Exosomal lncRNA-MIAT promotes neovascularization via the miR-133a-3p/MMP-X1 axis in diabetic retinopathy.

Diabetic retinopathy (DR), a most common microangiopathy of diabetes, causes vision loss and even blindness. The mechanisms of exosomal lncRNA remain unclear in the development of DR. Here, we first identifed the pro-angiogenic effect of exosomes derived from vitreous humor of proliferative diabetic retinopathy patients, where lncRNA-MIAT was enriched inside. Secondly, lncRNA-MIAT was demonstrated significantly increased in exosomes from high glucose induced human retinal vascular endothelial cell, and can regulate tube formation, migration and proliferation ability to promote angiogenesis in vitro and in vivo. Mechanistically, the pro-angiogenic effect of lncRNA-MIAT was via the lncRNA-MIAT/miR-133a-3p/MMP-X1 axis. The reduced level of lncRNA-MIAT in this axis mitigated the generation of retinal neovascular in mouse model of oxygen-induced retinopathy (OIR), providing crucial evidence for lncRNA-MIAT as a potential clinical target. These findings enhance our understanding of the role of exosomal lncRNA-MIAT in retinal angiogenesis, and propose a promising therapeutic strategy against diabetic retinopathy.

Human lens epithelial-secreted exosomes attenuate ocular angiogenesis via inhibiting microglial activation.

The lens is an avascular tissue, where epithelial cells (LECs) are the primary living cells. The role of LECs-derived exosomes (LEC-exos) is largely unknown. In our study, we determined the anti-angiogenic role of LEC-exos, manifested as regressed retinal neovascularization (NV) using the oxygen-induced retinopathy (OIR), and reduced choroidal NV size and pathological vascular leakage using the laser-induced choroidal neovascularization (laser-induced CNV). Furthermore, the activation and accumulation of microglia were also restricted by LEC-exos. Based on Luminex multiplex assays, the expressions of chemokines such as SCYB16/CXCL16, MCP-1/CCL2, I-TAC/CXCL11, and MIP 3beta/CCL19 were decreased after treatment with LEC-exos. Transwell assays showed that LEC-exos restricted the migration of the mouse microglia cell line (BV2 cells). After incubation with LEC-exos-treated BV2 cells, human umbilical vein endothelial cells (hUVECs) were collected for further evaluation using tube formation, Transwell assays, and 5-ethynyl-2'-deoxyuridine (EDU) assays. Using in vitro experiments, the pro-angiogenic effect of microglia was restricted by LEC-exos. Hence, it was investigated that LEC-exos attenuated ocular NV, which might attribute to the inhibition of microglial activation and accumulation.

Lens epithelial cell-derived exosome inhibits angiogenesis in ocular pathological neovascularization through its delivery of miR-146a-5p.

Abnormal ocular neovascularization, a major pathology of eye diseases, leads to severe visual loss. The role of lens epithelial cell (LEC)-derived exosomes (Lec-exo) is largely unknown. Thus, we aimed to investigate whether Lec-exo can inhibit abnormal ocular neovascularization and explore the possible mechanisms. In our study, we proved the first evidence that exosomes derived from LECs attenuated angiogenesis in both oxygen-induced retinopathy and laser-induced choroidal neovascularization mice models. Further in vitro experiments proved that Lec-exo inhibited proliferation, migration, and tube formation capability of human umbilical vein endothelial cells in high glucose condition. Further high-throughput miRNAs sequencing analysis detected that miR-146a-5p was enriched in Lec-exo. Mechanistically, exosomal miR-146a-5p was delivered to endothelial cells and bound to the NRAS coding sequence, which subsequently inactivated AKT/ERK signaling pathway. We successfully elucidated the function of Lec-exo in inhibiting abnormal ocular neovascularization, which may offer a promising strategy for treatment of abnormal ocular neovascularization.

M2 microglia-derived exosomes promote vascular remodeling in diabetic retinopathy.

