Atrophy of gyrate.

Lobular atrophy of the choroid (gyrate atrophy) is a disease inherited in an autosomal recessive manner with a characteristic clinical picture of atrophy of the choroid and pigment epithelium. Already at the onset of the disease, the visual field is narrowed, night vision and visual acuity are reduced, ERG is absent. The severity of degenerative changes in the fundus does not correlate with visual acuity. Gyrate atrophy (atrophy of the choroid and retina due to a mutation in the ornithine ketoacid aminotransferase gene) is an enzyme that catalyzes the process of ornithine degradation. Enzyme deficiency leads to an increase in the level of ornithine in plasma, urine, cerebrospinal fluid and intraocular fluid.

The inheritance type is autosomal recessive. It manifests itself in the 2nd decade of life, accompanied by axial myopia and nyctalopia.

The pathognomonic sign of this disease is an increase in the content of aminoornithinic acid in the blood plasma by 10-20 times.

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Symptoms (in order of appearance)

• Peripheral areas of chorioretinal atrophy and degenerative changes in the vitreous body.
• Tendency for changes to merge with the formation of a scalloped edge facing the ora serrata.
• Gradual spread to the periphery and to the center with preservation of an intact fovea until the last stages.

Compared to choroideremia, there is marked thinning of the retinal vessels.

• Electroretinogram is pathological, later - extinct.
• The electrooculogram is subnormal in the late stages of the disease.
• FAG reveals a clear boundary between normal and atrophic zones.

A characteristic ophthalmoscopic sign is the demarcation line separating the zone of relatively normal choriocapillary layer. The presence of changes is confirmed by the results of FAG. The process begins in the middle periphery and spreads both to the periphery and to the center of the fundus.

Treatment of gyrate atrophy

There are 2 clinically distinct subtypes of gyrate atrophy depending on the response to pyridoxine (vitamin B6, which can normalize serum and urinary ornithine concentrations. Vitamin B6-sensitive forms tend to be less severe and progress more slowly. A diet with reduced ornithine content leads to a decrease in ornithine concentrations and slows progression.

The use of vitamin B ₆ in the treatment of this disease is pathogenetically justified, since it reduces the level of ornithine in the plasma. However, most patients do not respond to the introduction of vitamin B ₆, so the main method of treatment is a diet with a reduced protein content (in particular, arginine). Recently, attempts have been made to conduct experimental gene therapy

The prognosis is unfavorable, the cause of blindness in the 4-6 decades of life is "geographical" atrophy. Vision loss can occur earlier due to cataracts, cystoid macular edema or the formation of an epiretinal membrane.