Juvenile Retinoschisis ~ Overview
Download a PDF version of this document.
Juvenile retinoschisis is a genetic condition that causes vision loss. It almost always affects boys usually starting in childhood. Juvenile retinoschisis causes a loss in central vision. In some cases, a person’s peripheral vision may also be damaged.
Juvenile retinoschisis should not be confused with senile retinoschisis. This is a condition of aging, which affects roughly equal numbers of men and women.
Medical Description
Retinoschisis literally means splitting of the retina. In this condition, tiny splits appear in the retina between the photoreceptor cells and the next layer of nerve cells which relay their signals to the brain. Cysts form in these splits often making a wheel-like pattern in the centre of the retina. This damage causes a loss of central vision. These splits and cysts also make the retina abnormally thick.
Retinoschisis may also cause similar splits in the farthest edges of the retina, causing a loss of peripheral (side) vision. This happens in about half of people with juvenile retinoschisis.
Over time, damage to the retina builds up causing progressive loss of vision.
Early Symptoms
The symptoms of juvenile retinoschisis are usually noticed about the time that a boy enters public school – although in families where the disease is inherited, and early testing is done, very young children may be diagnosed.
The most common symptoms are a general loss of vision and difficulty seeing fine detail. Some boys may also have nystagmus (rapid involuntary movements of the eye from side to side) and strabismus (eyes turned in or cross-eyed). Because of this, sometimes retinoschisis is initially diagnosed incorrectly as amblyopia (lazy eye).
Diagnosis
An ophthalmologist may suspect retinoschisis after a simple eye examination, particularly if a wheel-like pattern of splits is visible in the macula. However several tests can clarify and confirm the diagnosis:
- ERG (electroretinography) measures the electrical responses of the retina. During this test, a special contact lens is placed on the eye, and the eye is exposed to flashes of light.
- OCT (optical coherence tomography) makes digital images of the retinal layers.
- Genetic testing (starting with a blood sample) can identify the gene defects that cause juvenile retinoschisis.
What to Expect
Boys with retinoschisis usually have vision loss in grade school and may continue to lose vision into their teens. Once they are adults, their vision most often stabilizes until they are in their 50s or 60s.
Men with retinoschisis almost never lose their vision completely. However, they are more at risk of serious eye complications such as retinal detachment (5-20% have this complication) and bleeding into the vitreous body (jelly) of the eye (4-40%).
Women who are carriers of a damaged gene may also develop some vision loss later in life – most often of peripheral vision.
Treatment
No treatments are currently approved for retinoschisis. However, dorzolamide eye drops, developed and approved to treat glaucoma, may help reduce the cysts and thickening of the retina, particularly in younger patients. Although the drops may help reduce the early changes associated with retinoschisis, the effect on vision is usually modest. Side effects of dorzolamide eye drops include stinging or burning in the eye. Some children may also be allergic.
Patients of all ages should have regular eye exams even if their vision is not changing, to avoid the serious but treatable complications such as retinal detachments.
Genetic Causes
Juvenile retinoschisis is an X-linked condition. It is caused by defects in a gene, RS1 (retinoschisin 1), on the X chromosome. Several different changes (mutations) within this gene can cause the disease. Genetic testing can identify the specific mutation within the RS1 gene almost 95% of the time.
What is meant by “X-linked”?
Chromosomes are complex strings of genes. Each person has 23 pairs of chromosomes. One of each pair comes from your mother, the other one from your father. Thus, we have duplicate copies of most genes – a back-up against disease caused by gene damage.
One pair of chromosomes is different. These are the X and Y chromosomes that make us female and male. These sex chromosomes carry many different sorts of genes, but most of the genes on X are missing from Y. RS1 is one of these.
Women have two X chromosomes, one from their mother and one from their father.
Men have an X from their mother, and a Y from their father, thus men have no protective back-up if a gene on the X chromosome is defective.
For these reasons, usually only boys inherit retinoschisis. Rarely, a girl may inherit damaged genes on both X chromosomes and have the disease. More often, a girl inherits just one damaged gene, which she passes on to her children without having the disease herself.
Research
The Foundation Fighting Blindness supports scientists working to understand the causes of vision loss and to develop treatments for it. A Canadian researcher, Dr. Robert Molday, is a world leader in research on juvenile retinoschisis. He has been funded by the FFB in the past to study this disease, and he currently leads an international team of researchers funded by the FFB and the Canadian Institutes of Health Research, which aims to develop gene treatments for several genetic conditions – including retinoschisis. Other FFB-funded research, such as studies on the use of stem cells to replace the damaged retina, may benefit people with retinoschisis. To subscribe to our print and e-newsletters on the latest vision research, call 1.800.461.3331 today or email info@ffb.ca.
Additional Resources
Here are some additional sources of information about retinoschisis.
- X-linked Juvenile Retinoschisis from the US National Library of Medicine
-Retinoschisis, Juvenile from eMedicine
- Retinoschisis from the Kellogg Eye Center, Michigan
- X-linked Juvenile Retinoschisis from Orphan.Net
Reviewed April 2, 2012 by Dr. Kevin Gregory-Evans, Professor of Ophthalmology, University of British Columbia.