الفهرس 
Acknowledgements
Prevalence of diabetic retinopathyOnly 14 pages are availabe for public view
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Abstract
Diabetic retinopathy (DR) is one of the serious complications of diabetes mellitus. Diabetic retinopathy impacts the vision significantly and accounts for about 20% of visual impairment in working aged adults(2). DR is the leading cause of blindness around the world (3). PRP remains the gold standard treatment for proliferative diabetic retinopathy (PDR) Panretinal photocoagulation (PRP) reduces the risk of severe visual loss by 50% in patients with diabetic retinopathy. PRP is a procedure involve applying laser burns to the peripheral retina, from which the thermal energy induces tissue coagulation. Laser photocoagulation is a procedure in which, the laser light is absorbed primarily by melanosomes within the retinal pigment epithelium (RPE) ,where light energy is used to coagulate tissue ,by increasing tissue temperature, vaporization of liquids, denaturation of protein resulting in apoptosis. The coagulative effect mostly affects the outer retina, but also several studies have demonstrated a detrimental effect from PRP on adjacent tissues including the RNFL.PRP is theorized to stop the progression of ischemic disease by improving retinal oxygenation and decreasing the drive for vascular endothelial growth factor (VEGF) production by the retina. PRP reduces the risk of visual loss at the expense of other visual functions.Through the destruction of the peripheral neuronal retina, PRP causes significant visual side-effects, such as Constriction of visual field,Loss of dark adaptation and decrease in night vision after PRP treatment because of pathophysiology of chronic peripheral non-perfusion, which can lead to diminished rod function and subsequent changes in dark adaptation. Over time, ganglion cell damage can lead to reduced RNFLT and peripapillary RNFL thinning. Retinal nerve fiber layer (RNFL) thickness has been shown to be affected by PRP and appropriate titration of intensity should aim to achieve photocoagulation of the outer retina while limiting damage to the ganglion cells . Peripapillary RNFL can be measured by optical coherence tomography (OCT) Which is a non invasive technique for obtaining high-resolution, cross-sectional tomographic images of tissue by measuring backscattered light.. The advantage of OCT imaging is its high resolution. The ability to make repeatable, high-resolution measurements of the retina with good image quality is important for the diagnosis, follow-up and treatment of diabetic retinopathyThe Early Treatment Diabetic Retinopathy Study (ETDRS) recommends application of up to 2000 visible end-point burns on the retina. It is recognized that the laser scar expansion in the retina may be associated with photoreceptor loss, RPE hypertrophy, and visual field loss. The annual scar expansion rate (16.5%) continues to increase up to 4 years after PRP.