Purpose:
To evaluate the correlations between retinal nerve fiber layer (RNFL) thickness, visual field (VF) findings, multifocal photopic negative response (mfPhNR), multifocal electroretinography (mfERG) and pattern electroretinography (PERG) in patients with normal tension glaucoma (NTG).
Methods:
Twenty-five eyes of 25 patients with NTG were recruited for optical coherence tomography (OCT), VF, mfPhNR, mfERG and PERG assessments. The mean RNFL thickness around the optic nerve head was measured using the Stratus OCT. VF mean deviation (MD) and pattern standard deviation (PSD) values were obtained from 24-2 Humphrey perimetry. mfPhNR was recorded using a 7-hexagon stimulus with a m-sequence of 29 and insertion of 29 dark frames between the multifocal flashes. mfERG was recorded using a 61-hexagon stimulus and responses were grouped into five concentric rings and 7 areas for analysis. Correlation analyses were performed between the OCT, VF, mfPhNR, mfERG and PERG findings. Bonferroni corrections were performed with corrections for multiple testing.
Results:
There were good correlations between RNFL thickness and VF MD (r=0.79, P<0.001) and PSD (r=-0.71, P<0.001). Significant positive correlations were observed between the RNFL thickness and the amplitudes of the mfPhNR amplitudes from the four peripheral hexagons (r=0.51 to 0.53, P<0.05). The local mfPhNR amplitudes of the superior visual field also correlated with the local VF sensitivity values (r=0.58 to 0.62, P<0.05) No significant correlation was found between the RNFL and VF findings with the mfERG amplitudes and implicit times and the PERG P50 and N95 amplitudes and N95/P50 ratios (P>0.05).
Conclusions:
The findings demonstrated that mfPhNR responses appeared to be specific to retinal ganglion cells and mfPhNR from the peripheral macula might be a useful tool for the topographic assessment of glaucomatous visual field loss.
Keywords: electroretinography: clinical • electrophysiology: clinical • nerve fiber layer