Abstract
Purpose: :
To evaluate the interrelation of mf–ERG, especially of the second order kernel response in the superior, inferior, nasal and temporal region and the threshold of static visual field in patients with optic nerve lesions.
Methods: :
Twenty eyes of twenty normal volunteers and eight eyes of eight patients with optic nerve lesions were tested. The mf–ERG was recorded with the VERIS Science system 5.0.4. The visual stimulus was made up of 37 hexagons in an approximately 40–degree visual field, pseudo–randomly alternated between black (5cd/m2) and white (200cd/m2) on the CRT monitor. The Burian–Allen ERG Electrodes, Adult–bipolar or Pediatric–bipolar, were used for this testing. Recording time was approximately 8min. with dilated pupils having the best–corrected visual acuity. Band pass filter was set from 10 to 100 Hz. Each trace of the 1st and 2nd order kernel response was analyzed in the central seven hexagons, superior, inferior, nasal and temporal region in a 5–degree radius area. To prevent the influence from the inter–subject variation, each amplitude of P1, N2 and P1–N2 of the second order kernel response was divided by the amplitude of N1–P1 of the first order kernel response (P1/1st, N2/1st and P1–N2/1st). The ratio of the response in each region as superior/inferior or nasal/temporal region was also analyzed.
The static visual field was examined by the central 10–2 threshold test of the Humphrey Field Analyzer. The mean deviation (MD) was applied for the analysis of the correlation between each measurement value of the 2nd kernel response.
Results: :
The ratio of P1–N2 of the 2nd kernel response in the superior and inferior region had no significant difference between the patients with optic nerve lesion and normals. The ratio of P1–N2 of the 2nd kernel response in the nasal and temporal region increased in the patients with optic nerve lesion compared to normals (P= 0.0000545). There was correlation between P1–N2/1st in the center region and MD (R=–0.7619, P=0.0438). There was no correlation between the ratio of P1–N2 of the nasal/temporal region and MD.
Conclusions: :
Although there was no correlation between the nasal/temporal ratio of P1–N2 of the second kernel response and MD, the nasal/temporal ratios in the all patients with optic nerve lesions fell outside of the normal range. The ratio of the nasal/temporal region was sensitive to optic nerve lesion.
Keywords: neuro-ophthalmology: optic nerve • electroretinography: clinical • visual fields