Last month, we explored how we inherit more than eye color. Genes can influence our risk for eye disease, raising the question: If our DNA can reveal risks, should we all have genetic testing? The answer depends on what we hope the results will tell us.

When it Helps

Sometimes an examination, symptoms, or family pattern can suggest an inherited disorder, and genetic testing could provide important information. A laboratory evaluates DNA from a blood or saliva sample, looking at one gene or, more commonly, a panel of genes associated with an eye condition. An eye doctor or genetic counselor explains the results and recommends next steps.

Testing is most useful for conditions such as retinitis pigmentosa, Stargardt disease, or some corneal dystrophies and optic nerve conditions.

It is less useful for common conditions such as glaucoma, macular degeneration, and nearsightedness. Age, health, and environment play important roles, so genetic testing alone cannot provide a diagnosis or replace regular eye examinations.

Why Do It

Many inherited eye diseases can look similar even when caused by different gene variants. Identifying the responsible gene may confirm a diagnosis, explain how it was inherited, and help determine if relatives are at risk.

Sometimes testing reveals that an eye problem is part of a broader condition, one that may affect hearing, the kidneys, or another part of the body.

A genetic diagnosis may help determine whether someone qualifies for a clinical trial or gene-specific treatment. For example, the first FDA-approved gene therapy for an inherited retinal disease is available for patients with disease-causing changes in both copies of the RPE65 gene. Most inherited eye disorders do not yet have approved gene therapies, but a growing number of treatments are in development.

What It Means

Results are not always definitive. A positive result identifies a genetic change believed to cause or contribute to disease. It cannot reliably predict when symptoms will appear or how severe they will become.

A negative result does not necessarily rule out a genetic disorder. The responsible gene may not yet be known, or today's tests may not detect every genetic change.

Sometimes testing finds a "variant of uncertain significance." Simply put, the test identified a DNA difference that has not yet been classified as harmful or harmless.

The important question is whether the result could clarify a diagnosis or guide care. For people with inherited eye disease, a string of DNA letters could help clinicians provide answers and open the door to new treatment options.

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