Abstract
Purpose :
Macular schisis is commonly observed in individuals with X-linked retinoschisis (XLRS) and enhanced S-cone syndrome (ESCS). The schisis can occur in several retinal layers in XLRS, perhaps most commonly in the inner nuclear layer (INL), whereas the schisis location in ESCS is less documented. The present study quantified retinal layer thickness as an approach to infer the location of macular schisis in XLRS and ESCS.
Methods :
Horizontal macular B-scans (9 mm width) were acquired from 22 control subjects (25 to 50 yo, 14 males), 9 subjects with XLRS (18 to 50 yo; all genetically confirmed), and 6 subjects with ESCS (16 to 48 yo; 3 males; 5 genetically confirmed). The thickness of the INL, outer nuclear layer plus outer plexiform layer (OPL+ONL), and outer segments of the photoreceptors (OS+) was calculated from the scans using a semi-automated approach. For each layer, thickness was averaged throughout the scan and ANOVA on ranks was used to compare mean thickness for the three subject groups.
Results :
Eight of 9 XLRS subjects and 5 of 6 ESCS subjects had macular schisis by OCT imaging. The INL was abnormally thick for all XLRS subjects, and ranged from normal to abnormally thin for all but one ESCS subject. As a group, the INL was significantly thicker than normal for the XLRS subjects (Q = 3.85, p < 0.05), but not significantly different from normal for the ESCS subjects (Q = 1.75, p > 0.05). Conversely, the OPL+ONL was abnormally thick for all ESCS subjects and abnormally thin for all XLRS subjects. The mean OPL+ONL was significantly thicker than normal for the ESCS subjects (Q = 3.62, p < 0.05) and significantly thinner than normal for the XLRS subjects (Q = 2.81, p < 0.05). The OS+ was abnormally thin for all but one XLRS subject, and ranged from borderline-thin to thick for the ESCS subjects. As a group, the OS+ was significantly thinner than normal for the XLRS subjects (Q = 3.85, p < 0.05), but not significantly different from normal for the ESCS subjects (Q = 0.16, p > 0.05).
Conclusions :
In this sample of subjects, macular schisis was predominately located in the INL of XLRS subjects and in the OPL+ONL of ESCS subjects. Additionally, photoreceptor thinning appears to be a common characteristic of XLRS that is less apparent in ESCS. These data may provide an additional objective approach to differentiate between XLRS and ESCS.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.