This study will explore the causes and eye problems of X-linked juvenile retinoschisis (XLRS), an inherited disease that causes vision loss primarily in young males. The vision loss, which worsens over time, is a result of schisis, or splitting, of the layers of the retina (tissue that lines the back of the eye). A better understanding of why and how XLRS develops might lead to improved treatments.

Patients 9 months of age and older with XLRS and females who are suspected carriers of the gene responsible for the disease (such as the mother of the patient) may be eligible for this study. Other family members of patients also may be enrolled.

Patients will undergo the following tests and procedures:

• Personal and family medical history to review past and current medical conditions and treatments, particularly regarding eye disease, and to construct a family tree.
• Eye examination to assess visual acuity (eye chart test) and examine pupils, lens, retina, and eye movements. The pupils will be dilated with drops for this examination.
• Photography of the retina to help evaluate the status of the retina.
• Specialized eye tests to evaluate color vision, field of vision, and ability to see in the dark.
• Electroretinogram (ERG) to examine what happens to the eyes after a flash of bright light. For this test, the patient sits in a dark room for 30 minutes with his or her eyes patched. Then, a small silver disk electrode is taped to the forehead, the eye patches are removed, the surface of the eye is numbed with eye drops and contact lenses are placed on the eyes. The patient looks inside a large empty bowl and then a light flashes, first in the dark and then with a light turned on inside the bowl. The contact lenses sense small electrical signals generated by the retina when the light flashes.
• Blood test to examine DNA for genetic study of XLRS.

Family members will provide a blood sample for genetic study.