Gyrate atrophy of the choroid and retina associated with hyperornithinaemia

Abstract

A detailed ophthalmological examination was performed on 15 patients with gyrate atrophy of the choroid and retina. The fundus changes were grouped into 4 stages according to the progression of the disease. The youngest patients (Stage I) showed round, separate, or fused atrophic areas in the midperiphery of the fundus. In fluorescein angiographic studies a broad zone of pigmentary changes was observed between the normal looking and the atrophic areas. At Stage II the atrophic areas became more fused and advanced toward the posterior pole and a sharply defined demarcation line between the normal looking and atrophic area was seen in fluorescein angiograms. At Stage III a large degenerative area around the disc was seen and at Stage IV all of the posterior pole except for the macula was atrophic. Around the atrophic areas fine pigmentation was detected. With the progression of the disease, an abundance of this fine, dense, velvet like pigment was seen in the macula and peripheral retina. At the late stage the pigmentation hid all the choroidal vessels from view. Colourless, elongated, glittering crystals were found on the fine pigmentation in this study during contact lens biomicroscopy. The primary site of the lesion in this disease is thought to be at the level of the pigment epithelium/ choriocapillaris, because the EOG was highly pathological in all patients and marked changes were visible in fluorescein angiograms. The dark adaptation curves showed a progressive lesion in rod function. The cone function was spared even late in the disease, as seen in color vision studies. Myopia and complicated cataract were present in all patients. Patients with gyrate atrophy of the choroid and retina had an increased plasma, cerebrospinal fluid, and aqueous humour ornithine concentration, which was 10 to 20 times higher than normal. Defective activity of the enzyme ornithine ketoacid aminotransferase is probably the origin of this inborn error of amino acid metabolism.