Yukiko Makiyama

Comprehensive Molecular Diagnosis of a Large Cohort of Japanese Retinitis Pigmentosa and Usher Syndrome Patients by Next-Generation Sequencing

PURPOSE Retinitis pigmentosa (RP), a major cause of blindness in developed countries, has multiple causative genes; its prevalence differs by ethnicity. Usher syndrome is the most common form of syndromic RP and is accompanied by hearing impairment. Although molecular diagnosis is challenging, recent technological advances such as targeted high-throughput resequencing are efficient screening tools. METHODS We performed comprehensive molecular testing in 329 Japanese RP and Usher syndrome patients by using a custom capture panel that covered the coding exons and exon/intron boundaries of all 193 known inherited eye disease genes combined with Illumina HiSequation 2500. Candidate variants were screened using systematic data analyses, and their potential pathogenicity was assessed according to the frequency of the variants in normal populations, in silico prediction tools, and compatibility with known phenotypes or inheritance patterns. RESULTS Molecular diagnoses were made in 115/317 RP patients (36.3%) and 6/12 Usher syndrome patients (50%). We identified 104 distinct mutations, including 66 novel mutations. EYS, USH2A, and RHO were common causative genes. In particular, mutations in EYS accounted for 15.0% of the autosomal recessive/simplex RP patients or 10.7% of the entire RP cohort. Among the 189 previously reported mutations detected in the current study, 55 (29.1%) were found commonly in Japanese or other public databases and were excluded from molecular diagnoses. CONCLUSIONS By screening a large cohort of patients, this study catalogued the genetic variations involved in RP and Usher syndrome in a Japanese population and highlighted the different distribution of causative genes among populations.

Wide-Field Fundus Autofluorescence Imaging of Retinitis Pigmentosa

PURPOSE To evaluate the clinical usefulness of wide-field fundus autofluorescence (FAF) imaging in patients with retinitis pigmentosa (RP). DESIGN Cross-sectional case series. PARTICIPANTS Seventy-five eyes of 75 patients with RP. METHODS We examined the eyes of the RP patients using the Optos 200Tx imaging system (Optos PLC, Dunfermline, United Kingdom) and identified abnormal FAF patterns such as ring hyperautofluorescence and patchy hypoautofluorescent areas. Patients with hyperautofluorescent rings or foveal hyperautofluorescence were compared with those without such findings. We determined the percentage area occupied by the FAF abnormalities within a defined region of the eye and examined the relationship between the percentage area of these abnormalities and the visual field area. Moreover, we categorized the patients into 3 different groups based on the presence of a patchy hypoautofluorescent lesion larger than 1 disc diameter: Group A consisted of those with patchy lesions smaller than 1 disc diameter, group B consisted of those with patchy lesions larger than 1 disc diameter but present in only 1 quadrant, and group C consisted of those with patchy lesions larger than 1 disc diameter and present in more than 1 quadrant. In addition, various clinical characteristics were compared among these 3 groups. MAIN OUTCOME MEASURES Predicting the visual field size and duration of the disease in RP patients based on FAF patterns. RESULTS Patients without hyperautofluorescent rings or foveal hyperautofluorescence had better visual acuity or mean deviation measured with a Humphrey perimeter. The total area of the abnormal FAF image correlated with the visual field area measured with a Goldmann perimeter (R = -0.64, P<0.001). The individuals with the large patchy hypofluorescent areas (i.e., larger than 1 disc diameter) were older than those with small patchy hypofluorescent areas (group A vs. groups B and C, P = 0.002 and P<0.001, respectively) and had experienced the symptoms for longer durations (group A vs. groups B and C, P<0.05 and P<0.001, respectively). CONCLUSIONS We can estimate the visual field in patients with RP using the objective measurements from wide-field FAF. The presence of patchy hypofluorescent lesions can be used an indicator of the duration of RP. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Granulocyte colony-stimulating factor attenuates oxidative stress-induced apoptosis in vascular endothelial cells and exhibits functional and morphologic protective effect in oxygen-induced retinopathy

