Objective: To evaluate long-term changes in visual acuity, clinical features and complications in X-linked retinoschisis, and to analyse recombinant chromosomes in affected males, carrier females and unaffected males to further refine the retinoschisis gene locus.
Design: Longitudinal study.
Setting: Ophthalmology department at a university-affiliated hospital in Saskatoon.
Patients: A total of 92 male patients from 6 pedigrees affected with X-linked retinoschisis examined between 1962 and 1994. Of the 92, 73 were followed for a mean of 19.78 (standard deviation 8.74) years (range 1.5 to 31 years). Blood samples were taken from 91 affected males, 100 unaffected males and 86 carrier females for DNA analysis.
Outcome measures: Significant visual loss was defined as a doubling or more in the visual angle. Clinical comparisons of fundus features were aided by stereoscopic fundus photographs.
Results: The mean geometric visual acuity was 20/67 on initial examination and 20/78 on last assessment. Significant loss in visual acuity occurred in 18 (21.2%) of 85 eyes of 43 patients during childhood or adolescence and in 20 (17.1%) of 117 eyes of 59 patients in the postadolescent period. All 183 eyes had changes at the macula. Peripheral schisis was detected in 106 eyes (57.9%), with a mean of 1.48 (standard deviation 1.03) involved quadrants. Asymmetric disease was detected in 19 patients (20.6%). Vitreal hemorrhages occurred in 24 eyes (13.1%), retinal detachments in 10 (5.5%). Thirteen eyes (7.1%) of eight patients had a very poor visual outcome (light perception or no light perception). A new gene, XLRSI, was identified by means of positional cloning. XLRSI is mutated in affected people.
Conclusions: In uncomplicated cases of X-linked retinoschisis the visual prognosis is good. There is wide variation in clinical features among those affected and in the disease over time.