Evaluation of Cortical and Retinal Activity in patients with Type 2 Diabetes Mellitus (DM) and the role of Vascular Endothelial Growth Factor (VEGF) in the pathogenesis of Diabetic Retinopathy (DR)

Vidhya, A (2017) Evaluation of Cortical and Retinal Activity in patients with Type 2 Diabetes Mellitus (DM) and the role of Vascular Endothelial Growth Factor (VEGF) in the pathogenesis of Diabetic Retinopathy (DR). Masters thesis, Madras Medical College, Chennai.


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BACKGROUND: DM with its morbidity and mortality is considered the biggest health challenge of the present century. DR one of the microvascular complications of DM is the most devastating of its ocular complications. The pathogenesis of DR is related to the background of chronic hyperglycemia, release of glycation end products which in turn cause release of reactive oxygen species. VEGF mediated mechanisms cause break in the blood-retinal barrier and neovascularisation, important events in DR. Visual evoked potentials (VEP) are complex neurosensory impulses originating along the optical tract and can be recorded from the scalp, and predate clinical DR findings. AIM AND OBJECTIVES: To compare the VEP responses, and VEGF levels between non-diabetic controls having no known eye disease, with 40 age and sex matched diabetic patients with and without retinopathy. MATERIALS AND METHODS: This prospective case control study was approved by the Institute’s Ethical Committee, and performed on patients who presented to the Department of Diabetology, Madras Medical College Hospital from July 2015 to July 2016. All patients underwent a thorough clinical and ophthalmic evaluation. The control group (Group1) included 20 non diabetic subjects with no known eye disease. These were compared with 40 age and sex matched patients without (Group 2) and with DR (Group 3). VEP studies were performed on all patients using the Physiopac VEP machine at the Research Laboratory of the Institute of Physiology and Experimental Medicine, Madras Medical College, Chennai. VEP N75, P100 and N145 waveforms were recorded for all patients for both eyes with mean and standard deviations recorded overall. The results were compared for any significance using One way ANOVA with SPSS21 software. Fasting serum VEGF levels were calculated for all the patients using Ray Biotech VEGF A Elisa kit, and the results were compared between controls and diabetics with and without retinopathy using ANOVA and unpaired t test for any significant difference. RESULTS: There was a significant prolongation in the N75 and P 100 latency in group 2 and 3 patients when compared to the control group (Group 1). There was no significant prolongation of N 145 latency in group 2 and 3 subjects when compared to group 1 subjects. When P100 wave forms were compared, not only were they prolonged in diabetics but there was a significant increase in the latency in diabetics with retinopathy (Group 3) as compared to those without retinopathy (Group 2). Also there was a significant increase in the P100 latency with duration of disease. VEGF levels showed some difference between diabetics in groups 2 and 3 as compared to the control group, however these were not statistically significant. CONCLUSION: VEP studies can detect retinopathy even before they are clinically visible. This makes them an important tool in the management of DR. Our study confirms the use of P100 wave forms which show significant increase in diabetics with retinopathy, as compared to those without DR and from non-diabetics. Also they show increase with duration of disease. Serum VEGF levels, however may not have a role in management of DR.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Diabetes Mellitus, Diabetic Retinopathy (DR), Visual Evoked Potential (VEP), Vascular Endothelial Growth Factor (VEGF), blood-retinal barrier.
Subjects: MEDICAL > Physiology
Depositing User: Subramani R
Date Deposited: 18 Jul 2020 17:55
Last Modified: 19 Jul 2020 07:46
URI: http://repository-tnmgrmu.ac.in/id/eprint/12552

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