[The influence of the idiopathic macular hole (IMH) surgery with the ILM peeling and gas tamponade on the electrical function of the retina].

Many contemporary clinical papers establish positive influence of the pars plana vitrectomy (PPV) with the ILM (internal limiting membrane) peeling and gas tamponade in macular hole to the macular morphology. They prove diminishing or disappearing of the central scotoma and metamorphopsia and especially also improvement of the BCVA for far and near. The evaluation of the objective functional condition of the retina is still a discussed question. This paper concerns with the comparison of the electric functions of the retina before and after the IMH surgery with the ILM peeling and the gas tamponade. In the group 19 patients (8 men, 11 women), or 19 eyes with IMH were included. The average age was 69 +/- 6 years. The group consisted of patients with transparent optical media. In none of these patients was found other macular pathology than IMH. Nobody underwent other retinal surgery. The patients were examined 1 day before and 1 and 3 months after the surgery. During each control, the following examinations were performed: the Amsler grid examination, the best corrected visual acuity (BCVA) for far (EDRTS chart) and near (Jaeger optotypes), intraocular pressure measurement (non contact tonometer NIDEK NT-2000), examination of the anterior segment on the slit lamp, examination of the posterior segment biomicroscopically and by means of indirect ophthalmoscopy, examination of the photopic, pattern, and multifocal ERG (Retiscan, according to the ISCEV methodology), and OCT examination (Stratus OCT). If necessary, the ultrasound examination (Ultrascan Alcon) was performed as well. For the statistical evaluation of the ERG component values among the data files before the surgery (data file 1), 1 month after the surgery (data file 2), and 3 months after the surgery (data file 3), the non-parametric Wilcoxon pair test was used. In the photopic ERG, there was statistically significant prolongation of the latency b in data file 2 and 3 comparing to the data file 1 (p < 0.05). Comparing latency b of data file 1 to data file 2, there was found no statistical significance. Comparing other parameters of photopic ERG found no statistically significant difference among data files 1,2, and 3. In the multifocal ERG, there was found statistically significant elevation of the P1 amplitude according to the response density of given unit and the P1 amplitude in the central ring in data file 3 comparing to the data file 1 (p < 0.05). Comparison of other parameters was not statistically significant. In the paracentral ring, there was found statistically significant extension of the N1 and P1 latency in data file 3 comparing to the data file 1 (p < 0.05). Comparison of other parameters in the paracentral ring was not statistically significant. Statistically significant improvement of the retinal electric function in the central 4 degrees 3 months after the surgery, confirms the positive functional effect of the surgery to the fovea. In the fovea, the increase of the number of functional nerve cells of the outer layers of the retina occurs. On the other hand, in the parafoveolar region, as well as in the whole retina, 3 months after the surgery, statistically significant decrease of the function of the retina, meaning the time prolongation of the conduction in the outer layers of the retina, occurs. According also to our results, the peeling of the ILM in the IMH surgery remains, despite its unquestionable contribution, still a controversial technique. During the short, three months lasting, follow-up period, the functional improvement in the fovea occurred, but the functional decrease in the parafoveolar region which correlates in the large extent with area of the ILM peeling was found. The discussion about the ILM peeling indication in the earlier stages is adequate. We will further follow-up the development of the retinal electric function after the IMH surgery with ILM peeling and gas tamponade.