Retinoschisis refers to a splitting of the neurosensory retina. The phenotype of congenital X-linked retinoschisis (XLRS) is variable, even within families. In pediatric patients, foveal schisis, which appears as small, cystoid spaces and fine radial striae in the central macula (Fig 13-24), can be best seen with OCT and fundus autofluorescence imaging. Other presenting signs include parafoveal white dots. Schisis is occasionally absent on OCT imaging, even in molecularly confirmed disease. Central vision may initially be quite good and may remain stable for long periods but can eventually decline to 20/200 or worse.
Peripheral retinoschisis may occur in up to 50% of patients. In severe cases involving peripheral schisis, there may be extensive areas of inner retinal elevation resembling total or subtotal retinal detachment. Histologic studies have shown that the splitting in peripheral XLRS occurs in the outer plexiform and nerve fiber layers. Pigmentary deposits may develop in peripheral areas destroyed by the disease process, so advanced cases of XLRS may be mistaken for RP. Boys with XLRS frequently present with vitreous hemorrhages from torn retinal vessels in areas of retinoschisis. Areas of peripheral schisis and the associated absolute scotomas are best monitored by widefield perimetry (eg, HVF 60-4) because photographic documentation can be extremely difficult.
Figure 13-24 Juvenile retinoschisis. A, Color fundus photograph shows the characteristic pattern of macular schisis, a more consistent finding than peripheral changes. Vertical (B) and horizontal (C) OCT scans demonstrate schisis spaces in the middle layers of the macula.
(Courtesy of Mark W. Johnson, MD.)
The panretinal involvement and inner retinal location of the disease are reflected in the ERG response, which has a negative waveform in which the a-wave is normal or near normal, but the b-wave is reduced (see Chapter 3, Fig 3-2).
In XLRS, the gene RS1 encodes an adhesion protein called retinoschisin, which is crucial for the structural integrity of the retina provided by the Müller cells. Treatment with topical and/or oral carbonic anhydrase inhibitors can be effective in reducing the intraretinal fluid in the central schisis cavities and may help to preserve long-term central vision function. A clinical trial of a gene therapy for this condition was initiated in 2016.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.