Convoluted chorioretinal atrophy

Introduction to convoluted choroidal retinal atrophy The gyrateatrophy of choroidandretina (GA) is a hereditary disease associated with amino acid metabolism disorders. Usually starting from the equator, expanding to the center and the surrounding area, and finally involving most of the fundus, can cause serious visual dysfunction. basic knowledge The proportion of illness: 0.001% Susceptible people: no specific population Mode of infection: non-infectious Complications: cataract myopia, retinitis pigmentosa, no choroidal disease, nystagmus, muscular dystrophy

Circumferential chorioretinal atrophy

(1) Causes of the disease

The disease is an autosomal recessive genetic disease, and very few are autosomal dominant genetic diseases.

(two) pathogenesis

Due to the variation and deficiency of the ornithine ketoacid transaminase (OKT) gene, the disease causes hyperornithemia in the body, and ornithine accumulates in the choroid, affecting its metabolism and causing disease. The study confirmed that the patient's plasma, aqueous humor and urinary ornithine determination were higher than normal, OKT function was insufficient, and its vitality was lower than normal. Smell and Takki first reported plasma, urine, cerebrospinal fluid and aqueous humor in 9 patients with this disease. The ornithine determination was 10-20 times higher than that of the normal control group. Therefore, the disease is related to hyperornithinemia. The ornithine metabolic pathway is involved in three enzyme metabolic reactions, and 0KT is a catalytic bird. An important enzyme of acid metabolism, due to the defect of OKT, can cause the accumulation of ornithine, the production of glutamic acid and proline is reduced, and the defects of the enzyme cause the fundus lesion. Kaiser-Kupfer transforms lymphoblasts through the culture medium. In the determination of the amount of OKT, it was confirmed that there is no OKT activity in lymphoblasts of patients with choroidal atrophy, and the damage of retinal pigment epithelial cells may be caused by excessive ornithine, which is probably the disease. Cause.

Kaiser-Kupfer stimulates lymphocytes with phytohemagglutinin for transformation, and the activity of transformed lymphocyte ornithine aminotransferase (OAT) is increased by 15 times. The enzyme activity is easy and reliable, and patients are compared with normal. The OAT activity of transformed lymphocytes in the control group showed significant differences, and the lack of OAT activity was also the main cause of the disease, indicating that OKT and OAT deficiency could not catalyze the conversion of ornithine to glutamate, resulting in hyperornithemia, birds. The concentration of amino acid in the blood can directly or indirectly have toxic effects on muscle cells, fibroblasts and RPE cells.

In the female carrier of the disease (heterozygous), the plasma ornithine concentration was normal, but for the ornithine load test, the ornithine retention in the plasma after oral ornithine was administered, and the activity of OKT was measured and found to be normal. There is no parallel relationship between the degree of ocular lesions and plasma ornithine concentration between humans and patients. The blood levels of ornithine in normal patients are normal. Fell et al reported that there are no patients with hyperornithemia. The disease manifests itself, ERG is normal, but there are severe neurological disorders and mental retardation. The ornithine-proline metabolism of the retina has been found to have high OKT activity in the iris, ciliary body, retina and choroid of the human eye. The active tissue distribution of this enzyme is closely related to retinal choroidal atrophy.

Circumferential chorioretinal atrophy prevention

Prevention should focus on the detection of heterozygotes. For those with family history, prenatal examination can be performed, heterozygotes can be detected, amniocentesis can be used for cell culture, and enzyme activity can be measured. According to the degree of degradation of ornithine metabolism in fibroblasts, Heterozygotes, homozygotes are separated from normal people. If the fetus has ornithineemia, there may be ornithine urine, and the ornithine concentration in the amniotic fluid may be increased. After the detection, prophylactic treatment is given to achieve early diagnosis. Early treatment.

Complications of convoluted chorioretinal atrophy Complications cataract myopia retinitis pigmentosa without choroidal dysfunction dystrophic muscle dystrophy

Circumferential choroidal atrophy can be secondary to cataract, especially after posterior polar cataract. Almost all patients develop posterior subcapsular cataract when they are 20 years old. Most patients have different degrees of myopia, and they are progressive, and they can be combined. Other defects, such as retinitis pigmentosa, white spotted retinal degeneration, no choroidal disease, iris atrophy, nystagmus, strabismus, congenital amaurosis, finger licking, infancy, movement disorders, muscular dystrophy, mental retardation, mild brain Electrogram abnormalities and hair changes and hair is thin and small.

