Comparative Examination of the Electrophysiological Tests Indicators of the Visual Analyzer According to the Type of Newly-Diagnosed Diabetes Mellitus
Author: Mermeklieva, Еlena A.1, Grozeva, Greta G.2, Tomova, Maria G. 2, Solakov, Dimitar D.3, Haralanov, Lyubomir H.3, Tankova, Tzvetalina I.2, Damianov, Vladimir P.4
1 Clinic of Ophthalmology, University Hospital “Aleksandrovska”, Sofia, Bulgaria
2 Clinical center of endocrinology and gerontology, Medical University, Sofia, Bulgaria
3 Clinic of Neurology, NHH, Bulgaria, 4 DCC 8, Sofia, Bulgaria
Aim: The aim of the study was to explore objectively the function of the visual analyzer by simultaneously
performed pattern electroretinography (PERG) and visual evoked potentials (PVEPs) in patients with newly diagnosed diabetes mellitus (DM) and to compare the results with the control group and between the two types of
Material and methods: A group of 81 people (162 eyes) were studied. Patients with DM were 34 (68 eyes), 18 patients with type 1 DM and 16 with type 2 DM. The control group consisted of 47 healthy individuals (94 eyes). Two types of objective electrophysiological (EF) methods were performed – PERG and PVEPs. The main variables that were considered in the results analysis were the latency and amplitudes, reflecting the configuration of the wave forms.
Results: The comparative analysis of the components of the two EF studies between patients with newly-diagnosed DM and controls as well as according to the type of DM demonstrated significant differences. In the comparative analysis of components of the two EF studies between patients with newly-diagnosed DM and controls it was found that the two groups statistically differed in P50 amplitude in PERG which was lower in the diabetic group. PVEPs had statistically significant prolonged latencies of all components (except N145) at the central recordings and in 20% of the peripheral recordings in the diabetic group. In the comparative analysis according to the type of DM, significant differences occurred in components N75 and P100 latencies in PVEPs – longer in type 2 diabetes. The values of the components of the EF studies in type 1 DM were pathological compared to the control group but better than those of the type 2 diabetic group. There was no significant difference between the two types of DM in the amplitude of PVEPs, as well as in the amplitudes and latencies of PERG.
Conclusion: EF studies could be used as an objective method for registration of early changes in the visual
analyzer function as a DM complication. Also, to monitor the changes in dynamics as they are non-invasive, harmless, faster, and less expensive than fluorescein angiography (FA), OCT and angio-OCT.
Key words: Pattern electroretinography, visual evoked potentials, Diabetes mellitus