corneal deposits

Bietti Crystalline Corneoretinal Dystrophy

Clinical Characteristics
Ocular Features: 

The retina contains refractile glistening intraretinal crystals at all levels and choroidal vessels are said to be sclerosed.  The RPE atrophies and often forms pigment clumps.  The yellow-white crystals may be seen in the peripheral cornea and in the limbus.  Symptoms of night blindness and early vision loss begin about the third decade.  Night blindness is progressive as is the narrowing of the visual fields but this is highly variable between patients.  The visual field may show paracentral scotomas at some stage.  Central acuity can be normal until late in the disease when it becomes markedly impaired. Legal blindness can occur by the 5th decade of life. 

The ERG may show lack of rod and cone responses late in the disease and color vision may be lost.  However, the ffERG and mfERGs show decreases in amplitude of scotopic and photopic responses in all patients, even younger ones.  The EOG becomes abnormal in late stages.  The degree of involvement may be asymmetrical.  Complex lipid inclusions can be seen histologically in choroidal, conjunctival and skin fibroblasts, as well as in keratocytes and lymphocytes.

Crystalline deposits have been detected mostly in the proximal portions of RPE cells adjacent to degenerated retinal  areas.  Most common are circular hyperrefractive structures in the outer nuclear layer adjacent to areas of degeneration.  Some patients have cystoid macular edema. Others in late stages have fundus changes that resemble choroideremia.

Systemic Features: 

No other organ disease has been reported.


This is an autosomal recessive disorder caused by mutations in the CYP4V2 gene (4q35.1) involved in fatty acid metabolism.

A homozygous CYP4V2 mutation has also been reported in patients with a choroideremia-like clinical phenotype.

Autosomal recessive
Treatment Options: 

No treatment beyond low vision aids is available.

Article Title: 

Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2

Li A, Jiao X, Munier FL, Schorderet DF, Yao W, Iwata F, Hayakawa M, Kanai A, Shy Chen M, Alan Lewis R, Heckenlively J, Weleber RG, Traboulsi EI, Zhang Q, Xiao X, Kaiser-Kupfer M, Sergeev YV, Hejtmancik JF. Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2. Am J Hum Genet. 2004 May;74(5):817-26. Epub 2004 Mar 23.

PubMed ID: 
Subscribe to RSS - corneal deposits