Diabetic retinopathy (DR) is a vision-threatening diabetic complication that is characterized by microvasculature impairment and immune dysfunction. The present study demonstrated that M2 microglia intensively participated in retinal microangiopathy in human diabetic proliferative membranes, mice retinas, retinas of mice with oxygen-induced retinopathy (OIR) mice, and retinas of streptozotocin-induced DR mice. Further in vivo and in vitro experiments showed that exosomes derived from M2 polarized microglia (M2-exo) could reduce pericyte apoptosis and promote endothelial cell proliferation, thereby promoting vascular remodeling and reducing vascular leakage from the diabetic retina. These effects were further enhanced by M2-exo that facilitated M2 polarization of retinal microglia. Collectively, the study demonstrated the capability of M2-exo to induce retinal microvascular remodeling, which may provide a new therapeutic strategy for the treatment of DR.

Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia.

PURPOSE: To propose an ultrathin biological amniotic membrane (btAM) thinner than 10 µm as the graft to treat highly myopic macular holes (MH). METHODS: This pilot study included 14 patients affected by refractory macular holes associated with high myopia. btAM was used as a bandage covering the holes. The best-corrected visual acuity (BCVA), fundus photography, and optical coherence tomography (OCT) before and after surgery were compared. RESULTS: The mean MH size was 865.93 ± 371.72 µm and all the MHs achieved anatomical closure. The btAM located centrally and fully on MHs from fundus photography yet no obvious visual masking was complained. The average BCVA 1 month, 3, and 6 months after surgery were 0.95 ± 0.24, 0.92 ± 0.23, 0.92 ± 0.23 logMAR, respectively, improved significantly compared to pre-operative BCVA (1.24 ± 0.42 logMAR, all P < 0.05). Ten out of 14 (71.4%) exhibited 2C closure patterns (formally closed and no bare RPE) on OCT. CONCLUSION: The btAM thinner showed a favorable anatomical success with less risk of parafoveal atrophy or iatrogenic injuries and shortened the dissolving time.

Local-flexible coupling optical-resolution photoacoustic microscopy with enhanced sensitivity.

An acoustic coupling scheme largely determines the performance of optical-resolution photoacoustic microscopy (OR-PAM), including practicability, sensitivity, and stability. In this study, we propose OR-PAM based on a local-flexible acoustic coupling scheme, which includes a well-designed combiner connecting a set of circulating systems. The combiner integrates an objective lens and an ultrasonic transducer, controls the water level, restricts the flow rate, and drains bubbles. The circulating system provides sustained and steady flowing water. The flowing water constrained in the combiner and the circulating system forms a flexible and stable local contact between the sample and the transducer. Phantom experiments demonstrate that the proposed method can maintain high optical resolution but improve the detection sensitivity by approximately 1.9 times in comparison to dry coupling. In vivo imaging experiments of the mouse eyeground are conducted to examine the practicability of the proposed system in biomedicine. Moreover, in vivo experiments show that OR-PAM based on local-flexible coupling can reveal more details of eyeground microvasculatures, benefiting from its enhanced sensitivity. These merits promise that OR-PAM based on local-flexible coupling may have broad applications in biomedical fields.

PERFLUOROCARBON LIQUID-ASSISTED INVERTED INTERNAL LIMITING MEMBRANE FLAP TECHNIQUE VERSUS INTERNAL LIMITING MEMBRANE PEELING FOR HIGHLY MYOPIC MACULAR HOLE RETINAL DETACHMENT.

PURPOSE: To compare the efficacy of a modified perfluorocarbon liquid-assisted inverted internal limiting membrane (ILM) flap technique with the standard ILM peeling for the treatment of macular hole retinal detachment in highly myopic eyes. METHODS: This was a retrospective, consecutive, nonrandomized comparative study. Forty-two macular hole retinal detachment eyes of 42 patients were included into either a perfluorocarbon liquid-assisted inverted ILM flap technique group (n = 22, inverted group) or standard ILM removal group (n = 20, peeling group). Outcomes measured were macular hole closure, retinal reattachment, and best-corrected visual acuity at least 6 months after surgery. RESULTS: Macular hole closure was achieved in 20 eyes (90.9%) in the inverted group and in eight eyes (40%) in the peeling group (P < 0.01). Reattachment rates were 100% in the inverted group and 95% in the peeling group (P = 0.476). The mean best-corrected visual acuity improvement from baseline was 27.4 ± 19.9 Early Treatment Diabetic Retinopathy Study letters in the inverted group while the best-corrected visual acuity improvement was 13.6 ± 22.5 Early Treatment Diabetic Retinopathy Study letters in the peeling group (P = 0.044). CONCLUSION: The perfluorocarbon liquid-assisted inverted ILM flap technique was effective in sealing the macular hole, reattaching retina, and improving visual function postoperatively in highly myopic macular hole retinal detachment.

