Abstract
Purpose: :
To determine the recording condition of mfPhNR and the clinical application for patients with optic nerve lesions and glaucoma.
Methods: :
Ten eyes of ten volunteers with normal vision and six eyes of three patients with optic nerve lesions or normal tension glaucoma (NTG) were tested.The mfPhNR 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 alternating between black (5cd/m2) and white (200cd/m2) on the CRT monitor. Burian-Allen ERG Electrodes, Adult-bipolar or Pediatric-bipolar, were used for this testing. The recording time was approximately 8 min. with dilated pupils having the best-corrected visual acuity. The band pass filter of the amplifier was set from 0.1 to 300 Hz or from 0.1 to 100 Hz. The amplification and stimulus frequency were set to 10000 and 9.41 Hz (8 frames) respectively.Each trace of the mfPhNR and b-wave was analyzed in the all traces, the all superior and inferior region, in the central hexagons, superior and inferior regions in a 5, 10 and 15-degree radius area.The static visual field was examined with a central 30-2 and 10-2 threshold test using a Humphrey Field Analyzer. The mean deviation (MD) was applied for the analysis of the correlation with the amplitude of mfPhNR.
Results: :
Though the base line of recording was unstable with 0.1 Hz high pass filter, it became stable with 1 Hz by using a digital filter. Even though high frequency noise was obvious with 300 Hz low pass filter, it became reduced keeping the original wave form with 100 Hz. The amplitude of b-wave was normal in patients except the affected eye with optic nerve lesion in central 2.5-degree radius area. The amplitude of mfPhNR in the eye with optic nerve lesion decreased in not only visual field defect area but also normal visual field area. In unaffected eye of patient with optic nerve lesion, the amplitude of mfPhNR was within normal range. In more affected eyes and less affected eyes with NTG, the amplitude of mfPhNR decreased beyond in visual field defect area even in normal visual field area. There is no correlation of the amplitude of mfPhNR with MD or antilog MD of the static visual field.
Conclusions: :
It was appropriate for recording mfPhNR that the band pass filter of the amplifier was set from 1 to 100 Hz and the amplification x10000. The amplitude of mfPhNR decreased beyond in visual field defect area in patients, even in less affected eyes with NTG as same as in more affected eyes with NTG.
Keywords: optic nerve • electroretinography: clinical • visual fields