Multimodal analysis of the Preferred Retinal Location and the Transition Zone in patients with Stargardt Disease

Purpose: The purpose of our study was to investigate morpho-functional features of the preferred retinal location (PRL) and the transition zone (TZ) in a series of patients with recessive Stargardt disease (STGD1). Methods: Fifty-two STGD1 patients with at least one ABCA4 mutation, atrophy of the central macula (MA) and an eccentric PRL were recruited for the study. Microperimetry, fundus autofluorescence (FAF), spectral-domain optical coherence tomography (SD-OCT) were performed. The location and stability of the PRL along with the associated FAF pattern and visual sensitivities were determined and compared to the underlying retinal structure. Results: The mean visual sensitivity of the PRLs for the 52 eyes was 10.76 +/- 3.70 dB. For the majority of eyes, PRLs were associated with intact ellipsoid zone (EZ) bands and qualitatively normal FAF patterns. In 17 eyes (32.7%) the eccentric PRL was located at the edge of the MA. In 35 eyes (67.3%) it was located at varying distances from the border of the MA with a TZ between the PRL and the MA. The TZ was associated with decreased sensitivity values (5.92 +/- 4.69 dB) compared to PRLs (p<0.05), with absence/disruption of the EZ band and abnormal FAF patterns (hyper or hypo-autofluorescence). Conclusions: In STGD1 eccentric PRLs are located away from the border of MA and associated with intact EZ bands and normal FAF. The TZ is characterized by structural and functional abnormalities. The results of multimodal imaging of the PRL and TZ suggest a possible sequence of retinal and functional changes with disease progression that may help in the planning of future therapies; RPE dysfunction appears to be the primary event leading to photoreceptor degeneration and then to RPE loss.