Granulocyte colony-stimulating factor (G-CSF) is a known hematopoietic glycoprotein, and recent studies have revealed that G-CSF possesses other interesting properties. Oxidative stress is involved in many diseases, such as atherosclerosis, heart failure, myocardial infarction, Alzheimer disease, and diabetic retinopathy. This study was designed to examine whether G-CSF has a protective effect on endothelial cells against oxidative stress and to investigate whether G-CSF has a therapeutic role in ischemic vascular diseases. Expression of G-CSF (P < .01) and G-CSF receptor (P < .05) mRNA in human retinal endothelial cells (HRECs) was significantly up-regulated by oxidative stress. Treatment with 100 ng/mL G-CSF significantly reduced H(2)O(2)-induced apoptosis in HRECs from 61.7% to 41.4% (P < .05). Akt was phosphorylated in HRECs by G-CSF addition, and LY294002, a PI3K inhibitor, significantly attenuated the antiapoptotic effect of G-CSF (by 44.1%, P < .05). The rescue effect was also observed in human umbilical vein endothelial cells. In mouse oxygen-induced retinopathy model, G-CSF significantly reduced vascular obliteration (P < .01) and neovascular tuft formation (P < .01). G-CSF treatment also clearly rescued the functional and morphologic deterioration of the neural retina. A possibility of a novel therapeutic strategy for ischemic diseases through attenuating vascular regression using G-CSF was proposed.

Knockout of ccr2 alleviates photoreceptor cell death in a model of retinitis pigmentosa.

Neuroinflammation involving CC chemokines such as monocyte chemoattractant protein-1 (MCP-1) has been demonstrated in the pathological process of retinitis pigmentosa (RP), an inherited degenerative retinal disease. However, the mechanism of MCP-1 and its receptor CCR2 involvement in the disease remains unclear. To investigate the role of MCP1/CCR2 in RP pathogenesis, ccr2 mutant RP mice (ccr2(-/-) rd10) were created and analyzed. The expression of MCP-1, RANTES, stromal cell-derived factor (SDF-1), and tumor necrosis factor-α (TNF-α) in the retinas of wild-type, rd10, and ccr2(-/-) rd10 mice was analyzed using quantitative RT-PCR. Photoreceptor apoptosis (TUNEL staining) and the number of microglia (positive for the F4/80 antibody) in the retina were examined. Retinal function was assessed using electroretinograms, and the structure of the whole retina was analyzed from images obtained using optical coherence tomography (OCT) and by histological examination. The expression levels of MCP-1, RANTES, and SDF-1 increased with time in the rd10 mice but not in the wild-type mice. Rearing the mice in the dark prevented degeneration and resulted in thicker photoreceptor layers at each time point. In those mice, the peaks of chemokine expression shifted to a later time with degeneration, suggesting that the expression of these chemokines was induced during the progression of degeneration. Although the difference was not so obvious, the retina in the ccr2(-/-) rd10 mice was consistently and significantly thicker than that in the rd10 (ccr2(+/+) rd10) mice at all time points. Rhodopsin gene expression was also higher in the ccr2(-/-) rd10 mice than in rd10 (ccr2(+/+) rd10) mice, suggesting photoreceptor survival in the former. Retinal function was also better preserved in the ccr2(-/-) rd10 mice than in the rd10 mice. The number of microglia in the retinas of the ccr2(-/-) rd10 mice was significantly lower than that in the retinas of the rd10 mice. Interestingly, the MCP-1 induction that was observed in the retinas of the rd10 mice was diminished in the retinas of the ccr2(-/-) rd10 mice. Our results suggest that the MCP-1/CCR2 system plays a role in retinal degeneration in rd mouse retinas. Retinal MCP-1 expression in the rd mouse retina may be partially controlled by ccr2-positive circulating cells.

Outer retinal circular structures in patients with Bietti crystalline retinopathy

Background Bietti crystalline retinopathy (BCR) is a distinct retinal degenerative disease characterised by retinal degeneration with many yellow–white crystals located mainly at the posterior pole area. Using spectral domain-optical coherence tomography (SD-OCT), the structural change in retina was investigated. Methods Patients diagnosed with BCR (n=12), retinitis pigmentosa (RP, n=292) and cone dystrophy (n=16) were included in this study. The authors mainly examined fundus photographs and SD-OCT, infrared and fundus autofluorescence images of these patients. Results Crystalline deposits were detected in portions of the retinal pigment epithelium that lacked patchy degenerated lesions. SD-OCT revealed that most of the observed crystalline deposits were located adjacent to the inner side of retinal pigment epithelium layer. The change most frequently observed was circular hyper-refractive structures in the outer nuclear layer. Although the structures were considered to be previously reported “tubular formation” or “tubular degeneration”, we determined that many of these circular structures were slices of spherical structures and were typically noted in areas suspected of ongoing active degeneration. Conclusion BCR has characteristic structures in the outer nuclear layer. Although the incidence of the structure varies, it may be characteristic of retinal degeneration and can be found in many retinal degenerative diseases.

