Intrascleral and Peripheral Retinal Crystals in Bietti Crystalline Dystrophy

To report a case of intrascleral crystal deposition in a patient with genetically confirmed Bietti Crystalline Dystrophy (BCD).

Case report of a 51-year-old Asian male with high myopia, nyctalopia since early adulthood and progressive visual decline. Clinical examination, fundus photography, infrared reflectance, spectral-domain OCT, and ultra-widefield swept-source (SS) OCT were performed. Genetic testing was performed to evaluate for pathogenic mutations in CYP4V2 .

Pseudocolor fundus photography revealed yellow-white crystalline deposits primarily in the posterior pole with poor visualization of crystals more peripherally. Cross-sectional OCT localized hyperreflective deposits predominantly at the retinal pigment epithelium-Bruch's membrane complex, with additional foci in the outer and inner retina, accompanied by chorioretinal atrophy. Intrascleral crystals were also identified on spectral domain OCT. Ultra-widefield OCT extended the assessment beyond the vascular arcades, revealing peripheral zones of atrophy and scattered crystals not visible on standard field scans.

Intrascleral crystal distribution may aid in broadening the phenotypic spectrum of BCD, supporting more accurate diagnosis and contributing to the understanding of its pathophysiology. UWF and multimodal imaging provide complementary insights into BCD extent and crystal localization. Infrared reflectance outperforms pseudocolor photography for crystal detection, while UWF-OCT expands structural evaluation into the periphery, potentially improving monitoring strategies.