Multimodal Imaging for Differential Diagnosis of Bietti Crystalline Dystrophy

Abstract

To evaluate the diagnostic usefulness of multimodal imaging in patients with Bietti crystalline dystrophy (BCD). Retrospective cross-sectional study. Patients with chorioretinal dystrophy accompanied by crystalline-like deposits. The right eyes of the patients were analyzed. Fundus photograph, near-infrared reflectance (NIR), fundus autofluorescence (FAF), and OCT images were evaluated. Presence of hyperreflectivity on NIR, well-demarcated areas of decreased FAF, hyperreflective material at or on the retinal pigment epithelium-Bruch's membrane complex, and outer retinal tubulation were graded for each patient. All exons and franking introns of CYP4V2 were screened using Sanger sequencing. Sensitivity and specificity of the findings to discriminate patients with and without CYP4V2 mutation. In total, 33 patients were included in the study. Sanger sequencing revealed homozygous or compound heterozygous CYP4V2 mutations in 20 patients and heterozygous mutations in 2 patients. Among the investigated factors, hyperreflective appearance on NIR imaging yielded 100% sensitivity and 100% specificity in this cohort. The presence of outer retinal tubulation also was sensitive (95%), but specificity was moderate (45%). The revised diagnoses of patients without CYP4V2 mutations included retinitis pigmentosa, late-onset macular dystrophy, and central areolar choroidal dystrophy. Multimodal imaging, especially NIR imaging, is useful to differentiate BCD patients with CYP4V2 mutations from patients with other chorioretinal dystrophies accompanied by crystalline-like retinal deposits.