Defective endothelial cell migration in the absence of Cdc42 leads to capillary-venous malformations.

Formation and homeostasis of the vascular system requires several coordinated cellular functions, but their precise interplay during development and their relative importance for vascular pathologies remain poorly understood. Here, we investigated the endothelial functions regulated by Cdc42 and their in vivo relevance during angiogenic sprouting and vascular morphogenesis in the postnatal mouse retina. We found that Cdc42 is required for endothelial tip cell selection, directed cell migration and filopodia formation, but dispensable for cell proliferation or apoptosis. Although the loss of Cdc42 seems generally compatible with apical-basal polarization and lumen formation in retinal blood vessels, it leads to defective endothelial axial polarization and to the formation of severe vascular malformations in capillaries and veins. Tracking of Cdc42-depleted endothelial cells in mosaic retinas suggests that these capillary-venous malformations arise as a consequence of defective cell migration, when endothelial cells that proliferate at normal rates are unable to re-distribute within the vascular network.

INTERVORTEX VENOUS ANASTOMOSIS IN Pachychoroid-RELATED DISORDERS.

PURPOSE: To evaluate the choroidal vascular patterns of patients with pachychoroid-related diseases in eyes images with wide-field indocyanine green angiography. METHODS: Retrospective study of wide-field indocyanine green angiographic images of patients with pachychoroid, peripapillary pachychoroid syndrome, central serous chorioretinopathy, and pachychoroid-associated neovascularization that were evaluated for anastomoses between vortex vein systems, which are ordinarily separated by a watershed zone. RESULTS: There were 21 subjects with a mean age of 57.4 years and 15 were male. Among the 42 eyes evaluated, central serous chorioretinopathy was found in 24 eyes (57.1%), peripapillary pachychoroid syndrome in 5 (11.9%), pachychoroid associated neovascularization in 7 (16.7%), and pachychoroid in 6 (14.3%). Every eye showed anastomosis between the superonasal, superotemporal, and inferotemporal vortex vein systems. The inferonasal vortex vein system was less likely to demonstrate anastomosis except for peripapillary pachychoroid syndrome, which showed anastomosis in all eyes. The anastomotic connections were prominent in the central macula in the central serous chorioretinopathy and pachychoroid-associated neovascularization cases, and around the nerve in the peripapillary pachychoroid syndrome cases. Although the large choroidal veins were particularly prominent in the neovascular cases, the number was fewer in the macular region than in other pachychoroid-related diseases in this series. Compared with a control group of nine eyes, the inferotemporal-superotemporal-superonasal anastomotic connections were more common in the case group (P < 0.001) and inferonasal quadrant (P = 0.023 right eye; P = 0.01, left eye). CONCLUSION: Intervortex venous anastomosis is common in pachychoroid, central serous chorioretinopathy, peripapillary pachychoroid syndrome, and pachychoroid-associated neovascularization. This finding has important implications concerning pathogenesis and classification of disease.

Arteriovenous crossing in retinal vessels of mice, rats, and pigs.

Purpose: Retinal vein occlusions (RVOs) are a common disease, but there are no animal models for spontaneous RVO formation. The critical sites of predilection, especially for branch RVO (BRVO), are the arteriovenous crossing sites in the inner retina. To gain more insight into possible animal models, the anatomic structure of retinal arteriovenous crossings was investigated in mice, rats, and pigs and compared to the human situation. Methods: Retinal flat mounts and paraffin sections of eyes from mice, rats, pigs, and humans were stained with GS lectin, Masson's trichrome, or immunohistochemistry for ACTA2 and GFAP. Serial sections of arteriovenous crossing sites were investigated. Results: Mice usually do not show retinal arteriovenous crossings. Rats have a mean of 2.8±1.4 crossings per eye at a mean distance from the optic nerve head of 2.79±0.53 mm, though the diameters of the crossing vessels are small. The situation in pigs is similar to that in humans, with many arteriovenous crossings of vessels and with similar diameters as found in humans. A mean of 28.4±3.5 crossings per retina was found, and 23% of these were arterial overcrossings. Serial paraffin sections showed that the tunica media of the artery touched that of the vein, but they did not fuse. Conclusions: While the retinal arteriovenous crossings of mice and rats are absent or comprised of rather thin vessels, those in the porcine retina are similar to adult humans. Therefore, the porcine retinal vascular bed may serve as a model to assess early steps in the formation of RVOs.

