A great diversity of ROBO4 expression and regulations identified by data mining and transgene mice.

ROBO4 involves in the stabilization of blood vessel and mediates the migration of hematopoietic stem cell and newborn neuron. However, the patterns of expression and regulation are not quite clear. To resolve this, we analyzed the single cell sequence data, and confirmed that Robo4 mainly expresses in various endothelial cells, but also in epithelial cells, pericytes, and stem or progenitor cells of bone marrow, fibroblast cells/mesenchymal stem cell of adipose tissues, muscle cells and neuron. Robo4 expressions in endothelial cells derived from capillary vessel, tip/stalk/activated endothelial cells were higher than that in artery and large vein (matured endothelial cells). On the other hand, via mining the gene expression data deposited in the NCBI Gene Expression Omnibus database as well as National Genomics Data Center (NGDC), we uncovered that the expression of Robo4 were regulated by different stimulus and variable in diseases' condition.Moreover, we constructed enhanced GFP (eGFP) transgene mouse controlled by Robo4 promoter using CRISPR/CAS9 system. We found GFP signals in many cell types from the embryonic section, confirming a widely expression of Robo4. Together, Robo4 widely and dynamically express in multiple cell types, and can be regulated by diverse factors.

Repeatability, interocular correlation and agreement of optic nerve head vessel density in healthy eyes: a swept-source optical coherence tomographic angiography study.

AIM: To assess the repeatability, interocular correlation, and agreement of quantitative swept-source optical coherence tomography angiography (OCTA) optic nerve head (ONH) parameters in healthy subjects. METHODS: Thirty-three healthy subjects were enrolled. The ONH of both eyes were imaged four times by a swept-source-OCTA using a 3 mm ×3 mm scanning protocol. Images of the radial peripapillary capillary were analyzed by a customized Matlab program, and the vessel density, fractal dimension, and vessel diameter index were measured. The repeatability of the four scans was determined by the intraclass correlation coefficient (ICC). The most well-centered optic disc from the four repeated scans was then selected for the interocular correlation and agreement analysis using the Pearson correlation coefficient, ICC and Bland-Altman plots. RESULTS: All swept-source-OCTA ONH parameters exhibited certain repeatability, with ICC>0.760 and coefficient of variation (CoV)≤7.301%. The obvious interocular correlation was observed for papillary vessel density (ICC=0.857), vessel diameter index (ICC=0.857) and fractal dimension (ICC=0.906), while circumpapillary vessel density exhibited moderate interocular correlation (ICC=0.687). Bland-Altman plots revealed an agreement range of -5.26% to 6.21% for circumpapillary vessel density. CONCLUSION: OCTA ONH parameters demonstrate good repeatability in healthy subjects. The interocular correlations of papillary vessel density, fractal dimension and vessel diameter index are high, but the correlation for circumpapillary vessel density is moderate.

Inter-Individual Topographic Variation of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography.

Purpose: To investigate the topographic characters of inter-individual variations of the macular choroidal thickness (CT). Methods: This was a retrospective study. Macular CT data for 900 0.2 × 0.2-mm grids from 410 healthy eyes were collected from swept-source optical coherence tomography. Following the analysis of factors associated with mean CT, the ß-coefficients of the included associated factors in each grid were summarized for choroidal thickness changes analysis. Additionally, the coefficient of variance (CoV), coefficient of determination (CoD), and coefficient of variance unexplained (CoVU) for CT were calculated in each individual grid to investigate the inter-individual choroidal variations pattern. Results: Sex (ß = -17.26, female vs. male), age (ß = -1.61, per 1 year), and axial length (ß = -18.62, per 1 mm) were associated with mean macular CT. Females had a thinner choroid in all 900 grids (0.5-26.9 µm). As age increased, the CT noticeably decreased (8.74-19.87 µm per 10 years) in the temporal regions. With axial length elongation, the thinning (7.94-24.91 µm per 1 mm) was more evident in subfoveal and nasal regions. Both the CoV (34.69%-58.00%) and CoVU (23.05%-40.78%) were lower in the temporal regions, whereas the CoD (18.41%-39.66%) was higher in the temporal regions. Conclusions: Choroidal thinning is more predominant in the subfoveal and nasal regions with axial length elongation, but in the temporal region with aging. The inter-individual variation of CT is higher and less determined by sex, age, or axial length in the nasal regions. Translational Relevance: Topographic variation should be considered when interpreting choroidal thickness.

Research Trends and Hotspots of Retinal Optical Coherence Tomography: A 31-Year Bibliometric Analysis.

