Gyrate atrophy of the choroid and retina is a rare, inherited disorder that primarily affects the eyes, leading to progressive vision loss. It is caused by a deficiency in an enzyme called ornithine aminotransferase (OAT). This enzyme is crucial for breaking down ornithine, an amino acid found in the body. When OAT is deficient or absent, ornithine accumulates to toxic levels in the blood, urine, and various tissues, particularly the eyes.
The condition typically first becomes apparent in childhood. The earliest symptom is often night blindness (nyctalopia), making it difficult to see in low-light conditions. As the disease progresses, individuals may experience a gradual loss of peripheral vision, often described as "tunnel vision." This occurs because the disease causes the progressive degeneration of the choroid (the vascular layer of the eye) and the retina (the light-sensitive tissue at the back of the eye). During an eye exam, a doctor may observe characteristic circular patches of atrophy in the peripheral retina that slowly merge and move toward the center over time.
In addition to vision problems, gyrate atrophy can also cause early-onset cataracts (clouding of the eye's lens) and severe nearsightedness (myopia). While the eyes are the most significantly affected organs, the condition can also have systemic effects. Some individuals may experience mild muscle weakness, particularly in the skeletal muscles, and in rare cases, mild cognitive impairment or delayed speech development has been reported.
Because gyrate atrophy is a genetic condition, it is inherited in an autosomal recessive pattern. This means an individual must inherit two copies of the mutated OAT gene—one from each parent—to develop the disease.
Currently, there is no cure for gyrate atrophy, but early diagnosis is critical. Management focuses on slowing the progression of vision loss, primarily through strict dietary modifications aimed at reducing ornithine levels in the body. Regular monitoring by an ophthalmologist and a metabolic specialist is essential for managing the condition effectively. Patients should always consult their healthcare provider for personalized medical advice and treatment plans.