Abstract
Purpose::
To investigate the association between retinal ganglion cell (RGC) function, retinal nerve fiber layer (RNFL) thickness, and optic nerve head topography.
Methods::
Normal volunteers, glaucoma suspects, and glaucomatous eyes underwent complete eye examination, standard automated perimetry, scanning laser polarimetry (SLP), optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy (CSLO). Retinal ganglion cell function was assessed using steady-state pattern electroretinogram (PERG). An average of three readings was used for the analysis. Each measure of amplitude and phase was an average of 600 artifact-free signal registrations. All participants had visual acuity of 20/30 or better; one eye was randomly enrolled. PERG amplitude (microvolt) was converted to a logarithmic scale (dB) for comparison with visual field mean deviation (MD) and pattern standard deviation (PSD). Multivariate analysis of variance and Pearson correlation coefficients were calculated.
Results::
Eighteen age-matched glaucoma patients (mean age 67.8±8.2 years, average MD -6.4±5.4), 21 glaucoma suspects (mean age 63.0±11.2 years, average MD 0.2±1.1) and 18 normal volunteers (mean age 62.9±10.1 years, MD 0.3±0.7) were enrolled. PERG amplitude was significantly (p=0.006) higher in normals (0.71±0.25) compared with glaucomatous eyes (0.47±0.18), but not glaucoma suspects (0.57±0.23, p=0.15). PERG amplitude (mv) and phase (pi radian) had an inverse correlation with age across the entire cohort (r= -0.34, p=0.009; r= -0.30, p= 0.02 respectively). PERG amplitude (dB) was significantly associated with MD (r= 0.39, p=0.003) and PSD (r= -0.31, p= 0.02). PERG amplitude was correlated with OCT average and inferior RNFL thickness (r= 0.31, p= 0.02), SLP-ECC average TSNIT (r= 0.28, p= 0.03) and CSLO rim volume (r= 0.29, p= 0.03) in the study population (n=57).
Conclusions::
RGC function as measured using PERG is reduced in glaucoma compared to normals, inversely correlated with age, and is directly correlated with visual field MD, RNFL thickness and neuroretinal rim volume.
Keywords: ganglion cells • nerve fiber layer • optic nerve