Abstract
Purpose: :
To describe the association between PERG amplitude and SD-OCT measurements of macular thickness, retinal nerve fiber layer (RNFL) thickness and optic disc topography.
Methods: :
The worst eye (based on standard automated perimetry MD; MD = -2.77 dB, SD = 3.32 dB) of 66 glaucoma patients (mean age = 67.8 years, SD = 12.5 years) enrolled in the UCSD Diagnostic Innovations in Glaucoma Study (DIGS) was tested with PERG (Glaid PERGLA, Lace Elettronica, Rome, Italy) and RTVue SD-OCT (Optovue, Fremont, CA) GCC and NHM4 imaging protocols on the same day. Associations (R2) were determined between PERG amplitude (µV) and SD-OCT macular ganglion cell complex (GCC) thickness (µm), macular thickness (µm), macular outer retinal thickness (i.e., macular thickness minus GCC thickness) (µm), RNFL thickness (µm), neuroretinal rim area (mm2), and neuroretinal rim volume (mm3). Because the PERG response relies on a centrally presented stimulus we hypothesized that PERG measurements would be most strongly associated with macular parameters, in particular GCC thickness because PERG is assumed driven primarily by retinal ganglion cell responses.
Results: :
PERG amplitude was most strongly associated with GCC thickness (R2 = 0.23, p < 0.001) followed by RNFL thickness (R2 = 0.21, p < 0.001) and macular thickness (R2 = 0.11, p = 0.007). All correlations were positive. Associations with other parameters were not significant (all p > 0.180). Significant associations remained for GCC and average RNFL thickness when participant age and IOP at the time of testing were included in multivariate models (p ≤ 0.004).
Conclusions: :
PERG amplitude is significantly (but somewhat weakly) associated with macular ganglion cell complex thickness, RNFL thickness and macular thickness. Similar association of PERG amplitude with both GCC thickness and RNFL thickness might suggest that PERG is measuring more than just a central response. The lack of association between PERG amplitude and macular outer retinal thickness supports previous results suggesting that that the PERG is driven primarily by retinal ganglion cell (inner retinal) responses. The lack of association between centrally measured PERG amplitude and optic disc topography might be due in part to the relatively small contribution of the temporal rim to global rim measurements.
Keywords: electrophysiology: clinical • imaging/image analysis: clinical