Inherited retinal diseases, often shortened to IRDs, are a group of eye conditions caused by changes in genes that the retina needs to work.
The retina is the thin layer of tissue at the back of your eye. It works like the sensor in a camera. Light-sensing cells in the retina, called rods and cones, turn light into signals that travel to your brain.
Light comes in from the front of the eye (arrows at the bottom of the circle) and is caught at the top of each rod and cone, next to the RPE.
Illustration created with BioRender.com.
In an inherited retinal disease, a change in one gene, sometimes called a variant or mutation, stops these cells or their support cells from working normally. Over time, the cells can stop working or die.
More than 300 genes are known to cause IRDs. Each condition is rare, but together they affect roughly 1 in every 1,400 to 2,000 people. They are one of the most common causes of vision loss in children and working-age adults.
Everyone has two copies of most genes, one from each parent. IRDs can be passed down in different ways:
These are example families. The chances apply to each pregnancy separately, so real families can look different.
Sometimes no one else in the family is affected. That is common, especially for recessive conditions, and it does not rule out a genetic cause.
A short guide to some of the inherited retinal diseases we hear about most. Every person is different. Your own doctor can tell you what applies to you.
The most common IRD, affecting about 1 in 4,000 people. Rods are affected first, so the first signs are usually night blindness and slowly losing side vision ("tunnel vision"). Central vision is often kept until later in life. More than 80 genes can cause RP, including RHO, USH2A, RPGR and PRPF31.
The most common inherited condition of the macula, the center of the retina. It usually begins in childhood or the teenage years, but can start in adulthood. Central vision becomes blurry while side vision usually stays. It is most often caused by changes in both copies of the ABCA4 gene. Many retina specialists advise avoiding vitamin A supplements beyond a normal diet. Ask your doctor what is right for you.
Caused by changes in the BEST1 gene. A yellow, egg-yolk-like spot forms under the macula. Many people keep good vision for years, and the condition can be mild even within the same family. A related recessive form, called autosomal recessive bestrophinopathy, is also caused by BEST1.
Severe vision loss that starts in the first months of life. Babies may have shaky eye movements (nystagmus) and may not follow faces. Genes include CEP290, GUCY2D, CRB1 and RPE65. For changes in both copies of RPE65, an FDA-approved gene therapy exists. See treatments below.
Retinitis pigmentosa together with hearing loss, and sometimes balance problems. It is the most common cause of combined deafness and blindness. There are three main types. Type 2, often caused by USH2A, is the most common.
Mostly affects males. It begins with night blindness, then a slow loss of side vision as the retina and the blood vessel layer beneath it (the choroid) waste away. Central vision often lasts until later in life. Women who carry the change may have mild findings.
Affects boys and men. The layers of the retina split apart, most often in the center, which reduces reading vision from childhood. Regular eye checks matter, because complications such as bleeding inside the eye or retinal detachment can happen.
Cones are affected before rods. Early signs are blurry central vision, trouble with colors and discomfort in bright light. Night vision and side vision may be affected later. Many genes are involved, including ABCA4, GUCY2D, CRX and PRPH2.
The cones do not work from birth. People have very limited color vision, strong light sensitivity, shaky eye movements and reduced sharpness of vision. It usually changes little over time. Tinted glasses can make a big difference.
Tiny shiny crystals form in the retina, followed by slow loss of the retina and choroid. It is more often found in people of East Asian ancestry. Symptoms often start in the 20s or 30s with night vision problems and patchy vision loss.
For most IRDs there is not yet a treatment that stops or reverses vision loss. That is changing.
GeneReviews (NCBI); National Eye Institute; American Academy of Ophthalmology; RetNet, the Retinal Information Network; Hanany M, et al. PNAS 2020 (global prevalence of IRDs); U.S. Food and Drug Administration.