Abstract
Purpose:
To investigate the ability of transient and steady-state pattern electroretinogram (PERG) to detect amplitude response reduction in pre-perimetric and hemifield loss glaucoma patients. To verify the correlation between PERG and fourier-domain optical coherence tomography (FD-OCT) macular thickness measurements.
Methods:
Fourteen eyes from 9 patients with optic nerve glaucomatous damage (group 1) and 23 eyes from 20 healthy subjects (group 2) were submitted to ophthalmic examination, including standard automated perimetry (SAP - Humphrey 24-2 SITA Standard test) and FD-OCT (3DOCT-1000; Topcon, Inc). Transient and steady state PERG were recorded according to the ISCEV with the RETiscan System (Roland Consult, Wiesbaden, Germany, 2006). The stimulus was binocularly generated with black-and-white checks (measuring 0.24 minutes of arc) with a mean luminance of 80 cd/m2 and a contrast of 97%. Reversal rate was either 3 Hz (transient response) or 10 Hz (steady state response). Amplitudes and peak times for P50 and N95 were measured. OCT-measured full-thickness macular measurements were registered according to an overlaid OCT generated checkboard with 36 checks. Macular thickness measurements were averaged globally and for two half (superior or inferior) of that area. Data from the two groups were compared. Correlation between PERG and FD-OCT was investigated.
Results:
Transient PERG P50 and N95 amplitude measurements (mean ± SD) were 0.82 ± 0.46 and 1.33 ± 0.71 in group 1 and 1.43 ± 0.79 and 2.42 ± 1.39 in group 2 (p=0.004 and 0.004, respectively). Steady-state P1 amplitude was 1.23 ± 0.5 (group 1) and 2.50 ± 1.32 (group 2, p<0.001). Average, superior half and inferior half macular thickness measurements were 242.8 ± 20.5, 250.7 ± 27.4 and 234.8 ± 22.5 for group 1 and 258.2 ± 16.0, 258.3 ± 11.1 and 258.1 ± 26.2 for group 2 (p= 0.014; 0.159 and 0.012, respectively). No significant correlation was found between PERG responses and OCT measurements.
Conclusions:
Although PERG amplitudes (P1, P50 and N95) and OCT measurements (average and inferior hemifield) were significant lower in the glaucoma group compared to controls, no significant correlation was observed between such measurements. Our study suggests that PERG and OCT quantify neural loss differently, but both technologies are useful in detecting abnormalities in patients with glaucoma.
Keywords: 507 electrophysiology: clinical •
613 neuro-ophthalmology: optic nerve •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)