FROM OUTER RETINAL NEOVACULARIZATION TO EXUDATIVE SUBRETINAL NEOVASCULARIZATION IN MACULAR TELANGIECTASIA TYPE 2.

PURPOSE: To describe the progression from outer retinal neovascularization (ORNV) to exudative subretinal new vessels (SRNVs) in idiopathic macular telangiectasia type 2. METHODS: A total of 135 patients (270 eyes) imaged with optical coherence tomography angiography were included. MAIN OUTCOME MEASURES: Ellipsoid zone loss, outer retinal hyperreflectivity, ORNV, and SRNVs. Outer retinal neovascularization was defined as a flow signal passing through the outer plexiform layer, with or without vertical linear outer retinal hyperreflectivity on the optical coherence tomography B-scan. Subretinal new vessels were defined as an abnormal capillary network with a peripheral anastomotic arcade seen on en face optical coherence tomography angiography and a convex hyperreflectivity at the retinal pigment epithelium. RESULTS: Subretinal new vessels were observed in 38/270 eyes (14%). Subretinal new vessels were at a fibrotic stage in 24/38 eyes and at an exudative stage in 6/38 eyes, and a progression from ORNV to SRNVs was documented in 8/38 eyes. All cases showed an ellipsoid zone loss. In seven eyes (2.5%), SRNVs were also associated with subepithelial neovascularization. No retinochoroidal anastomosis was detected. The visual acuity dropped when SRNVs were present. CONCLUSION: In this case series, SRNVs were found in 14% of eyes. In all cases, they were associated with an ellipsoid zone loss and with outer retinal hyperreflectivity. A progression from ORNV to SRNVs was observed.

Occult retinal neovascularization following intravitreal bevacizumab and laser treatment for retinopathy of prematurity.

BACKGROUND: We present a patient with retinopathy of prematurity (ROP) who developed worsening plus disease after complete regression of stage 3 ROP. The use of fundus fluorescein angiography (FFA) aided the visualization of occult neovascularization that caused the disease progression. CASE PRESENTATION: The patient was at high risk for ROP due to low birth weight of 690 g and gestational age of 25 weeks. After the diagnosis of stage 3 ROP in zone I without plus disease, she was treated initially with bilateral intravitreal bevacizumab (IVB) and followed by laser photocoagulation 5 weeks later. Despite the resolution of ROP stage, the plus disease worsened. Neither systemic risk factors nor skip laser areas were observed. Hence, FFA was performed and subsequently identified occult neovascularization with active leakage. Additional IVB and laser treatment in the capillary dropout area inside vascularized retina were added. The plus disease improved but mild arteriolar tortuosity persisted. CONCLUSIONS: Worsening of plus disease after completion of laser ablation and IVB with complete regression of stage 3 ROP is rare. Systemic risk factors such as continuous oxygen therapy and cardiovascular disease should be ruled out. FFA aided in identifying occult neovascularization and prompted further treatment.

Cytomegalovirus-Associated Non-Necrotizing Retinopathy, Occlusive Retinal Vasculitis, and Neovascularization.

PURPOSE: To report a rare case of cytomegalovirus (CMV)-associated non-necrotizing viral retinopathy, occlusive retinal vasculitis, papillitis, and retinal neovascularization in a young 41-year-old woman. METHODS: Case report. RESULTS: The patient presented with features of papillitis, peripapillary cotton-wool spots, pre-retinal hemorrhages, and occlusive vasculitis. Her visual acuity was 20/100 in the left eye. She developed a worsening of the disease upon initiation of systemic corticosteroids. Her serum immunoglobulins (Ig) (both IgG and IgM) were highly positive for CMV. Anterior chamber paracentesis was positive for CMV DNA using real-time polymerase chain reaction. After stopping systemic corticosteroids, she was initiated on oral valganciclovir, with rapid resolution of the vasculitis and cotton-wool spots. After three months, the patient developed retinal neovascularization and underwent pan-retinal photocoagulation. However, her uveitis was inactive, and her visual acuity improved to 20/25. CONCLUSIONS: Non-necrotizing viral retinopathy has been associated with either varicella zoster virus (VZV) or herpes simplex virus (HSV). Our case highlights that CMV can also lead to non-necrotizing retinopathy and must be suspected in patients who may be negative for VZV and HSV. Appropriate anti-viral treatment can prevent severe vision loss in these patients.

