الفهرس 
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Abstract
Diabetic retinopathy (DR) can be a debilitating complication of diabetes mellitus (DM) and is a worldwide leading cause of blindness. Diabetic macular edema (DME) and various forms of optic neuropathy (ONP) are other ocular complications of diabetic patients.
An optic nerve head (ONH) is supplied by the posterior ciliary artery and central retinal artery. The radial peripapillary capillaries (RPC) as the main capillary bed are the most common capillaries located in the inner part of the nerve fiber layer around the ONH. Jia et al. have found that the relatively dense RPC spreads as far as 5.5 mm from the disc center.
Optical Coherence Tomography Angiography (OCTA) is a non-invasive quantitative technique used to examine retinal and peripapillary microvasculature. The development of OCTA has enabled visualization and quantification of the RPC and papillary vessels in various retinal vascular diseases such as DR.
Few previous studies reported some microvascular changes in ONH even in subclinical phase of the disease. It is shown that the density of the RPC and the thickness of the peripapillary retinal nerve fiber layer (PP-RNFL) were significantly reduced in subclinical DR relative to control subjects. So, the aim of this work was to measure vascular density of optic nerve head in diabetic retinopathy using optical coherence tomography angiography.
To elucidate our aim, this study was clinical trial control study included 76 eyes of both genders with diabetes mellitus and healthy matched sex and age at outpatient clinics of ophthalmology Department, Faculty of Medicine, Menoufia University, during the period of the study from October 2022 till May 2023.
All subjects included in this study were divided in to two groups as: group I (patients’ group): included 38 eyes of patients with diabetes mellitus and Group
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II (control group): included 38 healthy subjects matched age and sex.
All subjects included in this study were subjected to: Demographic information was obtained from each participant included age, sex, duration, and medication., Serum glycosylated hemoglobin (HbA1c) measured in all patients with DM to evaluate their glycemic status, Complete ophthalmological examination included best-corrected visual acuity (BCVA) measurement, Intraocular pressure (IOP), Slit-lamp examination and dilated fundoscopy, anterior and posterior segment examinations were part of the comprehensive ophthalmological examination, Visual acuity assessment by Snellen’s chart, anterior segment examination by slit-lamp bio.
The results of this study could be summarized as follow:
The visual acuity was significantly lower among eyes of cases (0.51±0.22) than controls eyes (0.79±0.21), (P<0.001). Moreover, HBA1c was significantly higher among eyes of cases (8.03±1.28) than controls eyes (4.73±0.48), (P<0.001).
Among cases, the most type of diabetic retinopathy was NDR (42.1%) then NPDR (36.8%) followed by PDR (21.1%). Furthermore, 50% of cases had diabetic macular edema vs 15.8% of controls (P=0.002). Also, 76.3% of cases had Hypertension Vs 13.2% of controls with reach to significant level (P<0.001).
There were no significant differences between eyes of cases and controls regarding RNFLT and inferior hemi density (P>0.05). While, whole image, inside disc, peripapillary and superior hemi significantly lower among eyes of cases (53.71±3.67, 56.40±5.79, 56.59±4.34, 57.21±4.47) than controls (57.22±2.19, 59.61±4.29, 59.06±1.93, 59.45±1.93), (P<0.05) respectively.
RNFLT was significantly decreased among NDR cases than controls, NPDR and PDR cases, (P=0.014). Moreover, whole image, peripapillary, superior hemi and inferior hemi significantly lower among NPDR patients than PDR,
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NDR cases and controls (P<0.05). Also, inside disc significantly lower among PDR cases than NPDR, NDR cases and controls (P=0.010).
There was a significant positive correlation between whole image with visual acuity, RNFLT and small RPC (whole image, inside disc, parapapillary, superior hemi, inferior hemi), (P<0.05). While, there was a significant negative correlation between whole image with type of diabetic retinopathy (P=0.004).
There was a significant negative correlation between inside disc with type of diabetic retinopathy (P=0.030). Also, there was a significant positive correlation between inside disc with RNFLT and small RPC (whole image, inside disc, peripapillary, superior hemi, inferior hemi), (P<0.05).