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Results for “Retinal Neovascularization”

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At least 667 records · Page 37Linked to original sources
PubMed2006

Focal laser ablation of retinal angiomatous proliferation.

PURPOSE: To evaluate the feasibility of focal laser ablation of retinal angiomatous proliferation (RAP) identified with clinical examination and high-speed indocyanine green (ICG) imaging in patients with age-related macular degeneration. METHODS: In this retrospective, interventional case series, 16 consecutive eyes of 15 patients with macular degeneration and leakage from a stage I or II RAP lesion were identified. RAP lesions were identified using clinical examination and high-speed ICG imaging. High-speed ICG imaging was used to identify the intraretinal component of the lesion. RAP lesions were treated with a 100- to 200-mum green or yellow wavelength laser spot that was applied to completely ablate the intraretinal component of the lesion. In eyes with stage II lesions, the subretinal component of the lesion was not treated. Early Treatment of Diabetic Retinopathy Study visual acuity, optical coherence tomography retinal thickness, angiographic leakage, and progression of the angiomatous process shown by ICG imaging were evaluated preoperatively and postoperatively. RESULTS: Sixteen eyes underwent successful ablation of the RAP lesions with an average of 1.9 treatment sessions. At a mean follow-up of 15.5 months, 94% of eyes had stable or improved visual acuity. Only 6% of eyes had a loss of >or=3 lines of visual acuity. The average visual acuity at the last follow-up was 20/45 in the stage I lesion group and 20/160 in the stage II lesion group. Of the patients, 87.5% had a reduction in retinal edema and subretinal fluid, with 69% of patients having complete resolution of retinal edema and subretinal fluid; 14% of patients had progression to retinal choroidal anastomoses. No treatment complications were encountered. CONCLUSION: Focal laser photocoagulation of RAP lesions appears to be feasible. This treatment appears to be a safe method of managing the leakage from RAP. Treatment of solely the intraretinal component of the lesion may be adequate to control leakage. Treatment may allow the angiomatous process to be arrested, resulting in stabilization of visual acuity. Visual acuity results appear to be better for patients with early stage lesions.

Aged, 80 and over↗
PubMed1990

Interaction of retinal pericytes, capillary endothelial cells and pigment epithelial cells in vasoproliferative retinopathies.

Degeneration of intramural pericytes is the first histopathological lesion seen in diabetic retinopathy. Since pericytes from the optic nerve and brain are spared, such degeneration appears to be specific to the retinal circulation. Recent studies have shown that when retinal pericytes and microvascular endothelial cells are co-cultured in vitro, direct contact between the two types of cells leads to the inhibition of proliferation of endothelial cells. Previously it was shown that when pericytes are cultured in the absence of microvascular endothelial cells, the cultured medium conditioned by the pericytes is actively mitogenic for retinal capillary endothelial cells. Furthermore, conditioned medium from human retinal pigment epithelial cells is also mitogenic for retinal capillary endothelial cells and pericytes. On the basis of these results, a new working hypothesis is proposed for the mechanism of action of photocoagulation used in vasoproliferative retinopathies.

Capillaries↗
PubMed1985

Macular recovery time recorded by nyctometry--a screening method for selection of patients who are at risk of developing proliferative diabetic retinopathy. Results of a 5-year follow-up.

A 5-year study on the predictive value of the macular recovery time, as recorded by nyctometry, in the development of proliferative diabetic retinopathy in insulin-dependent diabetes mellitus has been completed. Seventy-seven patients with a median age of 30,8 years and a median duration of the disease of 15,8 years participated. In the follow-up period, 16 out of 20 patients initially showing abnormally prolonged macular recovery time had developed proliferative diabetic retinopathy the median duration from the initial investigation to the diagnosis of retinal neovascularization being 34 months. Contrary to this finding, only 4 out of 57 patients initially showing normal macular recovery had advanced into proliferative retinopathy, and the median duration until diagnosis of this condition was 45 months. It is concluded that nyctometry can serve as an easily performed screening method in selecting those at risk of developing proliferative retinopathy within a few years.

Adolescent↗
PubMed2005

Angiopoietin concentrations in diabetic retinopathy.