The potential key role of choroidal non-perfusion and rod degeneration in the pathogenesis of macular neovascularization type 3.

Macular neovascularization type 3 (MNV3) is a multifactorial disease with distinct epidemiological, clinical, pathomorphological and topographical characteristics. This review of the literature discusses the latest experimental and clinical outcomes that could explain the pathogenesis of retinal neovascularization. Although patients with MNV3 are usually older than those with MNV1 or 2, their lesions do not coexist with, precede, or follow other types in the same eye. The regional distribution of MNV3 lesions is characterized as confined to the parafoveal macula without any involvement of the rod-free foveal area. Focal outer retinal atrophy and choroidal non-perfusion are the main structural features that occur prior to the development of retinal neovascularization. Also, histological and experimental studies of MNV3 and other non-neovascular age-related macular degeneration diseases complicated with MNV3-like lesions strongly suggest rod degeneration contributes to the pathogenesis. Therefore, the retinal neovascularization in MNV3 has a different pathogenesis from the choroidal neovascularization in MNV1 and 2 and emerging evidence indicates that choroidal non-prefusion and rod degeneration play a key role in the pathogenesis of MNV3. Accordingly, we suggest a sequence of pathological events that start with choroidal non-perfusion due to advanced age followed by hypoxia of the outer retina at the parafoveal area. This induces a remarkable degeneration of rods that triggers the growth of retinal neovascularization due to the imbalance of the angiogenic factors in the outer retina.

SOCS3 regulates pathological retinal angiogenesis through modulating SPP1 expression in microglia and macrophages.

Pathological ocular angiogenesis has long been associated with myeloid cell activation. However, the precise cellular and molecular mechanisms governing the intricate crosstalk between the immune system and vascular changes during ocular neovascularization formation remain elusive. In this study, we demonstrated that the absence of the suppressor of cytokine signaling 3 (SOCS3) in myeloid cells led to a substantial accumulation of microglia and macrophage subsets during the neovascularization process. Our single-cell RNA sequencing data analysis revealed a remarkable increase in the expression of the secreted phosphoprotein 1 (Spp1) gene within these microglia and macrophages, identifying subsets of Spp1-expressing microglia and macrophages during neovascularization formation in angiogenesis mouse models. Notably, the number of Spp1-expressing microglia and macrophages exhibited further elevation during neovascularization in mice lacking myeloid SOCS3. Moreover, our investigation unveiled the Spp1 gene as a direct transcriptional target gene of signal transducer and activator of transcription 3. Importantly, pharmaceutical activation of SOCS3 or blocking of SPP1 resulted in a significant reduction in pathological neovascularization. In conclusion, our study highlights the pivotal role of the SOCS3/STAT3/SPP1 axis in the regulation of pathological retinal angiogenesis.

Factors associated with the development of exudation in treatment-naive eyes with nonexudative macular neovascularization.

PURPOSE: To identify the predictive factors for development of exudation in patients with treatment-naïve nonexudative macular neovascularization (MNV). METHODS: We retrospectively analyzed 61 treatment-naïve patients with nonexudative MNV who had not received treatment for nonexudative MNV before the exudation developed. Baseline characteristics and changes in MNV were evaluated using multivariate modeling to determine the potential risk factors for exudative conversion. RESULTS: Exudation development was identified in 31.1% (19/61 eyes) of the study eyes during the 46.2 ± 8.2-month mean follow-up period. The mean period of development of exudation from the baseline was 21.5 ± 6.7 months. Multivariate Cox regression analysis identified that older age (hazard ratio [HR] of 1.380, 95% confidence interval [CI] 1.129-1.688, P = 0.008), larger MNV area at baseline (HR of 1.715, CI 1.288-2.308; P = 0.006), increase of MNV area by doubling (HR of 4.992, CI 1.932-9.246; P = 0.002), and retinal pigment epithelium (RPE) elevation more than 100 µm (HR of 1.017, CI 1.006-1.233; P = 0.015) were associated with increased risk of the development of exudation. CONCLUSION: Older age, larger MNV area, increasing MNV area, and higher RPE elevation were associated with an increased risk of exudative conversion in patients with treatment-naïve nonexudative MNV. Identifying these risk factors may be helpful in establishing treatment strategies and monitoring patients.

