BCD Basics

How does the world change in our eyes?

“What do you see” is one of the questions we get asked frequently. Here we intent to illustrate the world we see as the blinding eye disease BCD progresses.

When we meet a person in life, we see:


When we go outside on a busy street, we see:


When the night comes, we see:


What is BCD?

Bietti’s Crystalline Dystrophy (BCD) is an underdiagnosed, rare, blinding genetic eye disease that could affect more than 100,000 people globally.
The crystal representation changes as BCD progresses.

Changes in crystal representation:


Courtesy of Dr. Qian Li and BCD patients

Basic information on BCD 1 2 3

  • It’s a blinding disease caused by progressive retinal degeneration.
  • Onset Age: People with Bietti Crystalline Dystrophy (BCD) typically begin noticing vision problems in their teens or twenties, with some cases reported even during the first decade of life.
  • Characteristics: Visible yellow or refractile crystal-like deposits in the retina and sometimes also in the cornea. Crystal deposits may disappear in late stage.
  • Symptoms: Vision problems include progressive night blindness, distorted vision, sensitive to strong light, reduced visual acuity, blind spots in visual fields, reduced contrast sensitivity, impaired color vision, and eventually legal blindness.
  • Gene: Caused by mutations in CYP4V2 gene. To date, over 100 BCD-causing mutations in CYP4V2 gene have been reported.
  • Inheritance pattern: Autosomal recessive inheritance pattern. Many patients do not have a family history.
  • Misdiagnosis: BCD is often misdiagnosed due to its low awareness. Patients have reported that they were diagnosed as having unknown cause of crystalline. BCD can also be misdiagnosed as: Stargardt Disease, dominant forms of RPE65, Retinitis Pigmentosa (RP) in general, etc. Read more in Misdiagnosis and Underdiagnosis

BCD diagnosis in a nutshell


Various names of BCD (BCD Synonyms)

  • Bietti’s Crystalline Dystrophy (BCD)
  • Bietti Crystalline Dystrophy
  • Bietti’s crystalline retinopathy
  • Bietti crystalline corneoretinal dystrophy
  • Bietti’s crystalline corneoretinal dystrophy
  • Bietti’s retinal dystrophy
  • Bietti crystalline chorioretinal dystrophy
  • Bietti’s tapetoretinal degeneration

BCD in other languages:

  • Spanish: Distrofia cristalina de Bietti
  • German: Bietti`s kristalline Retinopathie
  • French: dystrophie cornéo-rétinienne cristalline de Bietti or dystrophie crystalline de Bietti
  • Italian: distrofia cristallina di Bietti
  • Turkish: Bietti nin kristalin distrofisi
  • Chinese (simplified): 结晶样视网膜色素变性, 结晶样视网膜变性, Bietti结晶营养不良
  • Chinese (traditional): 結晶樣視網膜色素變性, 結晶樣視網膜變性, Bietti結晶營養不良
  • Japanese: クリスタリン網膜症
  • Korean: 비에티 결정 이영양증 or 비에띠결정색소망막이영양증
  • Hebrew: דיסטרופית קריסטלין ע״ש בייטי
  • Arabic: الحثل البلوري لبيتي
Disclaimer: The information herein are for general information purpose only and may be inaccurate, incomplete and outdated. Nothing herein shall be construed as medical advice or diagnosis. Consult your doctor for medical advice and diagnosis.
1 NIH website
https://ghr.nlm.nih.gov/condition/bietti-crystalline-dystrophy
2 Chaker N, Mghaieth F, Baccouri R, Merdassi A, Turki F, El Matri L. (2007). Clinical and angiographic characteristics of Bietti’s corneoretinal dystrophy: a case study of an 8-year-old girl. J Fr Ophtalmol; 30(1):39-43.
3 Kobat SG, Gul FC, Yusufoglu E. (2019). Bietti crystalline dystrophy and choroidal neovascularization in childhood. Int J Ophthalmol; 12(9):1514-1516
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