Time-dependent effects on contrast sensitivity, near and distance acuity: difference in functional parameters? (Prospective, randomized pilot trial of photodynamic therapy versus full macular translocation)

Abstract

To report the change of contrast sensitivity (CS) after photodynamic therapy (PDT) vs full macular translocation (FMT) for neovascular age-related macular degeneration (AMD), and to relate this to other measures of visual function (distance and near acuity). Fifty patients (50 eyes) with predominantly classic subfoveal choroidal neovascularisation (CNV) secondary to AMD were randomized to PDT or FMT. CS was measured with Pelli-Robson charts. Acuity scores of near visual function (NVS) were calculated after testing with visual acuity cards of the Swiss National Association of and for the Blind (SNAB). Best corrected distance visual acuity (DVA) was determined according to a standardized protocol with EDTRS charts. Primary end point was the change of CS at 12-month examination from baseline. The interaction of the CS with NVS and DVA was analysed. Mean CS showed a decrease in both treatment groups (FMT: -2 letters, PDT: -3 letters, p=0.969) at 12-month examination from baseline. While mean NVS improved by seven letters in the FMT group, a decrease of more than ten letters was seen in the PDT group (p<0.05). We found no agreement between CS and high-contrast acuity (NVS, DVA). In FMT patients, the parameters at baseline (CS, NVS, DVA) correlated poorly with the corresponding 12-month results, therefore providing no informative basis to predict the later functional development. In contrast, PDT patients showed strong baseline-to-outcome coherence with baseline measures also associated with better final values. Although FMT can initiate recovery of near and distance acuity over the period of 1 year in selected patients with classic CNV, CS did not differ between FMT and PDT. We found no close connection of CS with DVA or NVS, especially after FMT. Knowledge about the unequal variation of visual parameters can provide more comprehensive information when advising patients on different therapeutic options. That also applies in particular to vascular endothelial growth factor inhibitors, which seem to promise an even higher extent of gain in CS and to reach the peak of recovery at an earlier time.