Characteristics, Etiology, and Clinical Outcome of Retinal Vasculitis in Tertiary Hospital in Thailand.

OBJECTIVE: To analyze characteristics, etiology, and outcome of retinal vasculitis in Central Thailand. METHODS: A retrospective cohort study. RESULTS: Retinal vasculitis was found in 10% of uveitis, 74 from 741 uveitis, noninfectious (64.9%) and infectious group (35.1%). The most common cause was Behcet's disease (48.6%). Behcet's disease was the most common cause of all types of vascular leakage on angiography, including capillary (80.4%), venous (56.3%), and arterial leakage (56%). Final visual acuity was 0.86 ± 0.97 logMAR. Cataract was the most frequent complication (42.5%). Acute clinical course (p = .025) and retinal neovascularization (p = .031) were associated with infectious group. Forty-three percent of vasculitis complicated by ischemia required photocoagulation (33%) and anti-VEGF injection (17%). Furthermore, 17% of vasculitis underwent vitrectomy. CONCLUSION: One-half of the retinal vasculitis in Central Thailand were Behcet's disease. Acute onset and retinal neovascularization may suggest infectious etiology. Retinal ischemia should be cautious and undergo early interventions to prevent sight-threatening complications.

Reperfusion of retinal nonperfusion by neovascular-vascular anastomosis in proliferative diabetic retinopathy.

BACKGROUND: Retinal nonperfusion is a significant cause of vision loss in patients with proliferative diabetic retinopathy (PDR). Therefore, reperfusion of a nonperfusion has been a matter of strong interest, but few previous studies have demonstrated the potential benefits of reperfusion. CASE REPORTS: Here, we report longitudinal optical coherence tomography angiographic analysis of two cases of PDR, in which the retinal neovascularization (RNV) that developed in response to retinal ischemia formed anastomoses with pre-existing physiological retinal vessels, resulting in both superficial and deep capillary reperfusion within the nonperfusion. We named this interesting finding "neovascular-vascular anastomosis." Retinal reperfusion due to neovascular-vascular anastomosis differed from recanalization, defined as reperfusion of once-occluded blood vessels, and has not been reported previously. CONCLUSION: Our observation highlights the potential of RNV to rescue retinal ischemia by the formation of neovascular-vascular anastomoses.

Limited Hyperoxia-Induced Proliferative Retinopathy (LHIPR) as a Model of Retinal Fibrosis, Angiogenesis, and Inflammation.

The progression to fibrosis and traction in retinopathy of prematurity (ROP) and other ischemic retinopathies remains an important clinical and surgical challenge, necessitating a comprehensive understanding of its pathogenesis. Fibrosis is an unbalanced deposition of extracellular matrix components responsible for scar tissue formation with consequent tissue and organ impairment. Together with retinal traction, it is among the main causes of retinal detachment and vision loss. We capitalize on the Limited Hyperoxia Induced Retinopathy (LHIPR) model, as it reflects the more advanced pathological phenotypes seen in ROP and other ischemic retinopathies. To model LHIPR, we exposed wild-type C57Bl/6J mouse pups to 65% oxygen from P0 to P7. Then, the pups were returned to room air to recover until later endpoints. We performed histological and molecular analysis to evaluate fibrosis progression, angiogenesis, and inflammation at several time points, from 1.5 months to 9 months. In addition, we performed in vivo retinal imaging by optical coherence tomography (OCT) or OCT Angiography (OCTA) to follow the fibrovascular progression in vivo. Although the retinal morphology was relatively preserved, we found a progressive increase in preretinal fibrogenesis over time, up to 9 months of age. We also detected blood vessels in the preretinal space as well as an active inflammatory process, altogether mimicking advanced preretinal fibrovascular disease in humans.

Topographic distribution of retinal neovascularization in proliferative diabetic retinopathy using ultra-wide field angiography.

