Abstract
Purpose: :
To determine normative values for pattern-reversal electroretinogram (PERG ) in healthy adult volunteers.
Methods: :
Participants were 30 healthy volunteers (15 males) with ages from 18 to 61 years (mean=30.8 ±8.7 yrs.; median=29.5 yrs). Inclusion criteria were: visual acuity 0.0 logMAR in each eye, absence of visual complaints, normal fundus, no history for ocular or neurological diseases and informed consent. PERG was recorded from each eye in a darkened room at 1 m from a high resolution display monitor. Stimuli were monochromatic checkerboards subtending 60’, 15’ e 7.5’ minutes of visual angle reversing at 1.9 Hz and 100% of contrast. Responses were obtained from disposable fiber electrodes (patent request PI0602186-7, INPI, Brazil). Latency (ms) for N35, P50 and N95 components as well as peak-to-peak amplitudes (µV) for N35-P50 and P50-N95 were determined. For normative values only results from one randomly chosen eye were included. Normal limits were calculated as 97.5% percentiles for latency and 2.5% percentile for amplitudes for each stimulus size.
Results: :
Normal limits for N35, P50 and N95 latencies for 60’, 15’ and 7.5’ stimuli were respectively: N35 - 40.1, 39.9 and 41.3 ms; P50 - 60.5; 64.4 and 65.6 ms and N95 - 103.4; 104.6 and 104.6 ms. For amplitude the normative values for N35-P50 and P50-N95 for 60’, 15’ and 7.5’ were respectively: N35-P50 - 1.7; 1.6 and 0.9 µV; P50-N95 - 3.8; 2.8 and 1.5 µV. Mean and respective standard deviations for latency and amplitude are shown in the Table below.
No gender differences were found either for latency or for amplitude in the 3 stimulus sizes.
Conclusions: :
PERG normative values were determined for both amplitude and latency. These normative limits are essential for precise diagnosis of ganglion cell and macular dysfunctions. The current results are comparable to previous reports in the literature.
Keywords: electroretinography: clinical • electrophysiology: clinical • ganglion cells