الفهرس 
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Abstract
Diabetes mellitus (DM) is a chronic condition that occurs when there are raised levels of glucose in the blood because the body cannot produce any or enough insulin or use insulin effectively. Hyperglycemia, if left unchecked over the long term, can cause damage to various body organs with life and vision-threatening health complications. Retinopathy is one of the long-term complications of the diabetes. A relationship between glycemic control and the HbA1c concentration was demonstrated. The ADA has recommended HbA1c as a substitute to FBG. HbA1c is an important indicator of cumulative glycemic history. HbA1c not only provides a reliable measure of chronic hyperglycemia but also correlates well with long-term diabetes complications such as retinopathy, nephropathy and neuropathy.
Diabetic retinopathy (DR) is a chronic progressive sight-threatening condition which has retinal microvascular and neuronal components. It is considered as the leading cause of visual loss in working-age populations. It was believed that the vision impairment that develops in diabetic patients was due to the vascular lesions that characterize the disease. It is becoming very clear that retinal neuronal cells are also affected by DM, resulting in degeneration and dysfunction of some neuronal cells. Retinal Nerve Fiber Layer and Retinal Ganglion Cells are the best studied of the retinal neurons with respect to the diabetes effect. In DR, many pathological cellular and molecular processes occur in the early stages of the disease and may inflict subtle changes on retinal function before retinopathy is anatomically evident. Many theories suggest that inflammation, oxidative stress and exposure to advanced glycation end products may contribute to those retinal pathologies, including ganglion cells apoptosis.
RNFL is formed from axons of the ganglion cells and the health of the Optic Nerve can be assessed by the evaluation of the RNFL which could be done via OCT or scanning laser polarimetry showing association of DM with thinning of the RNFL. GCC consists of the innermost 3 layers of the retina: The Retinal Nerve Fiber Layer (RNFL): composed of the axons, the Ganglion Cell Layer (GCL): composed of the cell bodies and the Inner Plexiform Layer (IPL): composed of the Retinal Ganglion Cells dendrites (RGC).
Our study included 30 patients,15 patients of uncontrolled diabetes who represents group 1 with “HbA1c ≥ 7% with 10 cases (66.7%) were males and 5 cases (33.3%) were females and 15 controlled diabetic group with HbA1c < 7% with 6 cases (40.0%) were males and 9 cases (60.0%) were females.
Patients’ age ranged 40-70 years, with the mean age of 53.53 +/-9.16 years in uncontrolled diabetes group, 54.80 +/-9.42 years in controlled diabetic group.
In uncontrolled group 1, RNFL parameters showed the mean average and temporal RNFL thickness is the right eye was lower compared to group 2 controlled patients also inferior RNFL is lower in this group in comparison the other in the right and left eyes.
On the other hand, GCC parameters were as follow: group 1 had a statistically significantly lower average and inferior GCC at the right eye compared to group 2 Conversely, FLV at left eye was a statistically significantly higher in group 1 than 2 and GLV in both eyes in the same group is higher.
Several studies have revealed a significant atrophy in RNFL and GCC layers and significant correlation between HbA1c with RNFL and GCC thickness while other studies could not find any significant correlation.
In our study, we found a significant correlation between HbA1c and average, superior and inferior RNFL in both eyes and nasal quadrant in the right eye in uncontrolled diabetics ≥ 9.3%. We also noticed, a negative significant correlation between HbA1c with average, superior and inferior GCC in both eyes in group 1. And, positive statistically significant correlations between HbA1C with average inferior GCC in left eye may be within normal limits or due to very mild clinically non-evident disc oedema in controlled diabetic group 2. For FLV and GLV, it was positively correlated with FLV and GLV both eyes in controlled diabetic group and become positively significant correlated with FLV only in uncontrolled group.
Patients with uncontrolled diabetes have significant correlation between HbA1c and some quadrants of RNFL and GCC especially patients with (HbA1c ≥ 9.3%) than controlled diabetic patients, which is a novel finding. It is recommended to use RNFL and GCC thickness (Neuro-retinal thickness) as an early predictive marker of retinopathy development and complications by using OCT Optic disc in the routine examination of the diabetic patients.