An optimized segmentation and quantification approach in microvascular imaging for OCTA-based neovascular regression monitoring.

BACKGROUND: Quantification of neovascularization changes in terms of neovascular complex (NVC) acquired from the optical coherence tomography angiography (OCTA) imaging is extremely important for diagnosis and treatment monitoring of proliferative diabetic retinopathy (PDR). However, only few vessel extraction methods have so far been reported to quantify neovascular changes in NVC with proliferative diabetic retinopathy PDR based on OCTA images. METHODS: Here we propose an optimized approach to segment blood vessels, which is based on an improved vascular connectivity analysis (VCA) algorithm and combined with morphological characterization and elimination of noise and artifacts. The length and width of vessels are obtained in the quantitative assessment of microvascular network. The feasibility of the proposed method is further studied by a treatment monitoring and statistical analysis process, as we have monitored and statistically analyzed the changes of NVC based on sampled OCTA images of PDR patients (N = 14) after treatment by intravitreal injection of conbercept. RESULTS: The proposed method has demonstrated better performance in accuracy compared with existing algorithms and can thus be used for PRD treatment monitoring. Following the PDR treatment monitoring study, our data has shown that from the 1st day to 7th day of treatment, the averaged (arithmetic mean) length of NVC has been substantially shortened by 36.8% (P < 0.01), indicating significant effects of treatment. Meanwhile, the averaged (arithmetic mean) width of NVC from the 1st day to 7th day of treatment has been increased by 10.2% (P < 0.05), indicating that most of the narrow neovascularization has been reduced. CONCLUSION: The results and analysis have confirmed that the proposed optimization process by the improved VCA method is both effective and feasible to segment and quantify the NVC with lower noise and fewer artifacts. Thus, it can be potentially applied to monitor the fibrovascular regression during the treatment period. Clinical Trial Registration This trial is registered with the Chinese Clinical Trial Registry (Registered 27 December 2017, http://www.chictr.org.cn , registration number ChiCTR-IPR-17014160).

Optimization of Contact Lenses for Corneal Protection During Vitreoretinal Surgery.

OBJECTIVES: To optimize parameters of contact lenses (CLs) and evaluate their ability to protect the cornea during vitreoretinal surgery. METHODS: We compared the protective effects of balanced saline solution, viscoelastic agent, and CLs on rabbit corneas under conditions simulating vitreoretinal surgery. We evaluated CLs of different thicknesses and compared the protective effects of polymethyl methacrylate (PMMA) and gas-permeable fluorosilicone acrylate (XO) lenses on the corneas of rabbits and patients with severe proliferative diabetic retinopathy (PDR). The corneal fluorescein staining score (FSS) was measured to compare the protective effects of CLs. RESULTS: The FSS was significantly lower in the PMMA group than in the balanced saline solution and viscoelastic agent groups. The thickness of the PMMA lenses had no significant effect on the FSS. The FSS was significantly higher in the PMMA group than in the XO group. In patients with PDR, on day 1 after vitreoretinal surgery, the FSS was significantly higher in the PMMA group than in the XO group, although no significant difference was observed on postoperative day 7. CONCLUSION: The XO lens offers better corneal protection during noncontact wide-angle vitreoretinal surgery and protects the corneal epithelium more efficiently during vitrectomy in patients with PDR, irrespective of its thickness.

Minimal internal limiting membrane peeling with ILM flap technique for idiopathic macular holes: a preliminary study.

