Structure/psychophysical relationships in X-linked retinoschisis

Purpose. To compare structural properties from spectral-domain optical coherence tomography (SDOCT) and psychophysical measures from a subset of patients enrolled in a larger multicenter natural history study of X-linked retinoschisis (XLRS). Methods. A subset of males (n = 24) participating in a larger natural history study of XLRS underwent high-resolution SDOCT. Total retina (TR) thickness and outer segment (OS) thickness were measured manually. Shape discrimination hyperacuity (SDH) and contour integration perimetry (CIP) were performed on an iPad with the myVisionTrack application. Sensitivity was measured with fundus-guided perimetry (4-2 threshold testing strategy; 10-2 grid, spot size 3, 68 points). Correlation was determined with Pearson’s r correlation. Values are presented as the mean ± SD. Results. Mean macular OS thickness was less in XLRS patients (17.2 ± 8.1 μm) than in controls (37.1 ± 5.7 μm; P < 0.0001) but mean TR thickness was comparable (P = 0.5884). For patients, total sensitivity was lower (13.2 ± 6.6 dB) than for controls (24.2 ± 2.4 dB; P = 0.0008) and had a strong correlation with photoreceptor OS (R² = 0.55, P = 0.0001) and a weak correlation with TR thickness (R² = 0.22, P = 0.0158). The XLRS subjects had a logMAR best corrected visual acuity (BCVA) of 0.5 ± 0.3 that was associated with OS (R² = 0.79, P < 0.0001) but not TR thickness (R² = 0.01, P = 0.6166). Shape DH and CIP inner ring correlated with OS (R² = 0.33, P = 0.0085 and R² = 0.47, P = 0.0001, respectively) but not TR thickness (R² = 0.0004, P = 0.93; R² = 0.0043, P = 0.75, respectively). Conclusions. When considered from a single visit, OS thickness within the macula is more closely associated with macular function than TR thickness within the macula in patients with XLRS.