Evaluation of a calculation model to estimate the impact of the COVID-19 pandemic lockdown on visual acuity in neovascular AMD

Purpose A model was calculated during the first Austrian coronavirus disease-2019 (COVID-19) pandemic lockdown to estimate the effect of a short-term treatment interruption due to healthcare restrictions on visual acuity (VA) in neovascular age-related macular degeneration (nAMD). The model was compared to the real-life outcomes before treatment re-started. Methods Retrospective data-collection of 142 eyes in 142 patients receiving repeated intravitreal injections with anti-VEGF at a retina unit in Vienna in a personalized pro-re-nata regimen prior to the COVID-19 associated lockdown, when treatment was deferred between March 16 and May 4, 2020. During the lockdown, the preliminary data was integrated into pre-existing formulae based on the natural course of the disease in untreated eyes in the long term. Patients were re-scheduled and treated after gradually opening operating rooms. The calculation model was compared to the effective VA change. Results The model calculated an overall VA loss of 3.5 +/- 0.8 letters early treatment diabetes retinopathy study (ETDRS) (p < 0.001 [95% CI:3.3;3.6]) on average compared to 2.5 +/- 6 letters ETDRS (p < 0.001 [95% CI:1.5;3.5]) as measured with a mean treatment delay of 61 +/- 14 days after previously scheduled appointments. The total difference between the model exercise and the real-life outcomes accounted for 1 +/- 5.9 letters ETDRS (p = 0.051 [95% CI: 0.1;1.9]). Conclusion The herein presented calculation model might not be suitable to estimate the effective VA loss correctly over time, although untreated eyes and eyes under therapy show similarities after short-term treatment interruption. However, this study demonstrated the potentially negative impact of the COVID-19 pandemic lockdown on patients compromised by nAMD.