Binarization of enhanced depth imaging optical coherence tomographic images of an eye with Wyburn-Mason syndrome: a case report.

BACKGROUND: To report a thicker choroid and larger choroidal luminal area in an eye with Wyburn-Mason syndrome. To the best of our knowledge, this is the first report demonstrating an increase in the choroidal thickness and the luminal area in a case of Wyburn-Mason syndrome. In addition, we report the changing appearance of retinal arteriovenous malformations over a 16-year period. CASE PRESENTATION: A 27-year-old woman, who was diagnosed with Wyburn-Mason syndrome at age 11 years, visited our clinic. Her best-corrected visual acuity was 20/12.5 in the right eye and light perception in the left eye. Severely dilated, tortuous vascular loops were distributed from the optic disc over all four quadrants of the left fundus. The vascular loops in some areas were more dilated and tortuous than 16 years earlier. Optical coherence tomography (OCT) showed retinal edema with cystic changes and enlarged choroidal vessel lumens in the left eye. The subfoveal choroidal thickness was manually measured by the caliper function in the enhanced depth imaging OCT (EDI-OCT) images. Binarization of the EDI-OCT images was performed with publicly accessible ImageJ software. The examined area of the subfoveal choroid was 1,500 µm wide, and the dark areas representing the luminal areas were traced by the Niblack method. After determining the distance of each pixel, the luminal area was automatically calculated. The subfoveal choroidal thickness was 250 µm in the right eye and 462 µm in the left eye. The luminal area of the 1,500-µm-wide subfoveal choroid was computed to be 307,165.6 µm(2) in the right eye and 545,780.7 µm(2) in the left eye. CONCLUSIONS: The EDI-OCT images showed a thicker choroid, and binarization of the EDI-OCT images showed that the luminal areas were significantly larger in the affected eye, suggesting a dilatation of the choroidal vessels. The results demonstrated that conversion of EDI-OCT images to binary images was a useful method to quantify the choroidal structure.

Plus disease diagnosis in retinopathy of prematurity: vascular tortuosity as a function of distance from optic disk.

PURPOSE: To examine vascular tortuosity as a function of distance from the optic disk in infants with retinopathy of prematurity. METHODS: Thirty-four wide-angle retinal images from infants with retinopathy of prematurity were reviewed by 22 experts. A reference standard for each image was defined as the diagnosis (plus vs. not plus) given by the majority of experts. Tortuosity, defined as vessel length divided by straight line distance between vessel end points, was calculated as a function of distance from the disk margin for arteries and veins using computer-based methods developed by the authors. RESULTS: Mean cumulative tortuosity increased with distance from the disk margin, both in 13 images with plus disease (P = 0.007 for arterial tortuosity [n = 62 arteries], P < 0.001 for venous tortuosity [n = 58 veins] based on slope of best fit line by regression), and in 21 images without plus disease (P < 0.001 for arterial tortuosity [n = 94 arteries], P <0 .001 for venous tortuosity [n = 85 veins]). Images with plus disease had significantly higher vascular tortuosity than images without plus disease (P < 0.05), up to 7.0 disk diameters from the optic disk margin. CONCLUSION: Vascular tortuosity was higher peripherally than centrally, both in images with and without plus disease, suggesting that peripheral retinal features may be relevant for retinopathy of prematurity diagnosis.

Mature vessel occlusion after anti-VEGF treatment in a retinal arteriovenous malformation.

