclusions: :
A single intravitreal injection of bevacizumab induced a significant increase in VA and decrease in CRT 1 month following treatment. However, there was no significant improvement in mean retinal sensitivity. Further investigation is needed to assess whether additional treatments or a longer follow-up period would result in improved retinal sensitivity.
Keywords: age-related macular degeneration • neovascularization • perimetry