Retinal disease macular

The FDA approved intraocular injections include miotics, triamcinolone acetonide, pegaptanib sodium, ranibizumab, formivirsen sodium, viscoelastics and viscoadherents, and an antiviral agent for intravitreal injection. There are many small and large molecules currently in clinical trials that are delivered via intravitreal injection for the treatment of a variety of retinal diseases with a large area of focus on the treatment of AMD and macular edema. 

As described below, microdialysis probes have been used to deliver therapeutic concentrations of drugs that may be useful to treat a variety of retinal diseases (50 52). Drugs that target macular edema, syphilis, CMV retinitis, proliferative vitreoretinopathy and retinal degenerative diseases have been tested. However, treatment for other conditions with this approach, particularly intraocular malignancy, could be envisioned. 

Bevacizumab has been studied in advanced carcinoid tumors [167 ], prostate cancer [168 ], high-risk corneal transplantation [169 ], diabetic retinopathy [170 , 171, 172 ], ischemic retinal diseases [173 ], refractory choroidal neovascularization secondary to uveitis [174 ], macular edema secondary to branch retinal vein occlusion [175 ], retinal angiomatous proliferation [176% choroidal neovascularization attributable to pathological myopia [177, 178], exudative age-related macular degeneration [179 ], multifocal lymphangioendothe-liomatosis with thrombocytopenia [180" ], in combination with chemotherapy for the treatment of recurrent ovarian cancer [181 j, advanced melanoma [182 ], malignant pleural mesothelioma [183 ],... 

The most frequent cause of vision loss in the elderly is macular degeneration. Mild forms of the disease occur in nearly 30% of those over 75 years of age and more serious forms in 7% of that age group. There are many causes, some hereditary.555 5563 Excessive accumulation of fluorescent lipofuchsin, perhaps arising in part from Schiff base formation between retinal and phosphatidylethanolamine, is sometimes observed.557... 

Pathologic neovascularization of the retina is central to several debilitating ocular diseases including proliferative diabetic retinopathy (PDR), age-related macular degeneration (AMD), and retinopathy of prematurity (ROP). Diabetic retinopathy (primarily retinal NV) and the wet form of AMD (primarily choroidal NY) are the leading causes of blindness in developed countries. 

Disorders of the posterior segment of the eye are particularly difficult to treat. The efficient clearance mechanisms at the front of the eye reduce the concentrations of drug able to diffuse to the back of the eye. Futhermore, many of these disorders are chronic conditions, requiring continuous therapy. The diseases of the back of the eye include Cytomeaglovirus retinits (CMVR), Proliferative vitreoretinopathy (PVR), diabetic retinopathy, age-rated macular degeneration, endophthalmitis and retinitis pigmentosa. 

Fig. 5 L OCT image of 6 mm of the macular retinal layers of a 46-year-old healthy subject with an lOP 15 mmHg and Snellen visual acuity 20/20. Right OCT image of 6 mm of the macular retinal layers of a 50-year-old, moderately advanced (Hoehn and Yahr staging 2.5) PD patient (Unified Parkinsons Disease Rating System motor score 17) prior to any anti-Parkinsonian treatment. lOP was 14 mmHg and Snellen visual acuity 20/25 (from Hajee et al., 2009)...

An additional clinical use of acetazolamide is unrelated to its ocular hypotensive properties.The 500-mg acetazolamide capsule administered daily for 2 weeks may produce either a partial or a complete resolution of macular edema in patients with cystoid macular edema (CME), retinitis pigmentosa, and chronic intermediate uveitis (pars planitis). Macular edema produced by primary retinal vascular diseases (branch and central retinal vein occlusion and macular telangiectasia) did not respond to acetazolamide therapy. It is believed that acetazolamide may improve visual function if the macular edema stems from retinal pigment epithelial dysfunction. Improved macular edema in these conditions may be associated with fluid movement from the retina to the choroid. However, acetazolamide does not appear to alter macular blood flow. 

Several extended-release devices able to deliver a consistent level of corticosteroid to the retina have been devised. Two will be presented in this chapter, although other devices are under evaluation or in the development pipeline at the time of writing. The primary indications for these devices are persistent macular edema associated with several conditions, including diabetic retinopathy, retinal vascular occlusive disease, cataract surgery, and posterior uveitis. 

Other rare complications that may lead to reduced visual acuity are subretinal pigment epithelial neovascularization, choroidal folds, preretinal macular hemorrhage, choroidal and subretinal hemorrhages, macular star formation, and retinal pigment epithelial disease. 

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