الفهرس 
Pathogenesis of Diabetic Macular Edema
A. BLOOD RETINAL BARRIEROnly 14 pages are availabe for public view
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Abstract
Diabetic macular edema (DME) is the most common ocular complication of diabetes mellitus and presents a serious visual threat to patients.
Diabetic macular edema is defined as retinal thickening within two disc diameters of the center of the macula.
Chronic hyperglycemia is the metabolic hallmark of diabetes and leads to widespread cellular damage. Endothelial cells are particularly vulnerable to hyperglycemia because they cannot regulate intracellular glucose. An excess of glucose sets off a chain of metabolic events that lead to the overproduction of reactive oxygen species and free radicals in the mitochondria (oxidative stress) and in turn, leads to an increased flux in the hexosamine and polyol pathways, increased formation of advanced glycation end products and activation of protein kinase C.
The only proven treatment of diabetic macular edema not due to vitreous traction consists of focal laser photocoagulation and is based on the results of the ETDRS. However, the visual prognosis after photocoagulation was worse when it was used to treat diffuse macular edema. The poor results of laser photocoagulation in several studies have prompted an interest in finding other treatments, including vitrectomy and pharmacological therapy.
TA is a long acting steroid which decreases DME when injected via the intravitreal or subtenon route due to its known anti-angiogenic, anti-edematous, anti-inflammatory, and anti-proliferative effects.
In this study we found that IVTA improved the CMT in 76.5% of patients, while STTA improved the CMT in 75% of patients.
The percentage of patients who showed an improvement in VA at the end of the follow up period was 60% in the IVTA group and 65% in the STTA group.
IVTA caused a higher rise in IOP than STTA, and the IVTA group showed 4 cases of secondary glaucoma.
The rate of complications was higher in the IVTA group, cataract 16%, secondary Glaucoma 21%, endophthalmitis 5%. In the STTA group only cataract was noticed in 10% of the patients.
Fluorescein angiography of both groups showed a close correlation between the improvement in CMT by OCT and the improvement in the fundus fluorescein picture as regards leakage.
It can be concluded that STTA injection is comparable to IVTA injection in the treatment of DME.