الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Diabetic macular edema (DME) is the leading cause of blindness in the diabetic population, and its prevalence is variable. The Diabetes Control and Complications Trial (DCCT) reported that 27% of type 1 diabetic patients developed macular edema within 9 years of diabetes onset. Diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) are the major sight-threatening endpoints of diabetes.
Diabetic retinopathy is asymptomatic in the early stages and there is a need for regular eye screening for patients with diabetes to enable timely diagnosis and subsequent management of the condition.
Diabetic retinopathy is most commonly diagnosed through direct and indirect ophthalmoscopes, but there are many other imaging modalities that can be used to screen, evaluate, diagnose, and treat the various presentations of this disease. The most widely used imaging modality for diabetic retinopathies is currently Fluorescein Angiography (FA). Conventional FA uses retinal photography, which is capable of viewing from 30° through 60° in a single exposure, meaning that the peripheral retina is not visible. Ultrawide field FA has been developed to provide better imaging of the peripheral retina.
This study was conducted on 50 eyes of diabetic patients diagnosed clinically, by fluorescein angiography and optical coherence tomography as having diabetic retinopathy with macular oedema.
The age of the studied patients varied between 37 years and 75 years, with a mean age of 52.38 ± 11.52 years. Females represented 60.0%. The BCVA ranged from 0.18 – 1.30 LogMar.
In our study we used UWFA to evaluate retinal ischaemia and identify its relationship with DME. Images taken after intravenous injections of fluorescein were compressed into high quality jpeg files then were transferred to Adobe software and were analyzed for retinal non-perfusion. Retinal ischemia was defined as angiographically visually significant hypofluorescence of an area of at least one disc diameter (representing retinal non-perfusion or capillary dropout).
Capillary non-perfusion was calculated by a quantitative methodology, each eye was evaluated for presence or absence of retinal ischemia using UWFA images. So we measure total area of retina in pixels ranged from 454544–1878184 pixels with mean range 1694013±416663 pixels and peripheral capillary non- perfusion among studied group; it ranges from 15.53 – 1460.13 pixels with a mean of 37394 ±42619 pixels. Creating a percentage of ischemia over the total area of the retina called ischemic index.
Ischemic index among studied group ranged from 0.85 – 79.16 % with mean 29.0 ± 16.52. The Central foveal thickness varied from 110.0 – 910.0 microns among studied group with a mean thickness of 349.40 ± 138.06 microns. Using the Pearson correlation coefficient we found that there was statistically significant correlation between peripheral ischemia index and central foveal thickness P≤ 0.004.
While comparing ischemic index according to diabetic retinopathy severity, mild cases had ischemic index of 4.8%, moderate 24.1% and severe cases had ischemic index of 30% and Significant statistical relation between severity and ISI P≤0.004..
Regarding the type of macular edema and the ischemic index, we found no significant statistical relation between the type of macular edema either on FA or OCT. However, cystoid edema with NRD was associated with higher ischemic index with a mean 38.90 ± 19.39
There is a significant correlation between DME and PRI. UWFA is a useful tool for detecting PRI which may have direct implications in the diagnosis, follow-up and treatment.
UWFA can help to directly guide the management of DR while sparing healthy retinal tissue and minimizing PRP’s side effects by directing PRP to the ischemia-prone areas rather than the entire retina.
The consistency between Heidelberg WFA and Optos UWFA in evaluating the severity of peripheral ischemia can be compared in studies.