20/09/2025
Progressive night blindness and peripheral visual field constriction
🩺 A 25-year-old woman of asian ethnicity presents with progressive night blindness and peripheral visual field constriction, which she first noticed in adolescence. She reports increasing difficulty driving at night and frequent stumbling in dimly lit environments. Her central vision is relatively preserved, though she complains of occasional glare and photophobia.
👁️ Dilated fundus examination reveals multiple tiny, glistening, yellow-white refractile crystalline deposits scattered in the posterior pole, particularly in the macular and perimacular regions.
💡 Given the characteristic clinical features in association with the distinctive crystalline retinal deposits, Bietti crystalline dystrophy is strongly suspected. Genetic testing subsequently identifies a mutation in the CYP4V2 gene, thereby confirming the diagnosis.
📝 Bietti crystalline dystrophy is a rare autosomal recessive retinal dystrophy caused by mutations in the CYP4V2 gene, leading to defective lipid metabolism and crystalline deposits in the retina and sometimes cornea. It usually presents in the second or third decade of life with progressive nyctalopia, peripheral visual loss, and eventual decline in central vision. There is currently no definitive treatment; management is supportive with low-vision aids, genetic counseling, and monitoring for progression. Research into gene-based therapies and lipid metabolism modulation is ongoing, but clinical application remains experimental.