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.

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.].

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.].

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.

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.

Corkscrew retinal vessels and retinal arterial macroaneurysm in a patient with neurofibromatosis type 1: A case report.

RATIONALE: Neurofibromatosis type I (NF-1) is a multisystem autosomal dominant disease characterized by pigmentation and the growth of tumors along nerves in the skin, brain, and other parts of the body. It is caused by a mutation in the NF-1 tumor suppressor gene. NF-1 vascular disease is an important complication of the disease. PATIENT CONCERNS: The study reports a unique case of a patient with NF-1 with 2 simultaneous vascular abnormalities, involving tiny spiral venous changes (corkscrew retinal vessels) and retinal arterial macroaneurysms. Our patient was diagnosed with NF-1 as she met the following National Institutes of Health consensus criteria for the diagnosis of NF-1: more than 6 cafe au lait macules, of a maximum diameter ≥15mm, 2 neurofibromas within the dermis, and Lisch nodules on the iris. DIAGNOSES: Retinal arterial macroaneurysm in the left eye, corkscrew retinal vessels related to NF-1 and Neurofibromatosis type I. INTERVENTIONS: Due to the possibility of automatic involution of macroaneurysms, recovery may not affect vision (4). A cardiologist advised the patient to take nifedipine tablets (30mg/d) to treat her high blood pressure while continuing observation of the macroaneurysms. OUTCOMES: Preretinal, intraretinal, and subretinal hemorrhage near the retinal artery aneurysm in the patient showed partial absorption at 3 months of follow-up. LESSONS: Our analysis suggests that retinal macroaneurysm formed in the patient's body are due to neurofibroma type I secondary hypertension. The case study also indicated the symptoms of newly discovered neurofibroma type I which led to retinal microvascular abnormalities. We believe that such changes in eye blood vessels are rare and this case provides an insight to the field of neurology and ophthalmology.

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.