cystic degeneration

Retinoschisis, Juvenile

Clinical Characteristics
Ocular Features: 

Retinoschisis is a retinal disorder characterized by a cystic degeneration of the retina, leading to a split of retinal layers mainly at the level of the nerve fiber layer. Almost all patients have macular involvement, most commonly with foveal spoke-like streaks consisting of microcystic cavities that may coalesce over time. Retinal pigment epithelium atrophy and pigment clumping may occur.  Peripheral schisis is evident in about 50% of patients with large bullous cavities that may resolve spontaneously leaving a pigmented demarcation line. Other retinal findings are white retinal flecks, exudative retinopathy with retinal detachment, perivascular sheathing and dendritiform vessels in the periphery. Vitreous veils are commonly seen that are caused by separation of the thin inner wall of a peripheral schisis cavity and inner wall holes. Bridging vessels may rupture into the cystic cavity or the vitreous. The onset of the disorder has been detected as early as three months, but the majority of cases are five years old or older. Many present with mildly decreased vision that cannot be corrected with glasses and the diagnosis is often delayed. Visual acuity is highly variable ranging from 20/20 to 20/200, but may decline with age and with complications such as vitreous hemorrhage and macular detachment.  The disorder is also associated with axial hyperopia, posterior subcapsular cataract and strabismus. Fluorescein angiography shows minimal or no leakage as opposed to cystoid macular edema. Focal areas of vascular leakage into schisis cavity may be present as well as peripheral capillary nonperfusion. Electroretinograms exhibit a reduced b-wave and a preserved a-wave.

Systemic Features: 

No general systemic manifestations are associated with juvenile retinoschisis.

Genetics

Juvenile retinoschisis is an X-linked recessive disorder that affects mainly males. The causative mutations involve the gene RS1 located on the X chromosome at Xp22. Female carriers may have peripheral schisis amd many allelic variants have been reported.  The encoded protein retinoschisin is a secreted protein produced by photoreceptors and bipolar cells and may be involved in cell-cell adhesion or ion channel regulation.

Treatment
Treatment Options: 

There is presently no effective treatment for the disorder, but decreased vision later in life can be aided with low vision aids. Cases with posterior subcapsular cataract can be treated with cataract extraction.  Improvement in the cystic macular lesions, central foveal zone thickness, and visual acuity have been reported to benefit from topical dorzolamide treatment.

References
Article Title: 

Peripheral fundus findings in X-linked retinoschisis

Fahim AT, Ali N, Blachley T, Michaelides M. Peripheral fundus findings in X-linked retinoschisis. Br J Ophthalmol. 2017 Mar 27. pii: bjophthalmol-2016-310110. doi: 10.1136/bjophthalmol-2016-310110. [Epub ahead of print].

PubMed ID: 
28348004

X-linked retinoschisis: an update

Sikkink SK, Biswas S, Parry NR, Stanga PE, Trump D. X-linked retinoschisis: an update. J Med Genet. 2007 Apr;44(4):225-32. 2006 Dec 15.

PubMed ID: 
17172462
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