Macular Cone Abnormalities in Retinitis Pigmentosa with Preserved Central Vision Using Adaptive Optics Scanning Laser Ophthalmoscopy

Purpose To assess macular photoreceptor abnormalities in eyes with retinitis pigmentosa (RP) with preserved central vision using adaptive optics scanning laser ophthalmoscopy (AO-SLO). Methods Fourteen eyes of 14 patients with RP (best-corrected visual acuity 20/20 or better) and 12 eyes of 12 volunteers underwent a full ophthalmologic examination, fundus autofluorescence, spectral-domain optical coherence tomography (SD-OCT), and imaging with a prototype AO-SLO system. Cone density and spatial organization of the cone mosaic were assessed using AO-SLO images. Results In 3 eyes with RP and preserved central vision, cones formed a mostly regular mosaic pattern with small patchy dark areas, and in 10 eyes, the cone mosaic patterns were less regular, and large dark regions with missing cones were apparent. Only one eye with RP demonstrated a normal, regular cone mosaic pattern. In eyes with RP, cone density was significantly lower at 0.5 mm and 1.0 mm from the center of the fovea compared to normal eyes (P<0.001 and 0.021, respectively). At 0.5 mm and 1.0 mm from the center of the fovea, a decreased number of cones had 6 neighbors in eyes with RP (P = 0.002 for both). Greater decrease in cone density was related to disruption of the photoreceptor inner segment (IS) ellipsoid band on SD-OCT images (P = 0.044); however, dark regions were seen on AO-SLO even in areas of continuous IS ellipsoid on SD-OCT. Decreased cone density correlated thinner outer nuclear layer (P = 0.029) and thinner inner segment and outer segment thickness (P = 0.011) on SD-OCT. Conclusions Cone density is decreased and the regularity of the cone mosaic spatial arrangement is disrupted in eyes with RP, even when visual acuity and foveal sensitivity are good. AO-SLO imaging is a sensitive quantitative tool for detecting photoreceptor abnormalities in eyes with RP.

Prevalence and spatial distribution of cystoid spaces in retinitis pigmentosa: investigation with spectral domain optical coherence tomography.

Purpose: To investigate the prevalence and spatial distribution of cystoid spaces (CS) in retinitis pigmentosa patients with spectral domain optical coherence tomography. Methods: A total of 529 eyes of 275 patients with retinitis pigmentosa were examined with spectral domain optical coherence tomography. The presence or absence of CS was judged for each eye. Retinal layer and outer retinal status where the CS existed were also investigated. Statistical analysis was performed using 1 eye per 1 patient. Results: Cystoid spaces were present in 119 of 529 eyes (22.5%) of 74 of 275 patients (26.9%). There were no significant differences between the cases with and without CS except for central foveal thickness (P < 0.001). Cystoid spaces were noted in the inner nuclear layer in almost all eyes (98.6%), and outer nuclear layer/outer plexiform layer was also involved in many eyes (27.8%). Cystoid spaces were sometimes seen in ganglion cell layer (6.9%). Cystoid spaces were predominantly (78.9%) distributed in the relatively preserved retina where external limiting membrane was retained. The presence of epiretinal membrane or posterior vitreous adhesion was associated with the presence of CS (P < 0.001) but showed no relationship with the spatial location of CS (P = 1.000). Conclusion: The prevalence of CS in patients with retinitis pigmentosa was 26.9% and contrary to previous reports, most CS were present in inner nuclear layer. In addition, most CS were observed in relatively retained retina, which is compatible to the prevailing notion. Epiretinal membrane or posterior vitreous adhesion was also associated with the development of CS. The distribution of CS in inner and preserved retina may provide insight for the pathogenesis of CS in retinitis pigmentosa.

Retinal microstructural changes in eyes with resolved branch retinal vein occlusion: an adaptive optics scanning laser ophthalmoscopy study.