BACKGROUND: Internal limiting membrane (ILM) peeling increases the idiopathic macular hole (IMH) closure rate but causes the inner retina dimplings. This study is to introduce a method to minimally peel the ILM, and with the ILM flap to ensure the IMH closure. METHODS: Twelve consecutive IMH eyes were treated with the minimal ILM peeling with ILM flap technique. The ILM around the MH is peeled off in an annular shape with a width of approximately 200 to 300 µm. A tongue-shape ILM flap is created in the superior retina and the inferior margin of ILM is not peeled off. The ILM flap is then inverted to cover the MH, followed by fluid-air exchange and air or silicon tamponade. Spectral domain-optical coherence tomography (SD-OCT) and en face OCT for morphological assessment, best corrected visual acuity (BCVA) and multifocal electroretinogram (ERG) for functional evaluation were performed at baseline and at each postoperative follow-up. RESULTS: All the 12 eyes achieved macular hole closure on SD-OCT after surgery (100%). At baseline, the mean preoperative BCVA was 0.83 ± 0.33 and it improved to 0.39 ± 0.28 postoperatively (p <  0.001). En face OCT showed the inner retinal dimplings were localized only in superior ILM-free retinas (7 eyes). The mERG response density in the central (R1), para-central (R2), R1/R2 ring ratios were remarkably improved at the last follow-up (p = 0.001, p = 0.033, p = 0.018, respectively). CONCLUSIONS: The minimal ILM peeling with ILM flap technique can achieve favorable MH closure with less inner retinal dimplings and has promising visual recovery for IMH eyes.

Protective effects of microRNA-22-3p against retinal pigment epithelial inflammatory damage by targeting NLRP3 inflammasome.

NLRP3, as a crucial inflammasome component, plays important roles in age-related macular degeneration. Though some activators of NLRP3 have been studied, microRNAs (miRNAs) which potentially regulate NLRP3 messenger RNA (mRNA) have not been fully explored in retinal pigment epithelial (RPE) cells and retinopathy. In this study, by miRNA microarray profiling and bioinformatic analysis, we identified that four miRNAs, miR-4286, miR-223-3p, miR-365a, miR-22-3p, may target NLRP3 mRNA in RPE inflammatory damage in vivo. Further, real-time polymerase chain reaction verified that only miR-22-3p was significantly decreased, which was associated with NLRP3 upregulation in blue-light-induced retinopathy. Mechanistically, the dual-fluorescent reporter suggested miR-22-3p directly binds NLRP3 mRNA. Moreover, overexpression of miR-22-3p could significantly reduce whereas inhibition miR-22-3p could increase the mRNA and protein expressions of NLRP3, Caspase-1, and mature IL-1ß. Collectively, our results indicate that miR-22-3p plays a suppressive role in RPE damage by targeting NLRP3, which provides new insights into the future intervention to retinopathy.

Real-time photoacoustic sensing for photo-mediated ultrasound therapy.

Photo-mediated ultrasound therapy (PUT) is a novel, noninvasive antimicrovascular approach that can treat neovascularization with high precision. We developed a photoacoustic (PA) sensing (PAS) system for PUT and achieved real-time PAS-guided PUT. Experiments performed on a chicken yolk sac membrane model demonstrated that PAS could monitor the treatment effect in a microvessel during PUT. Vessel shrinkage induced a decrease in the PA signal amplitude, while vessel rupture induced an abrupt increase in the PA signal amplitude. The integrated PUT and PAS system can significantly improve the safety and effectiveness of PUT, and may assist with clinical translation of this novel antimicrovascular technique.

OCT angiography-based monitoring of neovascular regression on fibrovascular membrane after preoperative intravitreal conbercept injection.

PURPOSE: To quantify the preoperative neovascular change pattern on the fibrovascular membrane (FVM) within 7 days after intravitreal injection of conbercept (IVC) using optical coherence tomography angiography (OCTA) in proliferative diabetic retinopathy (PDR). METHODS: Prospective, observational study of PDR patients with visible FVM receiving or not receiving IVC. Neovascular changes were assessed by OCTA pre-IVC and 1, 3, 5, and 7 days post-IVC. Vessel skeleton density (SD) and vessel density (VD) were quantified by an intensity-based optical microangiography algorithm. The interclass correlation coefficient (ICC) was calculated to assess the agreement between measurements. The SD and VD were compared between follow-ups using repeated-measures analysis in the IVC group. RESULTS: The ICC was 0.992 (95% confidence interval [CI]: 0.982-0.996) for SD and 0.926 (95% CI: 0.838-0.912) for VD of neovascularization. The neovascularization on FVM significantly regressed in the IVC group (n = 16) compared with no IVC (n = 8) (p = 0.001 for SD and p < 0.001 for VD). The comparisons between consecutive follow-ups showed a statistically significant reduction in SD and VD at 1 and 3 days post-IVC. However, from day 3 onward, the SD and VD remained unchanged. There was no development or progression of tractional retinal detachment within the 7-day period after IVC. CONCLUSION: OCTA-based quantification of the neovascularization on FVM in PDR is feasible, with high inter-reader agreement. The regression of neovascularization reaches a plateau 3 days after IVC. CLINICAL TRIAL REGISTRATION: This trial is registered with the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , registration number ChiCTR-IPR-17014160).

