Caracterização do Edema Macular Cistóide na Retinopatia Pigmentar com Recurso a Tomografia de Coerência Óptica Swept-Source

INTRODUCTION: Retinitis pigmentosa (RP) may be complicated by cystoid macular edema (CME), which contributes to central vision loss. The underlying pathophysiology of RP-associated CME (RP-CME) and its impact in prognosis remains uncertain. Our objective was to investigate the association between cystoid spaces (CS), retinal morphometric parameters and clinical data in RP-CME using swept-source optical coherence tomography (SS-OCT). METHODS: Prospective study conducted at an IRD referral center in Portugal. Consecutive RP patients with evidence of CME were recruited from the Retinal Dystrophies Clinic and invited to undergo SS-OCT (Zeiss PLEX Elite 9000). Morphometric assessment using the in-built software was performed by 2 independent graders (CC and CN) and included: central point outer nuclear layer thickness (CPONLT), ellipsoid zone area (EZA), central macular thickness (CMT), CS location (central point, central millimeter, outside central millimeter), CS retinal layer involvement and CS size. Clinical data, such as gender, age, genetic variants, best-corrected visual acuity (BCVA), lens status and vitreomacular interface status were registered. RESULTS: We enrolled 40 eyes from 21 patients (71.5% male; mean age 47.3±15.2 years). In 61.90% the inheritance pattern was autosomal recessive, 80.95% had non-syndromic disease and 90.48% had bilateral CME. Mean BCVA was 68.06±14.55 ETDRS letters. CS were found in the inner nuclear layer in 100% of eyes and in the outer nuclear layer in 50%. CS involved the central point or central millimeter in 85% eyes (17 eyes each); 6 cases (15%) showed CS outside central millimeter. Size and retinal layer involvement were not associated with BCVA (p=0.548 and p=0.285). CS in the central point were associated with higher EZA when compared to those without central point involvement (p=0.009). EZA and CPONLT correlated with BCVA (r=0.351, p=0.0286 and r=0.387, p=0.0462). CONCLUSION: CS involving the central point were associated with higher EZA values, showing that central point involvement happens in less severe disease stages with more preserved visual function. The correlation between CPONLT and BCVA highlights the importance of this outer retinal layer for visual function in RP-CME. Further studies are needed to obtain a profound understanding of this entity along with the true impact of CS in visual function.