Observation of the characteristics of the natural course of Bietti crystalline dystrophy by fundus fluorescein angiography

Abstract

Background: Bietti crystalline dystrophy (BCD) is an autosomal recessive genetic disorder that causes progressive vision loss. Here, 12 patients were followed up for 1-5 years with fundus fluorescein angiography (FFA) to observe BCD disease progression.

Methods: FFA images were collected for 12 patients with BCD who visited our clinic twice or more over a 5-year period. Peripheral venous blood was collected to identify the pathogenic gene related to the clinical phenotype.

Results: We observed two types in FFA images of patients with BCD. Type 1 showed retinal pigment epithelium (RPE) atrophy in the macular area, followed by choriocapillaris atrophy and the subsequent appearance of RPE atrophy appeared at the peripheral retina. Type 2 showed RPE atrophy at the posterior pole and peripheral retina, followed by choriocapillaris atrophy around the macula and along the superior and inferior vascular arcades and the nasal side of the optic disc. The posterior and peripheral lesions of both type 1 and type 2 BCD subsequently extended to the mid-periphery; finally, all the RPEs and choriocapillaris atrophied, exposing the choroid great vessels, but type 2 macular RPE atrophy could last longer.

Conclusions: The characterization of two different types of BCD development provides a better understanding of the phenotype and the progression of the disease for a precise prognosis and prediction of pathogenesis.

Keywords: Bietti crystalline dystrophy; Disease development; Fundus fluorescein angiography.

Fig. 1

Fundus colour photographs from the first and last visits of a patient with BCD. a, b Choroidal great vessels appear more clearly than before. c, d The RPE-choriocapillaris complex atrophy of the macular area shows no significant changes, but the RPE-choriocapillaris complex of the area around the macular area is more atrophied than before. e, f A scar caused by choroidal neovascularization is observed at the macular area, which was not apparent at the first visit. G, H The degree of pigment clumping has increased, and the choroidal great vessels appear more clearly than at the first visit

Fig. 2

FFA image jigsaws of the first and last visits of P3, P5, and P9. a, b The lesion has expanded to the mid-periphery from the posterior pole and periphery. c, d As the posterior pole lesion develops, new lesions appear in the periphery. e, f The RPE-choriocapillaris complex shows significant atrophy since the first visit; the border of the choriocapillaris atrophy and RPE atrophy is not as clear as at the first visit

Fig. 3

FFA image jigsaws of the first and last visits of P6 and P11. a, c At the first visit, both eyes of P6 show RPE atrophy at the posterior pole, the nasal side of the optic disc, and the periphery. b, d At the last visit, the posterior and peripheral lesions have expanded to the mid-periphery, and patches of choriocapillaris atrophy appear at the nasal side of the optic disc, the periphery, and along the superior and inferior vascular arcades. A choroidal neovascularization scar is seen at the macular area of the left eye of P6 with surrounding annular hypo-fluorescence. e, f The RPE atrophy of the macular area shows no significant changes, but the atrophy of the rest of the fundus area shows marked changes

Fig. 4

FFA image jigsaws of the first and last visits of P4 and P7. a, b, c Three FFA image jigsaws of the left eye of P4 taken at two-year intervals. The lesion has expanded to the mid-peripheral retina from the posterior pole retina and peripheral retina. d, e, f Three FFA image jigsaws of the right eye of P7 taken at two-year intervals. The majority of the choriocapillaris has atrophied. The remaining temporal peripheral choriocapillaris shows further atrophy over time