BACKGROUND: To report engorged vessel occlusion after repeated intravitreal injections of bevacizumab to treat the macular oedema in a case of arteriovenous malformation. CASE PRESENTATION: A 37-year-old woman presented with a sudden, painless loss of vision in her left eye. Her visual acuity was 20/200 in the left eye, and 20/20 in the right eye. Ophthalmoscopic examination revealed an abnormal tangle of vessels and enlarged draining veins. A fluorescence angiogram revealed fluorescence leakage at a turn near the fovea. Horizontally oriented optical coherence tomography revealed an increased macular thickness and an accumulation of intraretinal fluid, indicating macular oedema. After three intravitreal injections of 1.25 mg bevacizumab, her vision improved to 20/20. Ophthalmoscopic examination revealed a decreased calibre of the previously engorged draining veins and ghost vessels. Repeated horizontally oriented optical coherence tomography revealed a decreased macular thickness and the absence of an intraretinal cyst. At the 2-year follow-up visit, the vision of the patient was stable. CONCLUSION: This finding implies that certain middle-size vessels can become occluded during anti-vascular endothelium growth factor (anti-VEGF) therapy, which could induce fatal complications if it occurred in the heart or brain. Clinicians should be cautious of the potential thrombotic effects on systemic blood vessels when administering anti-VEGF treatment.

Retinal angiomatous proliferation in age­related macular degeneration. 2001.

BACKGROUND: It is known that choroidal neovascularization (CNV) in age-related macular degeneration (ARMD) may erode through the retinal pigment epithelium, infiltrate the neurosensory retina, and communicate with the retinal circulation in what has been referred to as a retinal­choroidal anastomosis (RCA). This is extremely common in the end stage of disciform disease. In recent years, the reverse also seems to be possible, as angiomatous proliferation originates from the retina and extends posteriorly into the subretinal space, eventually communicating in some cases with choroidal new vessels. This form of neovascular ARMD, termed retinal angiomatous proliferation (RAP) in this article, can be confused with CNV. PURPOSE: The purpose of this article is 1) to review the clinical and angiographic characteristics of a series of patients with RAP and 2) to propose a theoretical sequence of events that accounts for the neovascularized process. METHODS: In this retrospective clinical and angiographic analysis, 143 eyes with RAP (108 patients) were reviewed and classified based on their vasogenic nature and course. Clinical biomicroscopic examination, fluorescein angiography, and indocyanine green angiography were used to evaluate patients. RESULTS: The results of this series suggest that angiomatous proliferation within the retina is the first manifestation of the vasogenic process in this form of neovascular ARMD. Dilated retinal vessels and pre-, intra-, and subretinal hemorrhages and exudate evolve, surrounding the angiomatous proliferation as the process extends into the deep retina and subretinal space. One or more dilated compensatory retinal vessels perfuse and drain the neovascularization, sometimes forming a retinal­retinal anastomosis. Fluorescein angiography in these patients usually revealed indistinct staining simulating occult CNV. Indocyanine green angiography was useful to make an accurate diagnosis in most cases. It revealed a focal area of intense hyperfluorescence corresponding to the neovascularization ("hot spot") and other characteristic findings. Based on understanding of the nature and progression of the neovascularized process, patients with RAP were classified into three vasogenic stages. Stage I involved proliferation of intraretinal capillaries originating from the deep retinal complex (intraretinal neovascularization [IRN]). Stage II was determined by growth of the retinal vessels into the subretinal space (subretinal neovascularization [SRN]). Stage III occurred when CNV could clearly be determined clinically or angiographically. A vascularized pigment epithelial detachment and RCA were inconsistent features of this stage. CONCLUSIONS: Retinal angiomatous proliferation appears to be a distinct subgroup of neovascular ARMD. It may present in one of three vasogenic stages: IRN, SRN, or CNV. Whereas ICG angiography is helpful in diagnosing RAP and in documenting the stage of the neovascularized process, it is frequently difficult to determine the precise nature and location of the new vessel formation. It is important for clinicians to recognize the vasogenic potential and the associated manifestations of this peculiar form of neovascular ARMD so that a proper diagnosis can be made, and when possible, an appropriate management administered.

