gms | German Medical Science

Objective: Topographic analysis of structural and functional changes in the natural history of geographic atrophy (GA) based on multimodal imaging, ETDRS charts and psychophysical microperimetry assessment.

Methods: Retrospective analyses of datasets from the research centre Internationale Innovative Ophthalmochirurgie (I.I.O.), Düsseldorf, Germany, from 2015 to 2021 were performed. Eyes of patients with GA fulfilling the inclusion criteria from phase 3 study OAKS were classified as study eyes (SEs). Available data points were assessed at time of first visit as well as after 12, 24, 36, 48 and 60 months (5 years) for measurement of best-corrected visual acuity (ETDRS charts) and multimodal imaging including spectral domain optical coherence tomography (SD-OCT Cirrus; Carl Zeiss). Additionally, macular functional assessment via microperimetry (MAIA; CenterVue) was performed to measure light threshold sensitivity changes and presence of absolute scotoma differentiated by individual foveal regions. Missing measurement timepoints were imputed via linear mixed models. Areas of both atrophy and scotoma as well as their longitudinal development were analyzed.

Results: Overall 13 patients (57–82 years of age; median: 69.7 years) with 20 SEs were included into the study. Over a five-year observation period, the proportion of SEs with no visual impairment [≥70 ETDRS letters] was reduced from 55.0% to 30.0%, whereas the proportion of SEs with moderate or more severe visual impairment [<60 ETDRS letters] increased from 20.0% to 55.0%. The average macular sensitivity worsened from 15.7 dB (95%-CI [12.6 dB, 18.9 dB]) to 7.4 dB (95%-CI [4.1 dB, 10.7 dB]). The proportion of absolute scotoma increased from 15.7% to 43.5% as measured across all stimulus points. Upon occurrence of absolute scotoma in the fovea centralis and/or subfoveal center, the proportion of SEs with no visual impairment [≥70 ETDRS letters] dropped from 72.7% prior to subfoveal encroachment to 7.1% one year after subfoveal encroachment. In contrast, the proportion of SEs with moderate visual impairment or worse [<60 ETDRS letters] increased from 18.2% prior to subfoveal encroachment to 57.1% one year after subfoveal encroachment.

Summary: During natural history of GA, substantial deterioration of macular outcomes and visual functionality was detected. The occurrence of absolute scotoma as identified via psychophysical measures of microperimetry was associated with an evident worsening in terms of visual impairment levels.