Unexplained visual loss after gas tamponade for macula-on retinal detachment: incidence and clinical characterization.

Purpose To identify the incidence rate and the clinical characteristics of unexplained visual loss after gas tamponade for primary macula-sparing rhegmatogenous retinal detachment (RRD). Methods Retrospective longitudinal analysis of all subjects undergoing vitrectomy with gas for primary macula-on RRD from 2010 to 2019. Outcome was the unexplained visual loss evaluated after gas absorption, defined as a loss of vision to less than 20/200 without evident causes. The diagnostic work-up was reviewed. Results Nine eyes with unexplained visual loss out of 357 surgeries were found. The incidence proportion was 2.52 new cases every 1000 eyes affected by macula-on RRD treated with gas per year. All subjects had an absolute central scotoma, with a median post-operative visual acuity of 20/1600 (counting fingers). Structural findings were consistent with an axonal damage: all eyes had microcystoid macular edema and reduced thickness of both macular ganglion cell and retinal nerve fiber layers. No photoreceptor structural damages were noted. Conclusions The incidence of unexplained visual loss after gas tamponade for primary macula-on RRD is 2.52 new cases every 1000 eyes per year. This rare complication, which findings are suggestive of an axonal damage within retinal ganglion cells, remains a serious and unexplained concern for vitreoretinal surgeons.