Twenty-seven years follow-up of a patient with congenital retinocephalofacial vascular malformation syndrome and additional congenital malformations (Bonnet-Dechaume-Blanc syndrome or Wyburn-Mason syndrome).

PURPOSE: Follow-up of vascular changes in a patient with congenital retinocephalofacial vascular malformation syndrome. METHODS: MRI and cerebral angiography. RESULTS: In a 36-year-old man, magnetic resonance imaging of the skull and cerebral angiography revealed left intracranial arteriovenous malformations. Follow-up observation of 27 years revealed no essential change of retinal and cerebral arteriovenous malformations. Additional congenital deficits in this patient were described. CONCLUSION: Patients with retinal arteriovenous malformations should be early examined with neuroradiological methods.

Detection of Occult Arteriovenous Malformation With Annular Array Ultrasonography.

Retinal vascular tortuosity may occur in a wide range of ocular disorders. When retinal vascular tortuosity involves both arteries and veins, and presents unilaterally and without hemorrhage, a diagnosis of Wyburn Mason syndrome (WMS) should be considered due to the potential morbidity and mortality associated with cerebral involvement. Magnetic resonance imaging (MRI) and MRI angiography (MRA) are important tools for identifying cerebral arteriovenous malformations (AVMs), but these imaging modalities have limited spatial resolution to detect very small vascular lesions. Annular array contact ocular ultrasound is a new imaging modality capable of detecting small intraorbital AVMs. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:239-243.].

Retinal Arteriovenous Malformation Occlusion and Optic Nerve Drusen: Casuality or Causality?

Multimodal imaging of an impending retinal vein occlusion in an arteriovenous malformation associated with optic nerve drusen (OND) in a 16-year-old girl affected by Wyburn-Mason Syndrome. The authors seek to determine whether the association between the two entities has had an additive role in the acute retinal vascular event. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:418-419.].

The Oxygen Saturation in Vascular Abnormalities Depends on the Extent of Arteriovenous Shunting in Diabetic Retinopathy.

Purpose: Diabetic retinopathy is characterized by disturbances in retinal blood flow mediated by capillary occlusion, intraretinal microvascular abnormalities (IRMAs), neovascularizations, and omega loops and reduplications. It is likely that the study of oxygen saturation in these abnormalities can provide knowledge about their role in the development of diabetic retinopathy. Methods: The oxygen saturation in IRMA vessels and venous loops and reduplications were studied in 40 diabetic patients with severe nonproliferative or proliferative diabetic retinopathy. The saturation values in the studied vascular abnormalities were compared to those of the larger retinal arterioles and venules. Results: There was a similar oxygen saturation (mean ± SD) in IRMAs observed to connect arterioles with venules (78.6% ± 11.8%, n = 22) and IRMAs connecting venules with venules (79.2% ± 9.0%, n = 12; P > 0.999). The saturation in IRMAs was significantly lower (P < 0.0002) than in arterioles (97.4% ± 5.2%, n = 40) and significantly higher (P < 0.0001) than the saturation in omega loops and reduplications (54.2% ± 19.3%, n = 6), which in turn showed no significant difference from the saturation in the venules (61.8% ± 6.8%, n = 40, P = 0.4). Conclusions: The findings suggest that the oxygen saturation in vascular abnormalities in diabetic retinopathy depends on the extent of arteriovenous (A-V) shunting, with venous saturation due to no A-V shunting in venous loops and reduplications, and intermediate oxygen saturation due to moderate shunting in IRMAs. This may precede the development of neovascularizations with arterial oxygen saturation due to high A-V shunting.

The congenital unilateral retinocephalic vascular malformation syndrome (bonnet-dechaume-blanc syndrome or wyburn-mason syndrome): review of the literature.