Thin Rigid Contact Lens Used in Vitreous-Retinal Surgery for Corneal Protection: A Randomized Controlled Trial.

PURPOSE: To design a rigid contact lens (CL) to be used in combination with a wide-angle viewing system and analyze its protection for corneal epithelial during vitreous-retinal surgery. METHODS: A thin and lightweight rigid CL was designed and constructed. The impact of the CL on the visualized fundus range was evaluated using a concrete eye model. Patients with severe proliferative diabetic retinopathy (PDR) were randomized to either the CL group, corneal protective agent (CPA) group, or balanced salt solution (BSS) group. All patients underwent phacoemulsification and a standard 23-gauge three-port vitrectomy. Surgery time and corneal fluorescein staining score (FSS) postoperatively were mainly measured. RESULTS: In the eye model, a larger area of fundus was visualized with the use of our CL under 128 D or 60 D Resight lens. The mean surgery time was 51.36±8.06 min, 50.89±8.26 min, and 55.46±9.14 in CL, CPA, and BSS group, respectively (F=2.325, P=0.105). In eight eyes in the BSS group, corneal epithelial layer was peeled off because the dryness of the cornea could not maintain a clear fundus image. The FSS in BSS group was markedly higher than that of CL and BSS group 1 day (P<0.001), 3 days (P<0.001), and 7 days (P=0.002) postoperatively. There was no statistical significance of the FSS between CL and CPA group at each follow-up endpoint. CONCLUSIONS: The CL that we designed can slightly enlarge the visible fundus range and efficiently protect corneal epithelium during vitrectomy for patients with PDR.

Selective microRNA expression of exosomes from retinal pigment epithelial cells by oxidative stress.

The function of exosomal miRNAs (miRs) in retinal degeneration is largely unclear. We were aimed to investigate the functions of exosomes as well as their miRs derived from retinal pigment epithelial (RPE) cells following exposure to oxidative stress (OS). After the OS by lipopolysaccharide and rotenone on RPE cells, interleukin-1 beta (IL-1ß), Interleukin-6 (IL-6), Tumor Necrosis Factor-alpha (TNF-α) were upregulated, along with the decreased mitochondrial membrane potential and upregulated oxidative damage marker 8-OH-dG in RPE cells. RPE-derived exosomes were then isolated, identified, injected into the subretinal space in mice. After subretinal injection, RPE-exosomes after OS not only induced higher ROS level and apoptotic retinal cells, but also elevated IL-1ß, IL-6 alongside TNF-α expressions among retina/RPE/choroidal complex. Next, miRs inside the exosomes were sequenced by the next generation sequencing (NGS) technology. NGS revealed that certain miRs were abundant in exosomes, while others were selectively kept by RPE cells. Further, downregulated miRs, like miR-125b-5p, miR-125a-5p, alongside miR-128-3p, and upregulated miR, such as miR-7-5p were validated byRT-qPCR. Finally, Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to find the possible target genes of those selective exosomal miRs. Our results proved that the RPE-derived exosomes after OS selectively express certain miRs, providing novel insights into the pathogenesis of age-related macular degeneration (AMD) in future.

Frequency-encoded eye tracking smart contact lens for human-machine interaction.

Eye tracking techniques enable high-efficient, natural, and effortless human-machine interaction by detecting users' eye movements and decoding their attention and intentions. Here, a miniature, imperceptible, and biocompatible smart contact lens is proposed for in situ eye tracking and wireless eye-machine interaction. Employing the frequency encoding strategy, the chip-free and battery-free lens successes in detecting eye movement and closure. Using a time-sequential eye tracking algorithm, the lens has a great angular accuracy of <0.5°, which is even less than the vision range of central fovea. Multiple eye-machine interaction applications, such as eye-drawing, Gluttonous Snake game, web interaction, pan-tilt-zoom camera control, and robot vehicle control, are demonstrated on the eye movement model and in vivo rabbit. Furthermore, comprehensive biocompatibility tests are implemented, demonstrating low cytotoxicity and low eye irritation. Thus, the contact lens is expected to enrich approaches of eye tracking techniques and promote the development of human-machine interaction technology.

