A retrospective longitudinal study of 52 Finnish patients with X-linked retinoschisis

Purpose: To describe clinical characteristics in Finnish patients with X-linked retinoschisis (XLRS) longitudinally with emphasis on retinal morphology and genotype-phenotype correlations. Methods: A retrospective cohort study reviewed medical records from patients with genetically confirmed XLRS from the Department of Ophthalmology, Helsinki University Hospital. Best-corrected visual acuity (BCVA), refraction, colour fundus photography, spectral-domain optical coherence tomography and genetic information were collected. Results: Fifty-two males were diagnosed at the median age of 7 years (range 1-57) and followed for a median of 8 years (range, 1-49). Baseline findings included macular retinoschisis in 92 (89%), macular atrophy in 25 (24%) and peripheral retinoschisis in 22 (21%) eyes. Vitreous haemorrhage occurred in 10 (10%) eyes, more frequently with peripheral schisis (p < 0.001). Nearly half of the patients, 22 (42%) were classified as visually impaired according to WHO. Median central retinal thickness was similar between initial (355 mu m) and latest visits (360 mu m) (p = 0.781). Low BCVA was associated with macular atrophy (p < 0.001), ellipsoid zone disruption (p = 0.007) and peripheral retinoschisis (p = 0.006). The three Finnish founder mutations c.214G >A, c.221G >T, and c.325G >C in exon 4 of retinoschisin 1 (RS1) were identified in 40 patients (77%). No associations were found between the genotypes and phenotypes. Conclusion: Three-fourths of the patients carried the Finnish founder mutations in RS1, but we did not detect any genotype-phenotype association. Macular atrophy was associated with the poorest visual acuity. Ocular compilations were associated with peripheral retinoschisis, suggesting that these patients should be followed more frequently.