BACKGROUND/AIM: Angiopoietin 1 and 2 interact with vascular endothelial growth factor (VEGF) to promote angiogenesis in animal and in vitro models. Although VEGF concentrations are elevated, there is little information regarding angiopoietin concentration in the vitreous of patients with diabetic retinopathy. METHODS: Angiopoietin concentrations were measured by luminescence immunoassay in vitreous samples from 17 patients with non-proliferative diabetic retinopathy (NPDR) and clinically significant diabetic macular oedema (CSMO), 10 patients with proliferative diabetic retinopathy (PDR), and five patients with macular hole (controls) obtained at pars plana vitrectomy. RESULTS: Angiopoietin 1 concentrations were low in patients with macular hole (median 17 pg/ml) while in NPDR with CSMO they were 2002 pg/ml (range 289-5820 pg/ml) and in PDR 186 pg/ml (range 26-2292 pg/ml). Angiopoietin 2 concentrations in NPDR with CSMO were a median of 4000 pg/ml (range 1341-14 329 pg/ml). For both macular hole and PDR patients angiopoietin 2 was below the limit of detection. CONCLUSIONS: Angiopoietin 2 concentration was twice that of angiopoietin 1 in NPDR with CSMO. Angiopoietin 2 is the natural antagonist of angiopoietin 1 which is thought to act as an anti-permeability agent. The predominance of angiopoietin 2 may allow VEGF induced retinal vascular permeability in patients with CSMO. The relatively low concentration of both angiopoietin 1 and 2 in patients with proliferative diabetic retinopathy may reflect the established nature of the neovascularisation in cases proceeding to vitrectomy.

Adult↗
PubMed2005

Generation of transgenic mice with mild and severe retinal neovascularisation.

AIM: To generate a mouse model for slow progressive retinal neovascularisation through vascular endothelial growth factor (VEGF) upregulation. METHODS: Transgenic mice were generated via microinjection of a DNA construct containing the human VEGF165 (hVEGF) gene driven by a truncated mouse rhodopsin promoter. Mouse eyes were characterised clinically and histologically and ocular hVEGF levels assayed by ELISA. RESULTS: One transgenic line expressing low hVEGF levels showed mild clinical changes such as focal fluorescein leakage, microaneurysms, venous tortuosity, capillary non-perfusion and minor neovascularisation, which remained stable up to 3 months postnatal. Histologically, there were some disturbance and thinning of inner and outer nuclear layers, with occasional focal areas of neovascularisation. By contrast, three other lines expressing high hVEGF levels presented with concomitantly severe phenotypes. In addition to the above, clinical features included extensive neovascularisation, haemorrhage, and retinal detachment; histologically, focal to extensive areas of neovascularisation associated with retinal folds, cell loss in the inner and outer nuclear layers, and partial retinal detachment were common. CONCLUSIONS: The authors generated four hVEGF overexpressing transgenic mouse lines with phenotypes ranging from mild to severe neovascularisation. These models are a valuable research tool to study excess VEGF related molecular and cellular changes and provide additional opportunities to test anti-angiogenic therapies.

Animals↗
PubMed2005

Spare the rod and spoil the eye.

This review presents a new unified view of the pathogenesis of three common causes of acquired retinal degenerative disease-diabetic retinopathy, age related macular degeneration, and retinopathy of prematurity. In these three conditions, angiogenesis has a predominant role in the development of sight threatening pathology. Angiogenesis is controlled by among other factors the expression of vascular endothelial growth factor (VEGF), which in turn is regulated by absolute and relative lack of oxygen. The severe pathological manifestations of these three conditions are not part of a general underlying disease process because they are peculiar to the eye, and the profound hypoxia that develops in normal retina during dark adaptation (rod driven hypoxia) is an adequate and elegant additional factor to explain their pathogenesis. A large number of experimental reports support this conclusion, although rod driven anoxia is not generally considered as a causal factor in ocular disease. However, the hypothesis can be critically tested, and also suggests novel methods of treatment and prevention of these conditions that may be simpler and more inexpensive than current therapies and that have a smaller potential for adverse effects.

Animals↗
PubMed1991

Course of diabetic retinopathy following cataract surgery.

Five patients with mild to moderate retinopathy to both eyes underwent complication-free cataract surgery in one eye. Within three months of surgery deterioration of the retinopathy was observed in the operated eye only. In four patients there was an increase of intraretinal haemorrhages and hard exudates, accompanied by clinically significant macular oedema manifested as retinal thickening and extensive fluorescein leakage from both the macular and the peripapillary capillary networks. Of these four patients one also developed retinal ischaemia, evident ophthalmoscopically by flame-shaped haemorrhages and cotton-wool spots and angiographically by areas of capillary non-perfusion. The fifth patient showed proliferation of new blood vessels and vitreous haemorrhage. Diabetic patients scheduled for cataract surgery should undergo a thorough preoperative evaluation of any existing retinopathy. Postoperatively they should be followed up at close intervals so that any progression of retinopathy can be promptly detected and considered for laser treatment.

Aged↗