Angiogenic and Fibrogenic Dual-effect of Gremlin1 on Proliferative Diabetic Retinopathy.

Ocular angiogenic diseases, such as proliferative diabetic retinopathy (PDR), are often characterized by pathological new vessels and fibrosis formation. Anti-vascular endothelial growth factor (VEGF) therapy, despite of its efficiency to inhibit new vessels, has limitations, including drug resistance and retinal fibrosis. Here, we identified that Gremlin1, a novel angiogenesis and fibrosis inducer, was secreted from Müller glial cells, and its expression increased in the vitreous fluid from patients with PDR. Mechanistically, Gremlin1 triggered angiogenesis by promoting endothelial-mesenchymal transition via the EGFR/RhoA/ROCK pathway. In addition, Gremlin1 activated microglia to present profibrotic and fibrogenic properties. Further, anti-Gremlin1 antibody inhibited ocular angiogenesis and microglia fibrosis in mouse models. Collectively, Gremlin1 could be a potential therapeutic target in the treatment of ocular angiogenic diseases.

Lesion-aware generative adversarial networks for color fundus image to fundus fluorescein angiography translation.

BACKGROUND AND OBJECTIVE: Fundus fluorescein angiography (FFA) is widely used in clinical ophthalmic diagnosis and treatment with the requirement of adverse fluorescent dyes injection. Recently, many deep Convolutional Neural Network(CNN)-based methods have been proposed to estimate FFA from color fundus (CF) images to eliminate the use of adverse fluorescent dyes. However, the robustness of these methods is affected by pathological changes. METHOD: In this work, we present a CNN-based approach, lesion-aware generative adversarial networks (LA-GAN), to enhance the visual effect of lesion characteristics in the generated FFA images. First, we lead the generator notice lesion information by joint learning with lesion region segmentation. A new hierarchical correlation multi-task framework for high-resolution images is designed. Second, to enhance the visual contrast between normal regions and lesion regions, a newly designed region-level adversarial loss is used rather than the image-level adversarial loss. The code is publicly available at: https://github.com/nicetomeetu21/LA-GAN. RESULTS: The effectiveness of LA-Net has been verified in data with branch retinal vein occlusion. The proposed model reported as measures of generation performance a mean structural similarity (SSIM) of 0.536, mean learned perceptual image patch similarity (LPIPS) 0.312, outperforming other FFA generation and general image generation methods. Further, due to the proposed multi-task learning framework, the lesion-region segmentation performance was further reported as the mean Dice increased from 0.714 to 0.797 and the mean accuracy increased from 0.873 to 0.905, outperforming general single-task image segmentation methods. CONCLUSIONS: The results show that the visual effect of lesion characteristics can be improved by employing the region-level adversarial loss and the hierarchical correlation multi-task framework respectively. Based on the results of comparison with the state-of-the-art methods, LA-GAN is not only effective for CF-to-FFA translation, but also effective for lesion-region segmentation. Thus, it may be used for various image translation and lesion segmentation tasks in future research.

Optical Coherence Tomography Angiography for Evaluation of Conjunctival Vessels in Dry Eyes.

Objective: This study aimed to evaluate conjunctival vessels in patients with dry eye disease (DED) using optical coherence tomography angiography (OCTA). Methods: This was a cross-sectional, observational clinical study. Twenty-three eyes of 18 patients with DED and 28 eyes of 23 healthy controls were included for examination in this study. The evaluation included the application of an Ocular Surface Disease Index Questionnaire, Schirmer Basic Secretion Test, and anterior OCTA targeting the temporal conjunctiva. AngioTool software was used to quantify the total vessel length and vessel density in the 3 × 3 mm temporal region of interest. Results: Blood vessel density measurements were compared across the OCTA systems. The total vessel length within the conjunctiva of the DED group (4799.34 ± 834.36) exceeded that of the control eye (3864.89 ± 1455.70) group (P < 0.05). However, the difference in vessel density between the two groups was not statistically significant. Conclusion: Measurement and analysis of conjunctival blood vessels using OCTA exhibited robust repeatability. In dry eyes, the total number of conjunctival blood vessels increased in accordance with disease severity. Hypoxia of conjunctival tissue may be an important cause of dry eye disease.