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Retinal Photocoagulation (retinal + photocoagulation)
Selected Abstracts2414: Laser and vitrectomyACTA OPHTHALMOLOGICA, Issue 2010E STEFANSSON Purpose Modern vitreous surgery involves a variety of treatment options in addition to vitrectomy itself, such as photocoagulation, anti-VEGF drugs, intravitreal steroids and release of vitreoretinal traction. A full understanding of these treatment modalities allows sensible combination of treatment options. Methods Vitrectomy reduces the risk of retinal neovascularization, while increasing the risk of iris neovascularization, reduces macular edema and stimulates cataract formation. These clinical consequences may be understood with the help of classical laws of physics and physiology. The laws of Fick, Stokes-Einstein and Hagen-Poiseuille state that molecular transport by diffusion or convection is inversely related to the viscosity of the medium. When the vitreous gel is replaced with less viscous saline, the transport of all molecules, including oxygen and cytokines, is facilitated. Oxygen transport to ischemic retinal areas is improved, as is clearance of VEGF and other cytokines from these areas, thus reducing edema and neovascularization. At the same time, oxygen is transported faster down a concentration gradient from the anterior to the posterior segment, while VEGF moves in the opposite direction, making the anterior segment less oxygenated and with more VEGF, stimulating iris neovascularization. Results Retinal photocoagulation has also repeatedly been shown to improve retinal oxygenation. Oxygen naturally reduces VEGF production and improves retinal hemodynamics. The VEGF-lowering effect of photocoagulation and vitrectomy can be augmented with anti-VEGF drugs and the permeability effect of VEGF reduced with corticosteroids Conclusion Vitrectomy and laser retinal treatment both improve oxygenation of the ischemic retina, reduce VEGF formation and thereby reduce neovascularisation and edema. [source] Retinal photocoagulation and oxygenationACTA OPHTHALMOLOGICA, Issue 2009CJ POURNARAS Purpose The clinical role of photocoagulation for the treatment of hypoxia related complications of retinal ischemic microangiopathies is well established. Methods Measurements of the partial pressure of oxygen (PO2) distribution within the the retina in various animal species using oxygen sensitive microelectrodes and evaluation of the retinal vessels reactivity by laser doppler velocimetry gave additional insights concerning photocoagulation mechanisms. Results The PO2 within the vitreo-retinal interface is heterogeneous. Preretinal and trans-retinal PO2 profiles indicate that the preretinal PO2 far away from vessels remain constant in all retinal areas. Intervascular intraretinal PO2 gradually decreases from both the vitreo-retinal interface and the choroid towards the mid-retina. Close to the pigment epithelium, it is significantly higher than at the vitreoretinal interface due to the much higher O2 supply provided by choroidal compaires to retinal circulation. Laser photocoagulation reduces the outer retina O2 consumption and allows O2 diffusion into the inner retina from the choroid raising the PO2 in the inner healthy retinal layers and in the preretinal intervascular normal areas. In this way laser treatment relieves retinal hypoxia in experimental branch vein occlusion (BRVO). In patients with diabetic retinopathy (DR), the retinal PO2 is higher in areas previously treated with laser. Following photocoagulation, the resulting reversal of hypoxia, the retinal vasculature constriction and the improvement of the regulatory response to hyperoxia all affect favorably both the retinal neovascularisation and macular edema. Conclusion Photocoagulation induces an increase of the inner retinal oxygenation reversing the retinal hypoxia and improving the regulatory response of the retinal vessels [source] 2411: Clinical effect of retinal photocoagulationACTA OPHTHALMOLOGICA, Issue 2010F BANDELLO [source] Intravitreal anti-vascular endothelial growth factor therapy with bevacizumab for tuberous sclerosis with macular oedemaACTA OPHTHALMOLOGICA, Issue 3 2010Wataru Saito Abstract. Purpose:, To describe two patients with macular oedema secondary to tuberous sclerosis complex (TSC) who were treated with intravitreal bevacizumab injection. Methods:, Interventional case reports. Bevacizumab 1.25 mg was injected into the vitreous of two patients with TSC-associated macular oedema / exudative retinal detachment. Vascular endothelial growth factor (VEGF) concentration in the vitreous fluid was measured by enzyme-linked immunosorbent assay (ELISA) in one of these patients. Results:, Patient 1: a 22-year-old woman with TSC was diagnosed as having multiple retinal hamartomas in both eyes. Eleven years later, the patient developed macular oedema with epiretinal membrane formation in the right eye. The patient underwent pars-plana vitrectomy with retinal photocoagulation for retinal tumours. VEGF concentration in the vitreous fluid was high compared to that in patients without retinal vascular diseases. Recurrent macular oedema disappeared by intravitreal injection of bevacizumab. Patient 