In-Vivo Visualization of Retinal Crystals in Bietti's Crystalline Dystrophy by Spectral Domain Optical Coherence Tomography

A case of Bietti crystalline dystrophy with clinical, electrophysiological, and imaging findings

In this study, ophthalmologic examination findings, fundus fluorescein angiography, optic coherence tomography (OCT), visual field testing, electrophysiological, and systemic laboratory findings of a 43-year-old female patient who presented with blurry vision and who had retinal and corneal deposits were examined. Our patients’ best-corrected visual acuity was 0.9 bilaterally. Her anterior segments and intraocular pressures were bilaterally normal. Fundus examination revealed bilateral glistening yellowish intraretinal crystalline deposits in the posterior pole and midperipheral retina. The electroretinographic examination revealed a decrease in scotopic and photopic a and b wave amplitudes. Corneal and intraretinal glistening crystalloid deposits were observed in the OCT. Our patient and her husband were relatives. Her sister’s, brother’s, and children’s OCT also revealed bilateral corneal and intraretinal crystalloid deposits. We diagnosed this case as Bietti’s crystalline dystrophy which is a rare disease with genetic inheritance that must be considered in the differential diagnosis in countries in which consanguineous marriage is often.

Optical coherence tomography and optical coherence tomography angiography imaging in Bietti crystalline dystrophy

Background: Bietti crystalline dystrophy (BCD) is a rare autosomal recessive disorder due to genetic defect in the CYP4V2 gene. BCD is a disease characterized by shiny yellow crystalline deposits in the retina with progressive atrophy of the retinal pigment epithelium and choriocapillaris. Our aim is to present ocular imaging findings of a patient with BCD.Materials and Metods: A 38-year-old female patient with BCD was evaluated and the findings of optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) were examined.Results: OCT imaging revealed multiple outer retinal tubulations (ORTs) with a few hyperreflective crystalline deposits. OCTA imaging showed that the vessel density of superficial anddeep capillary plexus and choriocapillaris blood flow were significantly decreased. ORTs were composedof multiple microtubules as finger-like protrusions that joined the macrotubules.Conclusion: In BCD, crystallinedeposits, ORTs and retinal vascular morphology can be shown in detail using OCT and OCTA.

Spectral domain optical coherence tomographic findings of bietti crystalline dystrophy

We analyzed the OCT features of 24 eyes of 12 patients with Bietti crystalline dystrophy (BCD) with the Heidelberg HRA2-OCT. Seventeen of 24 eyes were in intermediate stage of the disease and seven in advanced stage of the disease at the time of latest OCT examination performed in 2014. Outer retinal tubulations and retinal hyperreflective dots were present in 20 of 24 eyes. The remaining four eyes had advanced disease with very thin retina. Appearance of bright plaque on top of RPE-Bruch membrane was present in all eyes. Choroidal hyperreflective spots were noted in 19 of 24 eyes. The remaining five eyes had advanced disease stage with very thin choroid. Mean central macular thickness was 163.08 μm ± 62.52 for all eyes (170.35 μm ± 56.46 in eyes with intermediate disease and 145.42 μm ± 77.2 in eyes with advanced disease). Mean subfoveal choroidal thickness was 95.37 μm ± 55.93 for the study eyes (116.47 ± 46.92 μm in eyes with intermediate disease and 44.14 μm ± 42.43 in eyes with advanced disease). Choroidal hyperreflective spots were noted in 21 of 24 eyes (87.5%). SD-OCT shows the disease progression in retinal and choroidal layers delicately in eyes with BCD and expands our knowledge about the ongoing disease process.

Bietti crystalline dystrophy: a morpho-functional evaluation

We report the clinical findings and macular function of a patient with Bietti crystalline dystrophy. A 39-year-old woman reported visual loss in both eyes and nyctalopia. A complete ophthalmological evaluation, retromode imaging, SD-OCT acquisition, MP1 microperimetry, and multifocal electroretinogram (mfERG) were performed. Microcrystalline deposits in the cornea and the retina with retinal pigment epithelial atrophy were observed. Retromode imaging revealed visualization of normal large choroidal vessels, cystoid macular edema, and small defined glistening lesions. SD-OCT showed changes in the outer retina with numerous microcrystalline deposits. Microperimetry showed an absolute scotoma involving the perimacular area but sparing of the fovea. In both eyes, mfERG analysis suggests a dysfunction of pre-ganglionic retinal elements detectable in the 20 central retinal degrees. The genetic characterization showed an homozygous mutation c.772C > T[p.Leu258Phe] in exon 6. Retromode imaging and SD-OCT were useful tools to determine the extent and the localization of the crystals. Microperimetry should allow evaluation of the progression of the macular changes.