From OMIMBietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal dystrophy characterized by numerous tiny glistening yellow-white crystals at the posterior pole of the retina, associated with atrophy of the retinal pigment epithelium (RPE), pigment clumps, and choroidal sclerosis. Most cases have similar crystals at the corneoscleral limbus. The disorder is progressive; most patients develop decreased vision, nyctalopia, and paracentral scotomata between the second and fourth decades of life. Patients later develop peripheral visual field loss and marked visual impairment, usually progressing to legal blindness by the fifth or sixth decade of life. In a series of European patients diagnosed with nonsyndromic retinitis pigmentosa (RP; see 268000), BCD accounted for approximately 3% of all nonsyndromic RP and 10% of nonsyndromic autosomal recessive RP. Histopathology shows advanced panchorioretinal atrophy, with crystals and complex lipid inclusions seen in choroidal fibroblasts, corneal keratocytes, and conjunctival and skin fibroblasts, as well as in circulating lymphocytes, suggesting that BCD may result from a systemic abnormality of lipid metabolism (summary by Li et al., 2004).
http://www.omim.org/entry/210370 From MedlinePlus GeneticsBietti crystalline dystrophy is a disorder in which numerous small, yellow or white crystal-like deposits of fatty (lipid) compounds accumulate in the light-sensitive tissue that lines the back of the eye (the retina). The deposits damage the retina, resulting in progressive vision loss.
People with Bietti crystalline dystrophy typically begin noticing vision problems in their teens or twenties. They experience a loss of sharp vision (reduction in visual acuity) and difficulty seeing in dim light (night blindness). They usually lose areas of vision (visual field loss), most often side (peripheral) vision. Color vision may also be impaired.
The vision problems may worsen at different rates in each eye, and the severity and progression of symptoms varies widely among affected individuals, even within the same family. However, most people with this condition become legally blind by their forties or fifties. Most affected individuals retain some degree of vision, usually in the center of the visual field, although it is typically blurry and cannot be corrected by glasses or contact lenses. Vision impairment that cannot be improved with corrective lenses is called low vision.
https://medlineplus.gov/genetics/condition/bietti-crystalline-dystrophy