Circumferential choroidal retinal atrophy symptoms common symptoms visual impairment lens opacity visual field defect fundus changes night blindness

Visual dysfunction

Most of the patients started to have night blindness before 10, and as the disease progresses, the central vision decreases, and gradually increases with age. When the lesion involves the macula, the vision is extremely diminished, but only the light is left, usually 40 to 50 years old. The disease has color vision disorder. The visual field examination may have a ring-shaped dark spot in the early stage of the disease, and then the centripetal function is reduced. The visual field defect is consistent with the scope of the choroidal lesion. Before the macular function is lost, only a small central field of view remains, and the dark adaptation test shows early. The dark adaptation threshold is within the normal range, and the late threshold is increased to 20 to 40 log units. The color vision examination found that patients often have blue dysfunction (100-Hue test). The electrophysiological examination found that the initial ERG was lower than normal after normal, and finally disappeared. It is eccentric ERG is not normal, and then involves the ERP part of the clear vision, and finally ERG is extinguished, EOG has been significantly abnormal in the early stage of the disease, the peak potential is lowered, the late base potential is also decreased, and even EOG is extinguished, and oral treatment with vitamin B6 can be used. Improves the EBG's peak/dark valley, central vision is impeded in most cases with early myopia, but can be corrected; with the eye The development of lesions and lens opacity, decreased visual acuity also generally blindness in 40 to 60 years old.

2. Fundus changes

In the early stage of the patient's fundus, the choroid atrophy was clearly defined in the equator, the shape was irregular, the margin was serrated, and the fundus was normal between the atrophic plaques. The subsequent atrophy gradually expanded, and the scattered atrophy gradually merged into a piece, which was flower-ringed, and Extending to the posterior pole and the peripheral portion, a shrink ring can be formed around the optic disc, and an annular region with visual function can be formed between the ring and the atrophic ring of the equatorial portion. Finally, the fundus is yellowish white, almost all the fundus The extent is impaired, only the macular area is preserved (Fig. 1A). At this time, the fundus is similar to that without choroidal disease. The optic disc is waxy yellow or reddish. In advanced cases, pigmentation may occur, with needle-like crystals interspersed. In addition, the retina The blood vessels are narrow and the optic disc is pale. In most advanced cases of 40 to 60 years old, the posterior pole chorioretinal is extensively affected, and the fundus appearance is similar to late choroidal disease.

3. Fundus fluorescein angiography

In the early stage, a typical convoluted atrophy zone can be seen. The choroidal vessels in the atrophy area are clearly visible. Sometimes the pigment epithelium on the outer edge of the early atrophy is transparent, and the choroidal vessels are visible from here, and the fluorescent dye leaks around the blood vessel. The leakage area is larger than the extent of the lesion seen in the ophthalmoscope, indicating extensive damage to the pigment epithelium (Fig. 1B). After the atrophy of the late choroid, a strong scleral fluorescence occurs.

Examination of convoluted choroidal retinal atrophy

Genetic testing can determine its genetic pattern, blood nornithine concentration exceeds 400 mol / L and OKT activity is significantly reduced, and plasma uridine level or OAT activity in cultured epidermal fibroblasts can also be determined.

Diagnosis and differentiation of convoluted chorioretinal atrophy

Diagnostic criteria

The diagnostic criteria of this disease include: myopia, night blindness, cataract, progressive choroidal polymorphism, ERG amplitude reduction or disappearance, autosomal recessive inheritance, blood ornithine concentration over 400mol/L and OKT activity decreased significantly, the disease The diagnosis can be established by detecting the plasma uridine level of the patient and the carrier or the activity of OAT in the cultured epidermal fibroblasts. Since the normal human serum has a very low ornithine content and is limited by the instrument conditions, it is impossible to count the normal value. And the standard deviation, so can only show the highest value of normal people, some people measured 30 normal human serum ornithine, the highest value of not more than 56.6mol / L.

Differential diagnosis

No choroidal disease

In the advanced case of this disease, the fundus image is similar to that of no choroidal disease. There are small, velvety pigment hyperplasia and lustrous crystallized small spots in the peripheral fundus and macular area in the late stage of choroidal dysfunction, which is a typical change of this disease.

2. Diffuse choroidal capillary atrophy

The disease is a rare autosomal dominant hereditary disease in which choroidal capillary atrophy and pigment clustering begin in the posterior pole, leading to early vision loss.

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