Retinal arteriovenous malformations represent a rare syndrome in which a direct connection of major vessels without interposition of capillaries may lead to various complications such as thrombosis and vessel occlusion. This review comprises the computer-stored data of all the 121 patients with arteriovenous malformations described in the literature. Twenty-seven patients had typical Bonnet-Dechaume-Blanc syndrome (in this article designated as congenital retinocephalofacial vascular malformation syndrome), 25 had incomplete congenital retinocephalofacial vascular malformation syndrome (without facial skin lesions), 57 had isolated retinal arteriovenous malformations, and 12 had arteriovenous communications of the retina and distinct neurological signs, but without neuroradiological evidence of cerebral arteriovenous malformations (presumed cerebral arteriovenous malformations). Concerning the retinal findings, we found a distinct difference by comparing patients with congenital retinocephalofacial vascular malformation syndrome and those with isolated retinopathy without cerebral or facial malformations: extensive retinal malformations of vessels of most parts of the fundus occurred conspicuously more often in patients with retinal and cerebral arteriovenous malformations. In contrast, local retinal arteriovenous malformations occurred in all patients with isolated retinopathy without cerebral or facial malformations and rarely in patients with congenital retinocephalofacial vascular malformation syndrome. In conclusion, patients with arteriovenous communications of the retina should be examined early with brain and orbital neuroimaging to rule out cerebral arteriovenous malformations. Current therapeutic strategies include endovascular, surgical, and radiation procedures.

Unilateral retinal venous beading.

Inherited retinal venous beading is a rare retinal vascular disorder that is characterised by tortuosity and beading of the retinal veins. This can potentially lead to vision-threatening complications such as vitreous haemorrhage, macular hard exudation and ischaemia. We report a case of sporadic unilateral retinal venous beading in an 18-year-old white man who was referred by his optician following a routine eye examination. This malformation was unilateral and did not involve any other ocular structure. He had no associated ocular or systemic disorders. When last seen, he did not have any visual complications due to this vascular anomaly.

Congenital Retinal Macrovessel and the Association of Retinal Venous Malformations With Venous Malformations of the Brain.

Importance: Congenital retinal macrovessel (CRM) is a rarely reported venous malformation of the retina that is associated with venous anomalies of the brain. Objective: To study the multimodal imaging findings of a series of eyes with congenital retinal macrovessel and describe the systemic associations. Design, Setting, and Participants: In this cross-sectional multicenter study, medical records were retrospectively reviewed from 7 different retina clinics worldwide over a 10-year period (2007-2017). Patients with CRM, defined as an abnormal, large, macular vessel with a vascular distribution above and below the horizontal raphe, were identified. Data were analyzed from December 2016 to August 2017. Main Outcomes and Measures: Clinical information and multimodal retinal imaging findings were collected and studied. Pertinent systemic information, including brain magnetic resonance imaging findings, was also noted if available. Results: Of the 49 included patients, 32 (65%) were female, and the mean (SD) age at onset was 44.0 (20.9) years. A total of 49 eyes from 49 patients were studied. Macrovessel was unilateral in all patients. Color fundus photography illustrated a large aberrant dilated and tortuous retinal vein in all patients. Early-phase frames of fluorescein angiography further confirmed the venous nature of the macrovessel in 40 of 40 eyes. Optical coherence tomography angiography, available in 17 eyes (35%), displayed microvascular capillary abnormalities around the CRM, which were more evident in the deep capillary plexus. Of the 49 patients with CRM, 39 (80%) did not illustrate any evidence of ophthalmic complications. Ten patients (20%) presented with retinal complications, typically an incidental association with CRM. Twelve patients (24%) were noted to have venous malformations of the brain with associated magnetic resonance imaging. Of these, location of the venous anomaly in the brain was ipsilateral to the CRM in 10 patients (83%) and contralateral in 2 patients (17%), mainly located in the frontal lobe in 9 patients (75%). Conclusions and Relevance: Our study has identified an association between macrovessels in the retina and venous anomalies of the brain (24% compared with 0.2% to 6.0% in the normal population). Thus, we recommend new guidelines for the systemic workup of patients with CRM to include brain magnetic resonance imaging with contrast. These lesions may be more accurately referred to as retinal venous malformations, which may raise awareness regarding potential cerebral associations.