Pattern Visual Evoked Potential in Adult Amblyopia Referred to the Central Draft Physical Examination Office of the Military Manpower Administration in South Korea.

Purpose: To evaluate visual evoked potential (VEP) as a diagnostic tool for amblyopia and determine threshold values for conscription grading.

Methods: Between February 2023 and April 2024, 148 men (mean age, 21.68 ± 3.22 years; range, 19-25 years) who underwent conscription examination were retrospectively reviewed and categorized into three groups based on their best-corrected visual acuity (BCVA) of the eye with poorer vision using Snellen chart criteria: mild amblyopia (active duty [group A], BCVA >0.6), Moderate amblyopia (supplementary service [group B], 0.1< BCVA ≤0.6), or severe amblyopia (wartime labor [group C], BCVA ≤0.1). The primary outcome measures were VEP parameters selected to objectively classify amblyopia severity (groups A-C) and determine diagnostic thresholds relevant to military service grading. These included P100 amplitude, P100 latency, interocular amplitude difference ratio (IADR), interocular latency difference ratio (ILDR), as well as the ratios of P100 amplitude and latency between the amblyopic and nonamblyopic eyes.

Results: With increasing amblyopia severity, P100 amplitude decreased (group A, 9.86 ± 2.87 μV; group B, 6.52 ± 1.96 μV; group C, 4.56 ± 2.00 μV), while P100 latency increased (group A, 114.79 ± 4.81 msec; group B, 117.67 ± 6.20 msec; group C, 122.35 ± 11.84 msec). Significant differences in P100 amplitude were observed among all three groups (p < 0.001). P100 latency showed a statistically significant difference between group C and the other groups (p < 0.001). Receiver operating characteristic analysis revealed that P100 amplitude (5.5 μV), IADR (0.4), and P100 amplitude ratio (0.6) effectively distinguished group A from groups B and C (area under the curve >0.8), while ILDR (0.08) differentiated group B from group C (area under the curve, 0.751).

Conclusions: VEP measures, including P100 amplitude, IADR, and ILDR, show potential for amblyopia diagnosis and differentiation of conscription grades.