Swept-source Optical Coherence Tomography Angiography in a Patient with Bietti Crystalline Dystrophy Followed for Ten Years

Şefik Can İpek; Ziya Ayhan; Sibel Kadayıfçılar; Ali Osman Saatci

doi:10.4274/tjo.galenos.2018.90768

ABSTRACT

A woman with Bietti’s crystalline dystrophy (BCD) was first examined when she was 27 years of age and has been followed for 10 more years. The disease course was monitored initially with spectral domain-optical coherence tomography and then with swept-source optical coherence tomography angiography (OCTA). OCTA analysis showed that choroidal vessels could be visualized at the outer retinal layer segmentation due to retinal pigment epithelial atrophy and blood flow was reduced at the level of choroidal segmentation. OCTA can play a major role in the follow-up of BCD patients by analyzing changes in choroidal flow.

Keywords:

Bietti crystalline dystrophy, optical coherence tomography, optical coherence tomography angiography, retinal dystrophy

Introduction

Bietti crystalline dystrophy (BCD) is a retinal dystrophy characterized by shiny yellow crystalline deposits in the retina and sometimes the limbus with progressive chorioretinal atrophy starting in the posterior pole.¹ Mutations in the CYP4V2 gene have been detected in patients with BCD.²

Indocyanine green angiography, one of the conventional imaging methods, shows extensive areas of hypofluorescence due to choriocapillaris atrophy as the disease progresses in posterior pole.³ Optical coherence tomography has demonstrated reduced central foveal and subfoveal thickness, hyperreflective spots in all retinal layers and even within the choroid, outer retinal tubulations, and hyperreflective plaques in the retinal pigment epithelium (RPE)-Bruch’s membrane complex.⁴

Compared to conventional methods, there are fewer reports of findings associated with BCD in optical coherence tomography angiography (OCTA), which is a very new imaging modality. In this case report, we describe the clinical entities and OCTA characteristics of a woman with BCD who was followed for 10 years.

Discussion

Hirashima et al.⁵ used SS-OCTA to evaluate 9 eyes of 9 patients with BCD, 16 eyes of 16 retinitis pigmentosa patients with EYS mutation, and 16 eyes of 16 control subjects. The outer choroidal vascular area was 43.34±5.76% in eyes with BCD, 53.73±4.92% in eyes with EYS mutation/retinitis pigmentosa, and 52.80±4.10% in healthy subjects, with the value in BCD being significantly lower. Thinning in the outer choroidal vascular area in eyes with BCD was associated with thinning of the subfoveal choroid, and interestingly, the inner choroidal vessels could not be identified in 8 of the 9 BCD eyes.

Miyata et al.⁶ analyzed 13 eyes of 13 patients with BCD using Optovue OCTA (RTVue XR, Avanti-AngioVue, Optovue, Freemont, CA, USA) and demonstrated reduced choriocapillaris flow in 12 (92%) of the 13 eyes. The authors reported that subfoveal choriocapillaris thickness was correlated with visual acuity.

In our patient, after 10 years of follow-up, we observed a slight decline in vision, which was already poor at baseline, reduction of intraretinal crystals, and substantial progression of chorioretinal atrophy. Consistent with the publications cited above, we noted a significant decrease in choriocapillaris flow in SS-OCTA performed 10 years after the first examination.

We believe that OCTA will become an important adjunctive examination in the follow-up of choroidal blood flow and changes in the choroidal vasculature in BCD, a disease that causes progressive vision loss.

References

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