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Healthy young child presents with decreased visual acuity
The posterior segments of both eyes had small cystoid spaces and fine radial striae in the central macula.
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A 5-year-old healthy boy presented with decreased visual acuity detected by ophthalmic examination. He denied any ocular pain, headaches, flashes, floaters, nyctalopia or progressive worsening of his visual acuity. He was full term and delivered via C-section due to breech position. His family ocular history was significant for a maternal uncle with poor vision from unknown etiology and an aunt with strabismus.
Examination
The patient’s best corrected visual acuity was 20/50-1 in the right eye with no improvement by pinhole and 20/40-3 in the left eye with no improvement by pinhole. There was no evidence of an afferent pupillary defect or anisocoria. His extraocular movements and IOPs were within normal limits. On slit lamp biomicroscopy, the anterior segments were normal, but the posterior segments of both eyes revealed small cystoid spaces and fine radial striae in the central macula, forming a “spoke-wheel pattern” (Figure 1). Optical coherence tomography of both eyes demonstrated splitting of the retinal layers (Figure 2).
Figure 1. Fundus photos demonstrating small, cystoid spaces and fine radial striae in the central macula, forming a spoke-wheel pattern.
Images: Sodhi AK, Reichel E
Figure 2. OCT of both eyes demonstrating splitting of the retinal layers.
What is your diagnosis?
Spoke-wheel pattern
The diagnosis of X-linked juvenile retinoschisis can be made based on funduscopic appearance, fluorescein angiography and OCT. Classically, there is a spoke-wheel pattern in the macula, representing an area of schisis of the nerve fiber layer. Schisis can occur in the peripheral retina, predominately inferotemporally, in approximately 50% of affected individuals.
Diseases that can appear funduscopically similar to X-linked juvenile retinoschisis include Goldmann-Favre vitreoretinal degeneration, nicotinic acid maculopathy and cystoid macular edema. The onset of Goldmann-Favre vitreoretinal degeneration occurs in infancy, and affected individuals generally have severely impaired vision, including marked visual field loss and severe night blindness, which our patient did not have. The electroretinogram in Goldmann-Favre vitreoretinal degeneration shows a marked reduction of the a-waves and b-waves, whereas in X-linked juvenile retinoschisis, there is only a reduction in the b-wave amplitude. In nicotinic acid maculopathy, there is a history of niacin use, which causes cystoid spaces in the inner nuclear and outer plexiform layers. These resolve with discontinuation of the drug. Cystoid macular edema can appear funduscopically similar but is typically associated with leakage on fluorescein angiography, a characteristic not inclusive of X-linked juvenile retinoschisis.
Discussion
X-linked juvenile retinoschisis was first described in 1898 by the Austrian ophthalmologist Haas as cysts in “wheel spokes,” and in 1935, Wilczek introduced the term “retinoschisis.” It is one of the more frequently inherited retinal disorders, affecting macular function in young males. The prevalence is one in 5,000 to 25,000 males, and the inheritance pattern is X-linked recessive with high penetrance. In 1997, a mutation in the XLRS1 gene that encodes a retinoschisis protein was identified to be the cause of this disease.
The diagnosis is seldom made in newborns and more often is made in early childhood due to symptoms of poor vision in school. Strabismus and nystagmus have been described but are not necessarily present. Children rarely complain of nyctalopia or peripheral vision loss. Vision typically ranges from 20/40 to 20/60 during late grade school and remains stable into middle age. Progressive macular atrophy begins in late middle age and contributes to a progressive decline in vision to around 20/200. In female carriers, clinical signs are subtle, mostly seen as loss of foveal reflex, subtle wrinkling of the internal limiting membrane or irregular macular pigmentation with usually normal electroretinogram. In the literature, extraocular manifestations have not been reported.
Clinically, foveal schisis is described as having a spoke-wheel configuration, which represents splitting between the nerve fiber layer and ganglion cell layer. In 50% to 70% of patients, peripheral retinoschisis is present and most often is localized in the inferotemporal quadrant. OCT shows widespread cystic spaces in both the inner and outer macular retina. Fluorescein angiography does not show leakage of dye in the area of macular cystic changes in early and late phases. Characteristically, electroretinograms have an electronegative appearance in scotopic response, with a normal a-wave and reduced b-wave.
Complications reported in the literature are typically vitreous hemorrhage or retinal detachment. Vitreous hemorrhage is thought to be due to the inner retinal layer “ballooning” into the vitreous cavity and causing unsupported retinal vessels to break. Retinal detachment has been reported to occur in 4% to 20% of cases and is often associated with vitreoretinal proliferation, thus making surgical stabilization difficult. Prophylactic photocoagulation treatment of retinal schisis is typically not recommended. In 1990, Castier et al reported 28 patients with poor outcomes after photocoagulation treatment. Further, most patients can spontaneously regress with age.
Unfortunately, there is currently no definitive treatment for retinoschisis. Genetic counseling is necessary and should be requested in severe forms. Patients with a family history or diagnosis of X-linked juvenile retinoschisis should be regularly examined to detect amblyopia, vitreous hemorrhage or retinal detachment.
Follow-up
Our patient has been followed yearly from age 5 years old to 13 years old, and his vision has remained stable at 20/50.
References:
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For more information:
Avneet K. Sodhi, MD, and Elias Reichel, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.Edited by Kavita Bhavsar, MD, and Michelle C. Liang, MD. They can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.