Abstract
Purpose: :
To study macular structure in a patient with Bietti Crystalline Corneoretinal Dystrophy (BCCD) with high-resolution imaging.
Methods: :
Best-corrected visual acuity (VA), fundus examination, Goldmann and automated perimetry, spectral-domain optical coherence tomography (SDOCT), autofluorescence (AF), and full-field and multifocal electroretinography (ERG) were obtained. Molecular analysis of the CYP4V2 gene was performed. Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) was used to generate high resolution images of the right macula.
Results: :
A 54 year old woman with VA of 20/25 OD and 20/40 OS demonstrated fine crystals and nummular RPE atrophy in the macula with RPE mottling extending to the equator. Goldmann, automated perimetry and microperimetry demonstrated discrete dense pericentral scotomas close to fixation with preserved function at fixation and full peripheral fields. SDOCT and AF showed patchy macular RPE atrophy with crystals in all retinal layers. Scotopic and photopic ERG amplitudes were both similarly reduced by greater than 2 standard deviations below the normal mean with delayed timing. Molecular analysis demonstrated compound heterozygous mutations (c.802-8_810del17inGC; c1091-2A>G) predicted to abolish functional splice site sequences and result in skipping of exons 7 and 9 of the CYP4V2 gene, respectively. Unambiguous cones were readily observed across the 7 degree AOSLO image with normal cone spacing, although regions near the fovea corresponding to regions of RPE loss showed increased cone spacing (decreased density).
Conclusions: :
This study presents the first images of cones in a living patient with BCCD and deleterious mutations in the CPY4V2 gene. AOSLO revealed regions of cone loss near the fovea overlying RPE atrophy with otherwise normal cone spacing. Patchy cone loss interspersed with normal cone spacing suggests that BCCD may cause cone death secondary to deleterious effects associated with the crystalline deposits, rather than affecting cone survival uniformly and primarily.
Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • macula/fovea