الفهرس 
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Abstract
Diabetic eye disease, a complication of diabetes mellitus (DM), affects around 33% of individuals with DM and includes diabetic retinopathy (DR), diabetic macular edema (DME), and other related conditions. Globally, it is estimated that nearly 93 million people have DR, with 17 million having proliferative DR (PDR), 21 million experiencing DME, and 28 million facing vision-threatening DR, representing significant public health burdens. The prevalence rates for these conditions among individuals with DM are approximately 35.4% for DR, 7.2% for PDR, 7.4% for DME, and 11.7% for vision-threatening DR.
DME, characterized by macular thickening and edema resulting from DM-associated retinal microvascular damage, presents a risk of visual impairment when located near the fovea. Raised blood glucose levels contribute to abnormal retinal permeability and ischemia, leading to the leakage of fluid and lipid-rich exudates into the surrounding retina, causing distortions in the normal retinal architecture.
The global prevalence of DME varies depending on geographic region and diabetes type, with substantially higher rates observed in individuals with type 1 diabetes mellitus (T1DM) (14% in worldwide pooled data) compared to those with type 2 diabetes mellitus (T2DM) (6% in worldwide pooled data). Prevalence rates of DME are similar between genders, but ethnicity plays an important role, with higher rates among African Americans and lower rates among Asians. The 10-year incidence of DR in individuals with T1DM is nearly 36%, while the incidence of DME development reaches 11%.
The overall prevalence of DME among individuals over 40 years of age is 3.8%, equivalent to approximately 746,000 individuals, with increased risk associated with higher levels of glycated hemoglobin (A1C) (>7%) and longer disease duration.
Hypoxia in diabetic eye disease stimulates the release of vascular endothelial growth factor (VEGF), causing increased vascular permeability and retinal edema.
Conventional optical coherence tomography (OCT) may not detect abnormalities in retinal microvasculature, leading to poor visual recovery despite successful treatment of macular edema with laser photocoagulation or intravitreal anti-VEGF agents.
Optical coherence tomography angiography (OCTA) is a noninvasive imaging modality that provides depth-resolved images of retinal and choroidal microvasculature, enabling visualization of specific vascular patterns and better understanding of retinal microvascular changes in diabetic retinopathy (DR).
The purpose of this study is to use OCTA to evaluate the changes in retinal vascular area (the superficial capillary plexus (SCP) and deep capillary plexus (DCP) and the foveal avascular zone (FAZ) after intravitreal lucentis in DME and its effect on the visual acuity.
This cohort study was carried out on eligible participants with type 2 diabetes and diagnosed with DME. A sample size of 30 eyes from 30 patients was determined based on power analysis calculations. The methodology involved a comprehensive ophthalmic evaluation of the enrolled patients, including SD-OCT, OCTA, best corrected visual acuity (BCVA), tonometry, slit lamp, and indirect fundus examination at baseline, 1 month, 2 months, and 3 months. Monthly loading injections of lucentis were administered for three months, and OCTA assessment was performed using a 3×3 mm2 scan centered on the fovea.
Summary of our results:
• The current study was carried out on 30 patients with type 2 diabetes who were previously known to be diagnosed with diabetic macular edema. Their mean age was 59.1 years ±8.42. Male gender represented 53% of the studied patients while female gender represented 46%.
• Baseline visual acuity, assessed using the Landolt C chart, was recorded as 0.43±0.22. Notably, significant improvements in visual acuity were observed at each follow-up visit. At the first month, visual acuity increased to 0.51±0.2, followed by further improvement at the second month (0.69±0.26) and third month (0.74±0.22). Statistical analysis using repeated ANOVA demonstrated a significant difference in visual acuity among the different time points (p<0.001*).
• Mean level of FAZ was 0.2±0.15 mm2 before treatment and 0.17±0.09 mm2 after treatment. FAZ had decreased significantly over the course of the treatment (P-value=0.032).
• At baseline, the mean FAZ size within the SCP was recorded as 0.42±0.14. During the early course of treatment with intravitreal lucentis, there was a slight increase in the FAZ size, although the changes were not statistically significant then decrease in size , The FAZ size in the first month was 0.44±0.18, followed by 0.46±0.22 in the second month and 0.49±0.42 in the third month. FAZ SCP (Within 3x3 mm2) had significantly decreased over the course of the treatment (P-value=0.041).
• The pre-treatment and post-treatment FAZ de in the DCP was 0.75±0.33 and 0.7±0.32 respectively. Repeated measurements of FAZ area in the DCP showed improvement with time but with no statistically significant difference (P-value= 0.659).
• The pre-treatment and post-treatment retinal vascular density in the SCP was 38. 2±4.0 and 38.0 ±3.9 respectively (P-value=0.041*).
• BCVA has a significant positive correlation with central macular thickness (CMT) (r = 0.392, p = 0.032*). However, no significant correlations were found between BCVA and age (r = -0.107, p = 0.574), foveal avascular zone (FAV) (r = 0.213, p = 0.258), FAZ SCP (r = 0.246, p = 0.190), FAZ DCP (r = 0.052, p = 0.784), or RVA DCP (r = -0.289, p = 0.121).
• Notably, a significant negative correlation was observed between BCVA and RVA SCP (r = -0.401, p = 0.028*).
• Pretreatment BCVA (r = 0.423, 95% CI = -0.329 to 0.463, p < 0.001*), central macular thickness (CMT) (r = 0.008, 95% CI = 0 to 0.015, p < 0.001*), have significant positive associations with post-treatment BCVA. However, no significant associations were found between post-treatment BCVA and pretreatment foveal avascular zone in the superficial capillary plexus (FAZ SCP) (r = -0.305, 95% CI = -0.892 to 0.282, p = 0.296) or foveal avascular zone in the deep capillary plexus (FAZ DCP) (r = -0.124, 95% CI = -0.387 to 0.139, p = 0.343).
• The baseline RVA in the DCP was recorded as 40.6±6.4%. Throughout the treatment period with intravitreal lucentis, slight variations in the RVA percentage were observed, but these changes were not statistically significant. The RVA percentages at the first month, second month, and third month were 40.7±5.0%,38.9±8.0%, and 37.8±7.1%, respectively.
• Pretreatment retinal vascular area in the superficial capillary plexus (RVA SCP) (r = -0.247, 95% CI = -0.272 to 0.165, p = 0.024*) showed significant negative associations with post-treatment BCVA.