Multifocal Pupillography Identifies Ranibizumab-Induced Changes in Retinal Function for Exudative Age-Related Macular Degeneration

Abstract

To investigate the efficacy of multifocal pupillographic objective perimetry (mfPOP) to quantify the effects of intravitreal ranibizumab injection for choroidal neovascularization (CNV) secondary to exudative age-related macular degeneration (AMD). mfPOP visual fields from 20 patients with unilateral exudative AMD treated with intravitreal ranibizumab were measured before and after 3 months of treatment and were compared with that in 30 normal subjects. Two stimulus types consisting of ensembles of 24 or 44 independent stimuli per eye had a mean presentation interval at each region of 1 second. Pupil responses were recorded with video cameras under infrared illumination. Multiple linear models were fitted to contraction amplitudes and delay to peak responses, to determine the independent effects of exudative AMD before and after ranibizumab therapy. After 3 months of treatment, mean additional response delays compared to normal subjects for the 24-region stimulus improved significantly (P < 5 × 10⁻⁹) from a mean of 18.82 ± 3.0 ms at baseline to 7.45 ± 3.15 ms. The mean effect of exudative AMD at baseline decreased constriction amplitude by -1.11 ± 0.24 dB (P < 0.00001) with little improvement after ranibizumab therapy. Small pretreatment elevations of extrafoveal sensitivity correlated with improvements in central retinal thickness (CRT) after treatment (P < 0.0005). Improvements in mfPOP contraction amplitudes and time to peak responses were measured in eyes treated with intravitreal ranibizumab; however, response delays appeared to be the most indicative of functional improvement. Confirmation of hypersensitivity in the extrafoveal field in a larger group may support this finding as a prognostic marker for good treatment outcomes.