Purpose: To analyze the topographic distribution of neovascularization (NV) and capillary nonperfusion (CNP) using ultra-wide field fluorescein angiography (UWFFA) in patients with proliferative diabetic retinopathy (PDR). Methods: This was a prospective, single-center, observational study in which all patients who presented between March 2019 and December 2020 and satisfied the inclusion criteria were recruited. In our study, patients with treatment-naïve PDR without any fibrovascular proliferation underwent UWFFA. The images were analyzed qualitatively for the topographic distribution of NV and the CNP area was quantified. The number of lesions picked by UWFFA was compared with 7 standard field (7SF) image using overlay of 7SF. The main outcome measure was characteristics of neovascularization, such as the number, location, and area of CNP, measured using UWFFA, which was considered with 95% confidence intervals (CI). Results: Two hundred and fifty-three eyes of 187 patients with a mean age of 56.03 ± 8 years were included. Mean neovascularization elsewhere (NVE) was 2.91 ± 3.43. Maximum NVEs were seen in the superotemporal (ST; 0.9 ± 1.13) quadrant, followed by the inferotemporal (IT; 0.7 ± 1.08), inferonasal (IN; 0.66 ± 1.02) and superonasal (SN; 0.66 ± 1.01) quadrants. Maximum CNP area was seen in the SN (13.75 ± 8.83 disc diameter square [DD2]) quadrant, followed by the IN (13.48 ± 8.59 DD2), IT (11.34 ± 8.37 DD2), and ST (11.3 ± 8.34 DD2) quadrants. Mean CNP area was maximum in patients with only neovascularization of disc (NVD; 64.99 ± 41.47 DD2), followed by both NVD and NVE (61.37 ± 35.61 DD2), and was minimum in patients with only NVE (36.44 ± 22.03 DD2). Eighty-one (32%) eyes out of 253 had NVE and 189 (75%) out of 253 had CNP area outside 7SF (overlay) of Early Treatment Diabetic Retinopathy Study (ETDRS). Conclusion: Diabetic NV lesions and CNP areas are distributed asymmetrically throughout the retina and are not restricted to the posterior pole. Compared to conventional 7SF imaging, UWFFA reveals significantly more retinal vascular pathology in patients with PDR.

Oxygen-Induced Retinopathy in the Rat: An Animal Model to Study the Proliferative Retinal Vascular Pathology.

Diabetic retinopathy (DR) is one of the leading causes of vision loss worldwide. There are numerous animal models available for developing new ocular therapeutics and drug screening and to investigate the pathological processes involved in DR. Among those animal models, the oxygen-induced retinopathy (OIR) model, though originally developed as a model for retinopathy of prematurity, has also been used to investigate angiogenesis in proliferative DR with the phenomenon of ischemic avascular zones and pre-retinal neovascularization it demonstrated. Briefly, neonatal rodents are exposed to hyperoxia to induce vaso-obliteration. Upon removal from hyperoxia, hypoxia develops in the retina that eventually results in neovascularization. The OIR model is mostly used in small rodents such as mice and rats. Here, we describe a detailed experimental protocol of rat OIR model and the subsequent assessment of abnormal vasculature. By illustrating the vasculoprotective and anti-angiogenic activities of the treatment, OIR model might advance to a new platform for investigating novel ocular therapeutic strategies for DR.

Utility of En Face OCT for the Detection of Clinically Unsuspected Retinal Neovascularization in Patients with Diabetic Retinopathy.

PURPOSE: To assess the value of en face OCT for detecting clinically unsuspected retinal neovascularization (RNV) in patients with nonproliferative diabetic retinopathy (NPDR). DESIGN: A retrospective, cross-sectional study. PARTICIPANTS: Treatment-naïve patients clinically graded as NPDR in an ongoing prospective observational OCT angiography (OCTA) study at a tertiary care center. METHODS: Each patient underwent imaging of 1 eye with a spectral-domain OCTA, generating a 17 × 17-mm widefield image by montaging four 9 × 9-mm scans. Two independent graders examined a combination of en face OCT, en face OCTA with a custom vitreoretinal interface slab, and cross-sectional OCTA to determine the presence of RNV. We measured the area of RNV flow within RNV lesions on en face OCTA. MAIN OUTCOME MEASURES: Detection rate of clinically occult RNV with OCT and OCTA. RESULTS: Of 63 enrolled eyes, 27 (43%) were clinically graded as severe NPDR, 16 (25%) as moderate NPDR, and 20 (32%) as mild NPDR. Using the combination of en face OCT, en face OCTA, and cross-sectional OCTA, the graders detected 42 RNV lesions in 12 (19%) eyes, of which 8 (67%) were graded as severe NPDR, 2 (17%) as moderate NPDR, and 2 (17%) as mild NPDR. The sensitivity of en face OCT alone for detecting eyes with RNV was similar to that of en face OCTA alone (100% vs. 92%; P = 0.32), whereas the specificity of en face OCT alone was significantly lower than that of en face OCTA alone (32% vs. 73%; P < 0.001). For detecting individual RNV lesions, the en face OCT was 100% sensitive, compared with 67% sensitivity for the en face OCTA (P < 0.001). The area of RNV lesions that manual grading with en face OCTA alone missed was significantly smaller than that of manually detectable RNV (Mean [standard deviation] RNV flow area, 0.015 [0.020] mm2 vs. 0.16 [0.36] mm2; P < 0.001). CONCLUSION: The combination of en face OCT and OCTA can detect clinically occult RNV with high sensitivity. For screening these small lesions, en face OCT may be a useful imaging modality. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

