الفهرس 
? REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Summary Diabetes mellitus (DM) is a worldwide pandemic disease. As of 2010, more than 200 million people had been diagnosed with diabetes, and this number is predicted to increase by 62% by 2025. This increase is due to an increase in obesity together with the increased life expectancy of the world population. DM complications include macroangiopathy (myocardial infarction or vasculocerebral stroke) and microangiopathy (diabetic nephropathy, neuropathy, and retinopathy).
Diabetic Retinopathy is a progressive disease predominantly affects the integrity of the microscopic vessels found in the retina. Diabetic retinopathy can be broadly divided into two clinical stages: non proliferative and proliferative diabetic retinopathy. Proliferative diabetic retinopathy develops following the occlusion of retinal capillaries leading to retinal ischemia, which promotes the development of neovascularization, a process by which new blood vessels proliferate on the surface of the retina and these vessels are fragile and bleed easily. The resulting accumulation of blood in the vitreous cavity from these hemorrhaging vessels seriously impairs vision. This impairment of vision may be permanent due to further complications such as traction retinal detachment.
With the help of optical coherence tomography, it is now possible to measure the retinal layers thickness objectively and to follow the progression of diabetic retinopathy quantitatively. And periodic glycosylated hemoglobin measurements can reflect the long-term control of hyperglycaemia. Intensive glycemic control had been proved to be effective in decreasing incidence rate of development and progression of diabetic retinopathy in type 1 and type 2 diabetic mellitus as demonstrates by diabetes control and complication trials.
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We conducted our study to evaluate the macular nerve fiber layer and ganglion cell layer thickness comparing diabetic patients with normal healthy controls.
The study included 72 eyes of 36 patients with type 1 diabetes with no or minimal diabetic retinopathy and 72 eyes of 36 normal healthy controls. Patients have been recruited from outpatient clinic of Ain Shams University hospitals and asked to participate in this study. This study was designed as an observational, cross-sectional non-randomized study in the period from 8/2016 to 9/2017.
This study included only type 1 diabetic patients with no or minimal diabetic retinopathy. And we exclude from the study patients with proliferative diabetic retinopathy, age >30 and <10 years, corneal opacity, opaque lens, glaucoma, refraction more than +5 or -5, ocular surgery and Systemic diseases like hypertension, renal, hepatic and neurodegenerative diseases.
All subjects participating in the study asked to sign informed written consent before inclusion. Then they subjected to: full medical history, recent glycosylated haemoglobin level and complete ocular examination on the day of optical coherence tomography assessment included (best corrected visual acuity, intraocular pressure and dilated fundus examination).
Early mild non-proliferative DR is diagnosed as the presence of 2 or more micro-aneurysms and or minor hemorrhages in the central retina and a healthy peripheral retina determined by slit-lamp biomicroscopy with 90D lens or indirect ophthalmoscopy.
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Optical coherence tomography (NIDEK Optical Coherence Tomography RS-3000 Advance; Nidek, Japan. With The image filing software NAVIS-EX, RS-3000 Advance OCT) was used to evaluate macular nerve fiber layer and ganglion cell layer thickness. Using The MACULA RADIAL protocol evaluates 6 ×6 mm area centered on the fovea as possible. The patient’s fundus is scanned along equally spaced radial lines that intersect at the center of the macula to obtain OCT images.12 scan lines with each spaced 15 ° apart from each other. The Macula radial scan pattern evaluates a 6 × 6-mm area centered on the fovea with B-scan lines, each consisting of 1,024 A scans per line.
Retinal thickness was automatically calculated in the ETDRS (Early Treatment Diabetic Retinopathy Study) areas (consisting of 2 concentric rings inner and outer rings of 3 and 6 mm diameter, respectively). The inner and the outer rings are divided into four quadrants (nasal, superior, temporal and inferior quadrant).The mean thickness of targeted retinal layers in each of the ETDRS subfields was recorded. Retinal fiber layer (NFL) and ganglion cell layer (GCC) was calculated automatically in the Macula Radial protocol from the inner border of NFL to the outer border of GCL.
If any instrument error in the automatic segmentation of retinal layers was documented by the second examiner, the manual correction consisted in the repositioning into proper place of the incorrectly placed points (using high magnification images), in order to redefine the retinal profile.
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All data was collected and analyzed statistically.
The results showed that diabetic group and healthy control group were comparable in age, sex, and best corrected visual acuity.
The results of our study reported that there is no difference in nerve fiber layer and ganglion cell layer thickness in diabetic patients type 1 with no clinical diabetic retinopathy in early stages of the disease.
The results showed that there were decreased macular nerve fiber layer and ganglion cell layer thickness in diabetic cases in some zones and increased macular nerve fiber layer and ganglion cell layer thickness in diabetic cases in other zones which was clinically insignificant.
Optical coherence tomography is a sensitive and noninvasive diagnostic tool in the evaluation of macular nerve fiber layer and ganglion cell layer thickness in patients with type 1 diabetes.
The outcome of our study reported that there is no difference in nerve fiber layer and ganglion cell layer thickness in diabetic patients type 1 with no clinical diabetic retinopathy in early stages of the disease.