Abstract
Purpose: :
To record the photopic negative response of multifocal electroretinograms (mfPhNR) in normal and glaucomatous eyes to evaluate and compare the change of mfPhNR in them.
Methods: :
Eight eyes age-matched normal controls and twenty eyes with glaucoma were evaluated. The mfPhNR was recorded with the VERIS Science SystemTM (EDI, Redwood city, SA) and visual stimulus was set up with five dart-like elements, pseudo-randomly alternating between red (630nm) and blue (450nm) on the CRT monitor. The recording time was two minutes with dilated pupils. The band pass filter of the amplifier was set from 1 to 100 Hz and Burian-Allen electrodes were used for recording. The mfPhNR was analyzed in all five elements. The visual sensitivity was measured by Humphrey Visual Field Analyzer (HFA) and measured scores corresponding to each element were selected for evaluation.
Results: :
The base line of recording was unstable with 0.1 Hz high pass filter, but with 1 Hz. While high frequency noise was obvious with 300 Hz low pass filter, it reduced with 100 Hz. The amplitude of P1 in each element (center, nasal upper, nasal lower, temporal upper, temporal lower; nV/deg2) were 4.6± 3.1, 1.5 ± 1.0, 1.6 ± 1.5, 1.1 ± 0.8, 1.2 ± 0.8 in normal eyes and 4.1 ± 3.0, 1.7 ± 1.4, 2.0 ± 1.3, 1.8 ± 1.4, 2. ± 1.3 in glaucomatous eyes, there was no statistical difference between the two groups. The amplitude of mfPhNR in each element were 3.4 ± 1.2, 1.5± 0.3, 1.4± 0.3, 1.5 ±1.8, 1.3± 0.4 in normal eyes and 0.7± 0.4, 0.6± 0.5, 0.6± 0.4, 0.5± 0.3, 0.7± 0.5 in glaucomatous eyes respectively. There was statistical difference between the them (P< 0.0001). Between the sensitivity (dB, log scale) and the mfPhNR amplitude, a curvilinear relationship was found.
Conclusions: :
We succeeded in recording mfPhNR from normal and glaucomatous eyes using red on blue background stimulus condition. The reduction of the mfPhNR amplitude associated with local decrease in the retinal sensitivity in glaucoma. The mfPhNR can be useful index to detect retinal functional damage in glaucomatous eyes.
Keywords: electroretinography: clinical • electrophysiology: clinical • perimetry