CENTRAL RETINAL VEIN OCCLUSION IN 12-YEAR-OLD GIRL WITH METHYLENETETRAHYDROFOLATE REDUCTASE MUTATION: A CASE REPORT AND REVIEW OF THE LITERATURE.

PURPOSE: This case report describes a central retinal vein occlusion in a healthy 12-year-old girl who developed retinal neovascularization at 24 years of age. To the knowledge of the authors, this is the longest time between a reported pediatric central retinal vein occlusion event and neovascularization. METHODS: The patient underwent a full history, physical examination, and laboratory workup to determine potential risk factors contributing to the vascular event. Fundus photographs, optical coherence tomography, and fluorescein angiography were performed throughout the patient's treatment course. RESULTS: Family history was noncontributory, but laboratory testing revealed a mildly elevated homocysteine level and homozygous C677T mutation in methylenetetrahydrofolate reductase. As a result, she was started on folate supplementation. The patient has had no further ocular or systemic thrombotic events to date. CONCLUSION: Pediatric patients presenting with central retinal vein occlusion should undergo a systemic workup and require long-term follow-up to avoid complications, such as intraocular hemorrhage, tractional retinal detachments, and neovascular glaucoma.

RETINAL NEOVASCULARIZATION IN ACQUIRED PERIPHERAL RETINOSCHISIS THROUGH INNER RETINAL ISCHEMIA: OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHIC FINDINGS.

PURPOSE: To present two cases of concomitant retinal neovascularization (RNV) in acquired peripheral retinoschisis and analyze its characteristics on optical coherence tomography angiography and based on a literature review. METHODS: This was an observational, retrospective case study. RESULTS: Case 1 presented with bullous retinoschisis and RNV near the schisis cavity. Optical coherence tomography angiography revealed no angioflow into the retinal arterioles of the cavity. An arterial filling delay to the retinoschisis with extensive leakage from the RNV was noted on fluorescein angiography. Case 2 involved the superficial retinoschisis and telangiectatic vessels inside the schisis cavity. Optical coherence tomography angiography revealed damage to the superficial capillary plexus of the cavity, absence of angioflow to the inner schisis layer, and increased angioflow to the RNV. Fluorescein angiography showed focal leakage from the RNV and diffuse leakage from telangiectasia. No vision-threatening complications were identified in either patient up to the last follow-up, subsequent to laser photocoagulation. CONCLUSION: Acquired peripheral retinoschisis is associated with RNV. Inner retinal ischemia caused by hemodynamic resistance or a damaged superficial capillary plexus can interrupt angioflow to the inner schisis retinal layer on optical coherence tomography angiographic findings and develop RNV inside or outside the retinoschisis.

Long non-coding RNAs in retinal neovascularization: current research and future directions.

PURPOSE: Retinal neovascularization (RNV) is an intractable pathological hallmark of numerous ocular blinding diseases, including diabetic retinopathy, retinal vein occlusion, and retinopathy of prematurity. However, current therapeutic methods have potential side effects and limited efficacy. Thus, further studies on the pathogenesis of RNV-related disorders and novel therapeutic targets are critically required. Long non-coding RNAs (lncRNAs) have various functions and participate in almost all biological processes in living cells, such as translation, transcription, signal transduction, and cell cycle control. In addition, recent research has demonstrated critical modulatory roles of various lncRNAs in RNV. In this review, we summarize current knowledge about the expression and regulatory functions of lncRNAs related to the progression of pathological RNV. METHODS: We searched databases such as PubMed and Web of Science to gather and review information from the published literature. CONCLUSIONS: In general, lncRNA MEG3 attenuates RNV, thus protecting the retina from excessive and dysregulated angiogenesis under high glucose stress. In contrast, lncRNAs MALAT1, MIAT, ANRIL, HOTAIR, HOTTIP, and SNHG16, have been identified as causative molecules in the pathological progression of RNV. Comprehensive and in-depth studies of the roles of lncRNAs in RNV indicate that targeting lncRNAs may be an alternative therapeutic approach in the near future, enabling new options for attenuating RNV progression and treating RNV-related retinal diseases.