2: a 32-year-old woman with TSC-associated retinal hamartoma, temporally showing macular exudative retinal detachment, developed neovascularization originated from the tumour. By intravitreal bevacizumab injection, the tumour size reduced markedly with regression of neovascularization. Conclusion:, These results suggest that VEGF derived from retinal hamartomas causes macular oedema associated with TSC. Intravitreal injections of bevacizumab may be a useful therapeutic option for macular oedema secondary to TSC. [source] A new technique for diode laser cyclophotocoagulation: short term resultsACTA OPHTHALMOLOGICA, Issue 2009M SURIANO Purpose To evaluate the efficacy of a new technique for diode laser cyclophotocoagulation in refractory glaucoma. Methods A consecutive case series of 8 eyes of 7 Caucasian patients who underwent gonioprism assisted diode laser cyclophotocoagulation (GADC). GADC with a peripheral corneal approach is a new surgical technique that employs a manual gonioprism, iris hooks, ophthalmic operating microscope and an 810 nm laser diode probe usually utilized for retinal photocoagulation Results The mean follow-up time was 5.9 months (range 3 to 11 months). Mean intraocular pressure (IOP) (±SD) was reduced from 24.5±4.3 mmHg to 11.25±1.7 mmHg. The mean number of IOP lowering eye drops (±SD) was reduced from 2.0±0.8 preoperatively to 0.8±0.5 postoperatively. The visual acuity remained unchanged in 7 of 8 eyes (87.5%) and deteriorated in 1 of 8 eyes (12.5%). Early complications included IOP spike in one patient. No major complications were encountered. No eyes required repeat cyclophotocoagulation. Conclusion Gonioprism assisted diode laser cyclophotocoagulation with peripheral corneal approach appears to be an effective and safe surgical treatment of refractory glaucoma and has the advantage of no requiring of new endoscopic devices. [source] The therapeutic effects of retinal laser treatment and vitrectomy.ACTA OPHTHALMOLOGICA, Issue 5 2001A theory based on oxygen, vascular physiology ABSTRACT. The physiologic mechanism of photocoagulation can been seen in the following steps. The physical light energy is absorbed in the melanin of the retinal pigment epithelium. The adjacent photoreceptors are destroyed and are replaced by a glial scar and the oxygen consumption of the outer retina is reduced. Oxygen that normally diffuses from the choriocapillaris into the retina can now diffuse through the laser scars in the photoreceptor layer without being consumed in the mitochondria of the photoreceptors. This oxygen flux reaches the inner retina to relieve inner retinal hypoxia and raise the oxygen tension. As a result, the retinal arteries constrict and the bloodflow decreases. Hypoxia relief reduces production of growth factors such as VEGF and neovascularization is reduced or stopped. Vasoconstriction increases arteriolar resistance, decreases hydrostatic pressure in capillaries and venules and reduces edema formation according to Starling's law. Vitrectomy also improves retinal oxygenation by allowing oxygen and other nutrients to be transported in water currents in the vitreous cavity from well oxygenated to ischemic areas of the retina. Vitrectomy and retinal photocoagulation both improve retinal oxygenation and both reduce diabetic macular edema and retinal neovascularization. [source] Intravitreal bevacizumab (Avastin) as a treatment of the neovascular complications of laser-induced chorioretinal anastomosis for nonischaemic central retinal vein occlusionCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 5 2009Kenneth C S Fong FRCOphth Abstract Purpose:, To describe the use of intravitreal bevacizumab followed by sectorial retinal photocoagulation to treat the neovascular complications of laser-induced chorioretinal anastomosis (L-CRA) for nonischaemic central retinal vein occlusion (CRVO). Methods:, Prospective interventional case series of three patients with nonischaemic CRVO who were treated with L-CRA. Patients were followed up every 2 weeks after the laser treatment. If neovascularization occurred at the site of the anastomosis, intravitreal bevacizumab (1.25 mg) was injected followed by laser photocoagulation to areas of retinal ischaemia and the area of retina anterior to the L-CRA 1 week later. Fluorescein angiography was performed to confirm the presence of neovascularization. Best-corrected visual acuity measurements were performed at every visit. Results:, Three patients (one woman, two men) with a mean age of 76.3 years developed neovascularization at the L-CRA site and underwent treatment as described with a mean follow-up time of 7 months. The neovascularization developed within 1 month after the laser anastomosis in all three cases. All patients only required one intravitreal bevacizumab injection to control the neovascularization. No complications of the intravitreal injections were noted. Conclusions:, Intravitreal bevacizumab appears to be an effective tool in the immediate control of neovascularization following L-CRA for nonischaemic CRVO. This appears to cause immediate regression of the neovascular frond and allows time for the laser, which is applied subsequently to have its effect. [source] | ||||||||||