Atrophy of gyrate (girate)
Last reviewed: 23.04.2024
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Lobular atrophy of the choroid (atrophy of gyrate) is a disease inherited in an autosomal recessive type, with a characteristic clinical picture of atrophy of the choroid and pigment epithelium. Already at the beginning of the disease the field of vision is narrowed, night vision and visual acuity are reduced, ERG is absent. The severity of degenerative changes on the fundus does not correlate with visual acuity. Atrophy of gyrate (atrophy of the choroid and retina due to a mutation in the ornithineketoacidaminotransferase gene) is an enzyme that catalyzes ornithine degradation. Enzyme deficiency leads to an increase in the level of ornithine in plasma, urine, cerebrospinal fluid and intraocular fluid.
Type of inheritance is autosomal recessive. It appears in the 2nd decade of life, accompanied by axial myopia and niktalopia.
Pathognomonic sign of this disease is an increase in the content of aminoorithinic acid in the blood plasma in 10-20 times.
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Symptoms (in order of manifestation)
- Peripheral areas of chorioretinal atrophy and degenerative changes in the vitreous body.
- The tendency to merge changes with the formation of a scalloped edge facing the ora serrata.
- Gradual spread to the periphery and to the center with preservation of the intact fovea to the last stages.
In comparison with choroidderemia there is a pronounced thinning of the retinal vessels.
- Electroretinogram pathological, later - extinct.
- The electro-oculogram is subnormal in the late stages of the disease.
- The PHAG reveals a clear boundary between normal and atrophic zones.
A characteristic ophthalmoscopic feature is the demarcation line that separates the zone from the normal chorio-capillary layer. The presence of changes confirms the results of the PHAG. The process begins at the middle periphery and extends both to the periphery and the center of the fundus.
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Treatment of atrophy gyrate (girate)
There are 2 clinically different subtypes of gyrate atrophy, depending on the response to pyridoxine (vitamin B6, which is able to normalize the serum and urine concentrations of ornithine.) The vitamin B6-sensitive forms tend to be less severe and progress more slowly.The diet with reduced ornithine content leads to a decrease in the concentration of ornithine and slows down the 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 content of proteins (in particular, arginine). Recently, attempts have been made to conduct gene therapy in the experiment
The prognosis is unfavorable, the cause of blindness in 4-6 decades of life is "geographical" atrophy. Reduced vision may occur earlier due to cataracts, cystic macular edema or the formation of the epiretinal membrane.