Deletion of Tgfß signal in activated microglia prolongs hypoxia-induced retinal neovascularization enhancing Igf1 expression and retinal leukostasis.

Retinal neovascularization (NV) is the major cause of severe visual impairment in patients with ischemic eye diseases. While it is known that retinal microglia contribute to both physiological and pathological angiogenesis, the molecular mechanisms by which these glia regulate pathological NV have not been fully elucidated. In this study, we utilized a retinal microglia-specific Transforming Growth Factor-ß (Tgfß) receptor knock out mouse model and human iPSC-derived microglia to examine the role of Tgfß signaling in activated microglia during retinal NV. Using a tamoxifen-inducible, microglia-specific Tgfß receptor type 2 (Tgfßr2) knockout mouse [Tgfßr2 KO (ΔMG)] we show that Tgfß signaling in microglia actively represses leukostasis in retinal vessels. Furthermore, we show that Tgfß signaling represses expression of the pro-angiogenic factor, Insulin-like growth factor 1 (Igf1), independent of Vegf regulation. Using the mouse model of oxygen-induced retinopathy (OIR) we show that Tgfß signaling in activated microglia plays a role in hypoxia-induced NV where a loss in Tgfß signaling microglia exacerbates and prolongs retinal NV in OIR. Using human iPSC-derived microglia cells in an in vitro assay, we validate the role of Transforming Growth Factor-ß1 (Tgfß1) in regulating Igf1 expression in hypoxic conditions. Finally, we show that Tgfß signaling in microglia is essential for microglial homeostasis and that the disruption of Tgfß signaling in microglia exacerbates retinal NV in OIR by promoting leukostasis and Igf1 expression.

OCT-angiography for diagnosis and response to treatment of subretinal neovascularization secondary to idiopathic macular telangiectasia type 2.

Idiopathic macular telangiectasia type 2 (MacTel 2) is a slow and progressive bilateral condition that affects middle-aged and elderly individuals. Vision loss is generally mild and occurs over the course of many years. The development of sub-retinal neovascularisation (SRNV) can occur late in the disease process, and lead to more dramatic vision loss. A report is presented of 2 cases of MacTel 2 in which optical coherence tomography angiography (OCTA) was essential for the diagnosis of secondary SRNV. The commercially available OCTA Cirrus AngioPlex 5000 platform (Zeiss, Jena, Germany) was used. Subretinal neovascularization was detectable in both cases in OCTA at the level of the deep capillary plexus and the avascular layer. OCTA also allowed us to monitor disease progression and monitor response to anti-VEGF therapy.

Henle Fiber Layer Hemorrhage in Macular Telangiectasia Type 2: Is Right Eye Dominance Coincidence or Consequence?

PURPOSE: To summarize all reported cases of Henle fiber layer (HFL) hemorrhage in the absence of subretinal neovascularization (SRNV) in patients with macular telangiectasia type 2 (MacTel2) and to propose a mechanism for the right-sided predominance of this unique presentation. DESIGN: Perspective. METHODS: Collection, review, and analysis of all cases in the literature and in the authors' databases of HFL hemorrhage in MacTel2, including analysis of baseline and follow-up multimodal retinal imaging findings of selected cases. Elucidation of the complex interplay of systemic venous pressure with the deep retinal capillary plexus and hypothesis regarding the right-sided predilection of HFL hemorrhage complicating MacTel2. RESULTS: Ten patients presented with a unilateral, characteristic radial macular hemorrhage within the HFL that affected only the right eye in all cases. Absence of SRNV was confirmed by fluorescein angiography and/or optical coherence tomography angiography. The hemorrhage resolved spontaneously in at least 7 of the 10 eyes. The HFL hemorrhage may plausibly be explained by dysfunction of the deep capillary plexus in MacTel2 combined with an acute rise in central venous pressure, for which the right side may be at increased risk. CONCLUSIONS: HFL hemorrhage can complicate MacTel2 in the absence of SRNV, and the radial pattern of blood affecting only the right eye is remarkable. The right eye predominance may be multifactorial in etiology. Related factors may include the right-sided predilection of MacTel2 and/or increased right-sided dural sinus drainage related to normal anatomical variation.

