Detailed functional and structural phenotype of Bietti crystalline dystrophy associated with mutations in CYP4V2 complicated by choroidal neovascularization

Ophthalmic Genet. 2016 Dec;37(4):445-452. doi: 10.3109/13816810.2015.1126616. Epub 2016 Mar 30.

Abstract

Purpose: To describe in detail the phenotype of a patient with Bietti crystalline dystrophy (BCD) complicated by choroidal neovascularization (CNV) and the response to intravitreal Bevacizumab (Avastin®; Genentech/Roche).

Methods: A 34-year-old woman with BCD and mutations in CYP4V2 (c.802-8_806del13/p.H331P:c992A>C) underwent a complete ophthalmic examination, full-field flash electroretinography (ERG), kinetic and two-color dark-adapted perimetry, and dark-adaptometry. Imaging was performed with spectral domain optical coherence tomography (SD-OCT), near infrared (NIR) and short wavelength (SW) fundus autofluorescence (FAF), and fluorescein angiography (FA).

Results: Best-corrected visual acuity (BCVA) was 20/20 and 20/60 for the right and left eye, respectively. There were corneal paralimbal crystal-like deposits. Kinetic fields were normal in the peripheral extent. Retinal crystals were most obvious on NIR-reflectance and corresponded with hyperreflectivities within the RPE on SD-OCT. There was parafoveal/perifoveal hypofluorescence on SW-FAF and NIR-FAF. Rod > cone sensitivity loss surrounded fixation and extended to ~10° of eccentricity corresponding to regions of photoreceptor outer segment-retinal pigmented epithelium (RPE) interdigitation abnormalities. The outer nuclear layer was normal in thickness. Recovery of sensitivity following a ~76% rhodopsin bleach was normal. ERGs were normal. A subretinal hemorrhage in the left eye co-localized with elevation of the RPE on SD-OCT and leakage on FA, suggestive of CNV. Three monthly intravitreal injections of Bevacizumab led to restoration of BCVA to baseline (20/25).

Conclusion: crystals in BCD were predominantly located within the RPE. Photoreceptor outer segment and apical RPE abnormalities underlie the relatively extensive retinal dysfunction observed in relatively early-stage BCD. Intravitreal Bevacizumab was effective in treating CNV in this setting.

Keywords: Bietti crystalline dystrophy; CNV; CYP4V2; OCT; RPE.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Angiogenesis Inhibitors / therapeutic use
  • Bevacizumab / therapeutic use
  • Choroidal Neovascularization / diagnosis*
  • Choroidal Neovascularization / drug therapy
  • Choroidal Neovascularization / genetics
  • Corneal Dystrophies, Hereditary / diagnosis*
  • Corneal Dystrophies, Hereditary / drug therapy
  • Corneal Dystrophies, Hereditary / genetics
  • Cytochrome P450 Family 4 / genetics*
  • Electroretinography
  • Female
  • Fluorescein Angiography
  • Humans
  • Intravitreal Injections
  • Mutation*
  • Phenotype
  • Retinal Diseases / diagnosis*
  • Retinal Diseases / drug therapy
  • Retinal Diseases / genetics
  • Retinal Photoreceptor Cell Outer Segment / pathology*
  • Retinal Pigment Epithelium / pathology*
  • Tomography, Optical Coherence
  • Vascular Endothelial Growth Factor A / antagonists & inhibitors
  • Visual Acuity / physiology
  • Visual Field Tests

Substances

  • Angiogenesis Inhibitors
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • Bevacizumab
  • CYP4V2 protein, human
  • Cytochrome P450 Family 4

Supplementary concepts

  • Bietti Crystalline Dystrophy