Clinical Guidance

Bietti crystalline dystrophy (BCD) is characerized by progressive chorioretinal degeneration with onset typically during the second to third decade of life (range: early teens to 3rd decade). The symptoms, ranges of visual impairment, and disabilities are similar to those of individuals with autosomal recessive retinitis pigmentosa. The presenting symptom, rate of disease progression, and disease severity are also highly variable in BCD, even among those of the same age, within the same family, and with the same CYP4V2 pathogenic variants . Some individuals have a more diffuse retinal disease presentation, whereas others present with more localized disease in the paracentral and central regions. Vision impairment.

Diagnostic Criteria

The diagnosis of BCD, a chorioretinal degeneration, is based on the clinical findings of the typical crystalline deposits in the cornea and retina. BCD is one of few ocular diseases for which the diagnosis can be made with a high degree of confidence by careful examination alone.

Suggestive Findings

Bietti crystalline dystrophy should be suspected in individuals with the following clinical, electrophysiology, and optical coherence tomography (OCT) findings.

Clinical Findings

Vision impairment. Onset of impairment is typically during the second or third decade of life; however, age of onset, presenting symptoms, and disease severity vary widely. Vison impairment is progressive. Marked asymmetry between eyes is common.

Management Guidelines

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs of an individual diagnosed with Bietti crystalline dystrophy (BCD), the evaluations summarized in this section (if not performed as part of the evaluation that led to the diagnosis) are recommended:

Surveillance Guidelines

Ophthalmologic examination is recommended every one to two years to monitor disease progression. Examination should include visual field testing particularly as it relates to determination of driving eligibility and eligibility for government programs and/or disability. Affected individuals should be aware of the possibility of CNV and the option of self-monitoring using an Amsler grid under direction of their primary care ophthalmologist.

Source: GeneReviews — "Bietti Crystalline Dystrophy"