The functional state of the visual analyzer according to electrophysiological indicators in non-arteritic ischemic optic neuropathy

Abstract

Non-arteritic ischemic optic neuropathy ( NAION) is the second leading cause of irreversible vision loss after glaucoma in individuals. Was to assess changes in electrophysiological parameters of the visual sys- tem in patients with NAION using pattern visual evoked potentials (P- VEP) and pattern electroretinography (P- ERG). 21 Patients (31 eyes) with NAION were examined. The mean age was 47.5 ± 11.6 years (range: 37–66 years). All patients underwent stand- ard ophthalmic examination. Based on the presence of a central scoto- ma, patients were divided into two groups: group 1 (8 patients—8 eyes) with central scotoma due to axial bundle damage, and group 2 (3 pa- tients (3 patients (3 eyes) were with unilateral N AION and 10 patients (20 eyes)—with bilateral NAION) without central scotoma. Electrophysiologi- cal studies were conducted by the RetiScan system (Roland Consult, Ger- many) in accordance with ISCEV standards. P-VEPs were recorded using 1° and 15′ checkerboard patterns and P-E RG by 48′ checkerboard pattern. Statistical analysis was performed using I BM SPSS Statistics with signifi- cance p < 0.05. Visual acuity in the group 1 was 0.15± 0.1, 2-d group—0.62± 0.3. No sig- nificant differences were found in P- VEP latencies (N75 and P100) between the groups. The P- VEP P100 amplitude to the 1° stimulus was 9.0 ± 3.3 µV in group 1 and 13.1 ± 5.3 µV in group 2 (1.45 times higher, p = 0.04). The P- VEP P100 amplitude to the 15′ stimulus was 8.9 ± 2.7 µV in group 1 and 13.1 ± 5.3 µV in group 2 (1.45 times higher, p = 0.02). The factor of the ax- ial bundle damage was significant for the 15′ VEP amplitude—F = 4.23, p = 0.048. There was a direct correlation r = 0,44 (p < 0.05) between the vis- ual acuity and the 15′ VEP amplitude. The bioelectrical activity of ganglion cells of central retina was assessed using P-E RG. Latency values (N35, P50, N95) did not differ significantly between groups. The N35-P50 amplitude was 3.5 ± 1.3 µV in group 1 and 4.5 ± 1.6 µV in group 2 (1.28 times higher, p = 0.05). The P50-N95 ampli- tude was 4.2 ± 1.4 µV in group 1 and 5.7 ± 2.4 µV in group 2, but was not different (p = 0.09). These results suggest reduced functional activity of ganglion cells in the central retina region. Electrophysiological changes in N AION are heterogeneous and depend on the location of damage. In patients with axial bundle depression, P-V EP amplitudes were reduced by 1.5 times and P- ERG amplitudes by 1.2 times. Latency parameters remained stable.