Correlation of Visual Evoked Potentials with Duration of Diabetes in Type 2 Diabetes Mellitus Patients

Introduction Chronic hyperglycemia of diabetes is associated with dysfunction and failure of various organs, especially the eyes, kidneys, neves, heart and blood vessels. Visual evoked potential (VEP) test evaluates how the visual system responds to light. As it tests the function of the visual pathway from the retina to the occipital cortex, VEP is a useful clinical tool in the diagnosis and documentation of visual impairment in many ophthalmological disorders. Analysis of pattern reversal VEPs may provide early diagnosis of diabetic changes and determine prognosis during treatment. The visual evoked potential is suggested to be a sensitive indicator of functional changes in the visual processing pathway. Aims and Objectives The objective of this study was to establish whether duration of DM has an effect on the VEP measurements, P100 wave latency. Material and methods VEP was recorded in 60 type 2 diabetic patients and compared to 60 age and sex matched normal healthy non-diabetic controls. The patients were divided into three groups based on the duration of diabetes. VEP was recorded with a pc based, two channel, RMS EMG EP MK II machine. Comparison between two groups were done using independent Students’ ‘t’ test.. One way ANOVA (Analysis of Variance) and multiple comparisons were done using post hoc Tukey Multiple Comparison Test to compare the variables between the three study groups. To determine correlation between variables, Pearson's correlation coefficient was used. The mean difference was statistically significant at p<0.05 Result P100 wave latency was significantly longer in diabetic patients as compared to normal controls (P<0.001); There was significant reduction in N75-P100 amplitudes in diabetic subjects(p<0.01). Duration of diabetes was found to influence the VEP parameters as statistically significant increase in the mean P100 latency with the duration of the disease.(110.2+6.51 ms in group <3 yrs duration of DM, 113.4 +5.00 ms in 4–6 yrs duration group, 118.2+4.23 ms in 7–10 years duration group) (p< 0.01). On applying, Pearson's correlation coefficient test, significant positive correlation was observed between P100 latency and duration of diabetes. (r = 0.5803; p <0.001). Conclusion It is concluded that diabetes has effect on the visual pathway and changes in VEP response in diabetic patients are correlated with duration of disease. So, VEP can be used for early diagnosis of diabetic changes of the visual pathway.