PURPOSE To assess macular photoreceptor abnormalities in eyes with resolved branch retinal vein occlusion (BRVO) using adaptive optics scanning laser ophthalmoscopy (AO-SLO). DESIGN Prospective observational cross-sectional case series. METHODS After complete resolution of macular edema and retinal hemorrhage, 21 eyes (21 patients) with BRVO underwent full ophthalmologic examination and imaging with optical coherence tomography (OCT) and a prototype AO-SLO system. Cone density and spatial mosaic organization were assessed using AO-SLO images. RESULTS Regular parafoveal cone mosaic patterns were clearly visualized with the prototype AO-SLO imaging system in the BRVO-unaffected side. However, in the side of the retina previously affected by the BRVO, cone mosaic patterns were disorganized and dark regions missing wave-guiding cones were apparent. Additionally, retinal capillaries were dilated, no longer had a uniform caliber, and had less direct paths through the retina. In the affected side, parafoveal cone density was significantly decreased, compared with the corresponding retinal area on the unaffected side (P < .001). Furthermore, the hexagonal Voronoi domain ratio and the nearest-neighbor distances were significantly lower than in the unaffected side (P < .05). These parameters were also correlated with photoreceptor layer integrity in the parafovea. CONCLUSIONS After BRVO-associated retinal hemorrhage and macular edema resolved, affected parafoveal cone density decreases and the cone mosaic spatial arrangement is disrupted, becoming more irregular. These cone microstructural abnormalities may extend to parafovea in the BRVO-unaffected side.

Wide-Field Fundus Autofluorescence Abnormalities and Visual Function in Patients With Cone and Cone-Rod Dystrophies

PURPOSE To evaluate the clinical utility of wide-field fundus autofluorescence (FAF) in patients with cone dystrophy and cone-rod dystrophy. METHODS Sixteen patients with cone dystrophy (CD) and 41 patients with cone-rod dystrophy (CRD) were recruited at one institution. The right eye of each patient was included for analysis. We obtained wide-field FAF images using a ultra-widefield retinal imaging device and measured the area of abnormal FAF. The association between the area of abnormal FAF and the results of visual acuity measurements, kinetic perimetry, and electroretinography (ERG) were investigated. RESULTS The mean age of the participants was 51.4 ± 17.4 years, and the mean logarithm of the minimum angle of resolution was 1.00 ± 0.57. The area of abnormal FAF correlated with the scotoma measured by the Goldman perimetry I/4e isopter (ρ = 0.79, P < 0.001). The area also correlated with amplitudes of the rod ERG (ρ = -0.63, P < 0.001), combined ERG a-wave (ρ = -0.72, P < 0.001), combined ERG b-wave (ρ = -0.66, P < 0.001), cone ERG (ρ = -0.44, P = 0.001), and flicker ERG (ρ = -0.47, P < 0.001). CONCLUSIONS The extent of abnormal FAF reflects the severity of functional impairment in patients with cone-dominant retinal dystrophies. Fundus autofluorescence measurements are useful for predicting retinal function in these patients.

Cone Abnormalities in Fundus Albipunctatus Associated With RDH5 Mutations Assessed Using Adaptive Optics Scanning Laser Ophthalmoscopy

PURPOSE To assess macular photoreceptor abnormalities in eyes with fundus albipunctatus with RDH5 mutation by using adaptive optics scanning laser ophthalmoscopy (AO-SLO). DESIGN Prospective cross-sectional study. METHODS Ten eyes with fundus albipunctatus and 11 normal eyes underwent a full ophthalmologic examination, microperimetry, spectral-domain optical coherence tomography (SD OCT), and imaging with a prototype AO-SLO system. Cone density and spatial organization of the cone mosaic were assessed using AO-SLO images. Statistical analysis was done using data from right eyes of all patients. RESULTS Four patients had the same mutation in RDH5 (c.928delC/insGAAG), and 1 patient had a novel mutation in RDH5 (c.718delG). AO-SLO revealed the presence of small patchy dark areas representing cone loss in the macula of all eyes with fundus albipunctatus, including eyes for which fundus photographs showed no macular abnormalities and SD OCT did not reveal any visible defects in the photoreceptor layer. Compared to normal eyes, eyes with fundus albipunctatus demonstrated significantly lower cone density in areas at 0.5 mm from the center of the fovea (P = .020). At 0.5 mm and 1.0 mm from the center of the fovea, eyes with fundus albipunctatus showed fewer cones with 6 neighbors (P = .041 and P = .006). AO-SLO revealed hyperreflective mosaics surrounded by hyporeflective rings in areas corresponding to the retinal flecks. CONCLUSIONS Macular cone density is lower and the regularity of the macular cone mosaic spatial arrangement is disrupted in eyes with fundus albipunctatus. AO-SLO imaging is a sensitive quantitative tool for detecting photoreceptor abnormalities in eyes with fundus albipunctatus.