Spectral Domain Optical Coherence Tomographic Findings of Bietti Crystalline Dystrophy

Abstract

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.

Visual Function and Central Retinal Structure in Choroideremia

“…Outer retinal tubulations have also been noted in a number of other inherited retinal degenerations, [67][68][69] but only Bietti crystalline retinopathy seems to show ORTs frequently. 70,71 Other studies have reported ORTs in CHM, 7,37,51,69,72 but the high frequency of this pathologic finding in our cohort leads to the suggestion that ORTs may be an expected part of the CHM phenotype. The presence of ORTs in patients at early ages suggests the effect is not simply a late-stage abnormality.…”

MERTK mutation update in inherited retinal diseases

“…These hyper‐reflective dots are not specific of IRD linked to MERTK mutations. They have also been reported in association with Stargardt disease (Ge et al., ), Bietti crystalline dystrophy, independently of crystal location (Saatci, Doruk, Yaman, & Oner, ), and RCD (Kuroda et al., ). In the latter, Kuroda et al.…”

Genetics of Bietti Crystalline Dystrophy

“…24,25 Optical Coherence Tomography Findings Spectral domain optical coherence tomography (SD-OCT) is able to provide detailed imaging of the retinal architectural changes in patients with BCD. [26][27][28][29][30][31] A myriad of hyperreflective spots of various configurations are present in SD-OCT sections of patients with BCD. 27,32 These multiple hyperreflective retinal dots have been observed in all retinal layers, including the inner retina and on top of the Bruch membrane.…”

“…17 Cystoid macular edema has also been observed in a few reported cases of BCD. 17,26,36 Fundus Autofluorescence Findings Fundus autofluorescence (FAF) imaging with confocal scanning laser ophthalmoscope imaging is derived from lipofuscin within the RPE, allowing noninvasive visualization of the RPE layer in BCD patients. 35 In the early stage of BCD, FAF reveals widespread hypoautofluorescence corresponding to areas of RPE atrophy and multiple hyperautofluorescent speckles in the fundus (Fig.…”

“…The positively charged R400, located in the β-strand after K helix, is considered a hotspot for gene mutations, as substitutions for C and H have been reported in this residue and they have been predicted to alter heme coordination. 10,26,57,60,62,63 In addition, the D324V substitution in the central I helix neutralizes the negative charge in this residue and will alter the local isoelectric point (pI) around the active site. Furthermore, insertion or deletion of a proline residue has been predicted to influence the stability of the protein heme coordination-dependent secondary structures, which explains why H331P (in the central I helix) and P396L (in the β-strand after K helix) are the causative mutations in BCD.…”