Limited hyperoxia-induced proliferative retinopathy: A model of persistent retinal vascular dysfunction, preretinal fibrosis and hyaloidal vascular reprogramming for retinal rescue.

BACKGROUND: Retinopathy of prematurity (ROP) remains the leading cause for blindness in children. Limited hyperoxia induced proliferative retinopathy (L-HIPR) was recently introduced as a potential animal model for ROP and persistent fetal vasculature; however, the detailed pathological changes remain unclear. METHODS: To model L-HIPR, we placed C57BL/6J mice in 65% oxygen from birth to post-natal day 7 (P7). We examined eyes at intervals between P12 and P30. Retinal morphometry, thickness, and preretinal fibrosis were quantified at different time points on histological sections stained with hematoxylin and eosin (H&E) and Masson Trichrome, respectively. Vascular development, angiogenesis, inflammation, and pericyte coverage were analyzed using immunohistochemistry staining in retinal flat mounts and cross sections. RESULTS: In L-HIPR, the hyaloidal vessels persisted until the latest time point in this study, P30 and began to invaginate the peripheral then central retina starting at P12. Central retinal distortion was noted beginning at P17, while the peripheral retina demonstrated a trend of thinning from P12 to P30. We found that L-HIPR was associated with delayed and abnormal retinal vascular development with subsequent retinal inflammation, pericyte loss and preretinal fibrosis. CONCLUSION: Our study presents a detailed analysis of the L-HIPR animal model demonstrating vitreoretinal pathologic changes, preretinal fibrosis and persistent hyaloidal vessels into adulthood. Based on our findings, we suggest that the persistence and peculiar stepwise migration of the hyaloidal vessels into the retina may provide a potential rescue mechanism for inner retinal development that deserves further study.

VEGF-targeting drugs for the treatment of retinal neovascularization in diabetic retinopathy.

Diabetic retinopathy (DR) is the most common microangiopathic complication of diabetes mellitus, representing a major cause of visual impairment in developed countries. Proliferative DR (PDR) represents the last stage of this extremely complex retinal disease, characterized by the development of neovascularization induced by the abnormal production and release of vascular endothelial growth factor (VEGF). The term VEGF includes different isoforms; VEGF-A represents one of the most important pathogenic factors of DR. Anti-VEGF intravitreal therapies radically changed the outcome of DR, due to combined anti-angiogenic and anti-edematous activities. Nowadays, several anti-VEGF molecules exist, characterized by different pharmacological features and duration. With respect to PDR, although anti-VEGF treatments represented a fundamental step forward in the management of this dramatic complication, a big debate is present in the literature regarding the role of anti-VEGF as substitute of panretinal photocoagulation or if these two approaches may be used in combination. In the present review, we provided an update on VEGF isoforms and their role in DR pathogenesis, on current anti-VEGF molecules and emerging new drugs, and on the current management strategies of PDR. There is an overall agreement regarding the relative advantage provided by anti-VEGF, especially looking at the management of PDR patients requiring vitrectomy, with respect to laser. Based on the current data, laser approaches might be avoided when a perfectly planned anti-VEGF therapeutic strategy can be adopted. Conversely, laser treatment may have a role for those patients unable to guarantee enough compliance to anti-VEGF injections.Key messagesVEGF increased production, stimulated by retinal hypoperfusion and ischaemia, is a major pathogenic factor of neovascular complication onset in diabetic retinopathy and of DR stages progression.Nowadays, several anti-VEGF molecules are available in clinical practice and other molecules are currently under investigation. Each anti-VEGF molecule is characterized by different targets and may interact with multiple biochemical pathways within the eye.All the data agreed in considering anti-VEGF molecules as a first line choice for the management of diabetic retinopathy. Laser treatments may have a role in selected advanced cases and for those patients unable to guarantee enough compliance to intravitreal treatments schemes.