BASICS
DESCRIPTION
X-linked retinoschisis is a genetic disorder of the retina that primarily affects males in the 1st decade leading to decreased vision, foveal schisis, and peripheral retinoschisis in both eyes.
EPIDEMIOLOGY
Prevalence
It is an uncommon disease that has been described in multiple countries, with the highest carrier prevalence reported in Finland: 14 per 10,000 people (1)[A].
RISK FACTORS
Genetics
X-linked recessive disorder with full penetrance
PATHOPHYSIOLOGY
Gene mutations that encode retinoschisis (RS1) cause this disease (2).
ETIOLOGY
• A primary defect in the Müller cell has been proposed as the etiology of this disease process.
• An abnormality of retinal and choroidal vascular development has also been proposed to cause the retinoschisis cavities.
DIAGNOSIS
HISTORY
• X-linked retinoschisis occurs almost exclusively in males who typically present in the first decade of life with decreased vision, strabismus, and nystagmus.
• It may present as early as infancy with nystagmus.
PHYSICAL EXAM
• Foveal retinoschisis is the most characteristic ophthalmoscopic finding and is present in virtually all patients. Radiating striae in the internal limiting membrane (ILM) and foveal microcysts are typically seen. In older patients, pigmentary changes and retina pigment epithelial (RPE) atrophy often evolve over time.
• In approximately 50% of patients, peripheral retinoschisis is present, often inferotemporally. The splitting typically affects the superficial retinal layers.
• Vascular changes such as sheathing, microvascular abnormalities, and retinal neovascularization are sometimes seen.
• Up to 29% of patients have hyperopia and/or strabismus.
• Vitreous hemorrhage and retinal detachment are complications of X-linked retinoschisis. Vitreous hemorrhage can occur from rupture of poorly supported retinal blood vessels or less frequently from neovascularization.
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• The electroretinogram (ERG) shows reduced b-wave amplitude in all patients. The a-wave is initially normal but may be reduced in older patients. In advanced cases, the ERG can be virtually unrecordable.
• Visual field testing generally demonstrates a relative central scotoma and absolute scotomas corresponding to the peripheral schisis cavities.
Imaging
Optical coherence tomography (OCT) can be performed to further assess the foveomacular schisis changes. Although X-linked retinoschisis has traditionally been associated with nerve fiber layer schisis, one study indicates that the schisis cavities can affect multiple layers (nerve fiber layer, inner nuclear layer, outer nuclear layer/outer plexiform layer) and the entire macula (3)[A].
DIFFERENTIAL DIAGNOSIS
• Acquired retinoschisis
• Retinitis pigmentosa
• Retinal vasculitis
• Goldmann–Favre syndrome: Foveal schisis is also seen. However, the inheritance pattern is autosomal recessive. Patients typically have severe nyctalopia and reduced a- and b-waves on ERG.
TREATMENT
MEDICATION
• There is no cure for this disorder.
• Refractive error, strabismus, and amblyopia should be treated appropriately.
• Prophylactic laser photocoagulation treatment of schisis cavities has been associated with an increased incidence of rhegmatogenous retinal detachment and, therefore, is not recommended.
• Repair of retinal detachments with vitrectomy and internal tamponade has shown the best results (4). Repair with scleral buckling has had variable outcomes.
• Panretinal photocoagulation is effective in managing neovascularization.
• Vitreous hemorrhage typically clears spontaneously. In cases of dense or nonclearing hemorrhages, vitrectomy may be considered, and should be performed earlier in the amblyogenic age groups.
• Some case reports have suggested a benefit of topical dorzolamide in the treatment of foveal cystic-appearing lesions with improvement in visual acuity (5)[A].
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
• This is a chronic, slowly progressive disorder.
• Patients should be followed regularly to monitor for complications.
PATIENT EDUCATION
All affected patients and their families should undergo genetic counseling.
PROGNOSIS
Vision loss progresses slowly with retention of reasonable vision until the 5th or 6th decade when visual acuity may worsen secondary to macular atrophy.
COMPLICATIONS
Up to 20% of patients will develop retinal detachment, and up to 40% will develop vitreous hemorrhage.
REFERENCES
1. George ND, Yates JR, Moore AT. X linked retinoschisis. Br J Ophthalmol 1995;79:697–702.
2. Sergeev YV, Caruso RC, Meltzer MR, et al. Molecular modeling of retinoschisin with functional analysis of pathogenic mutations from human x-linked retinoschisis. Hum Mol Genet 2010;19(7):1302–1313.
3. Yu J, Ni Y, Keane PA, et al. Foveomacular schisis in juvenile X-linked retinoschisis: An optical coherence tomography study. Am J Ophthalmol 2010;149(6):973–978.
4. Garg SJ, Lee HC, Grand MG. Bilateral macular detachments in X-linked retinoschisis. Arch Ophthalmol 2006;124(7):1053–1055.
5. Apushikin MA, Fishman GA. Use of dorzolamide for patients with X-linked retinoschisis. Retina 2006;26:741–745.
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