The emergence of optical coherence tomography (OCT) over the past three decades has sparked great interest in retinal research. However, a comprehensive analysis of the trends and hotspots in retinal OCT research is currently lacking. We searched the publications on retinal OCT in the Web of Science database from 1991 to 2021 and performed the co-occurrence keyword analysis and co-cited reference network using bibliometric tools. A total of 25,175 publications were included. There has been a progressive increase in the number of publications. The keyword co-occurrence network revealed five clusters of hotspots: (1) thickness measurements; (2) therapies for macular degeneration and macular edema; (3) degenerative retinal diseases; (4) OCT angiography (OCTA); and (5) vitrectomy for macular hole and epiretinal membrane. The co-citation analysis displayed 26 highly credible clusters (S = 0.9387) with a well-structured network (Q = 0.879). The major trends of research were: (1) thickness measurements; (2) therapies for macular degeneration and macular edema; and (3) OCTA. Recent emerging frontiers showed a growing interest in OCTA, vessel density, choriocapillaris, central serous chorioretinopathy, Alzheimer's disease, and deep learning. This review summarized 31 years of retinal OCT research, shedding light on the hotspots, main themes, and emerging frontiers to assist in future research.

Application of Optical Coherence Tomography to a Mouse Model of Retinopathy.

Optical coherence tomography (OCT) offers a noninvasive method for the diagnosis of retinopathy. The OCT machine can capture retinal crosssectional images from which the retinal thickness can be calculated. Although OCT is widely used in clinical practice, its application in basic research is not as prevalent, especially in small animals such as mice. Because of the small size of their eyeballs, it is challenging to conduct fundus imaging examinations in mice. Therefore, a specialized retinal imaging system is required to accommodate OCT imaging on small animals. This article demonstrates a small-animal-specific system for OCT examination procedures and a detailed method for image analysis. The results of retinal OCT examination of very-low-density lipoprotein receptor (Vldlr) knockout mice and C57BL/6J mice are presented. The OCT images of C57BL/6J mice showed retinal layers, while those of Vldlr knockout mice showed subretinal neovascularization and retinal thinning. In summary, OCT examination could facilitate the noninvasive detection and measurement of retinopathy in mouse models.

Correlation Between Electroretinogram and Visual Prognosis in Metallic Intraocular Foreign Body Injury.

Purpose: This study aims to investigate the correlation between electroretinogram (ERG) and visual outcome in eyes with metallic intraocular foreign body (IOFB) injury. Methods: Cases with metallic IOFB injuries with preoperative ERG from January 2008 to May 2020 were reviewed retrospectively. Five ERG responses were recorded, including rod response, maximal response, oscillatory potentials, cone response, and 30-Hz flicker. The results were compared between the affected and the contralateral eyes. All patients received surgery to remove IOFBs. The correlation between amplitudes, implicit times, and grades of ERG with final best-corrected visual acuity (BCVA) was analyzed. Results: A total of 33 eyes of 33 patients were included. The eyes with IOFB had generally delayed implicit time and reduced amplitude in all waves. The maximum change was found in oscillatory potentials S3 and N1 (0.42 ± 0.42 and 1.95 ± 1.97 of the fellow eyes, respectively, p < 0.05). All amplitudes were negatively correlated with the final BCVA (rs: -0.676 to -0.459, all p < 0.05). In contrast, all implicit times were positively correlated with final BCVA, although, some of them were not statistically significant (rs: 0.035 to 0.687). Among them, oscillatory potential P3 has the highest correlation coefficient (rs = 0.687, p < 0.001). All grades of ERG waves were statistically correlated with the final BCVA (rs: -0.596 to -0.664, all p < 0.001). Conclusions: ERG can be used to assess visual outcome in metallic IOFB injury after surgery. Oscillatory potentials provided the most significant responses.

Whole exome sequencing reveals novel EYS mutations in Chinese patients with autosomal recessive retinitis pigmentosa.

Purpose: Retinitis pigmentosa (RP) belongs to a group of inherited retinal diseases with high genetic heterogeneity. This study aimed at identifying the disease-causing variants in patients with autosomal recessive RP. Methods: Three RP families with autosomal recessive inheritance and 139 sporadic RP patients were included. Complete ophthalmic examinations were conducted in all the study subjects. DNA samples were extracted from patients' peripheral blood for whole exome sequencing (WES) analysis. Direct Sanger sequencing was conducted for validating the identified mutations and cosegregation pattern in the RP families. Results: One novel (c.7492G>C:p.Ala2498Pro and c.8422C>T:p.Ala2808Thr) and one reported (c.8012T>A:p.Leu2671X and 6416G>A:p.Cys2139Tyr) pair of compound heterozygous mutations, as well as one reported compound homozygous mutation (c.6416G>A:p.Cys2139Tyr/c.8012T>A:p.Leu2671X), were identified in the EYS gene from three families with autosomal recessive RP. All the mutations were cosegregated with the RP phenotype in the RP families. For the sporadic RP patients, seven novel and seven reported EYS variants were identified in 19 patients, including two novel frameshift (c.8301dupT:p.Asp2767fs and c.9437_9440del:p.Glu3146fs), three novel missense (c.8297G>C:p.Gly2766Ala, c.9052T>C:p.Trp3018Arg, and c.8907T>G:p.Cys2969Trp), and one nonsense (c.490C>T:p.Arg164X) variants. All the novel mutations were confirmed by Sanger sequencing. Most of the variants were located at the C-terminus of the EYS protein. Bioinformatics analyses indicated that all detected variants were damaging or possibly damaging. Conclusions: This study identified eight novel EYS variants and expanded the spectrum of EYS mutations in Chinese RP patients.