Pattern electroretinogram association with spectral domain-OCT structural measurements in glaucoma

Purpose

To describe the association between pattern electroretinogram (PERG) amplitude and spectral domain-optical coherence tomography (SD-OCT) macular thickness, retinal nerve fibre layer (RNFL) thickness and optic disc topography measurements.

Subjects and methods

Both eyes (n=132) of 66 glaucoma patients (mean age=67.9 years) enroled in the University of California, San Diego, CA, USA, Diagnostic Innovations in Glaucoma Study (DIGS) were included. Eyes were tested with PERG (Glaid PERGLA, Lace Elettronica, Pisa, Italy), RTVue SD-OCT (Optovue Inc., Fremont, CA, USA) GCC, and NHM4 protocols on the same day. Of the 66 enroled patients, 43 had glaucoma defined by repeated abnormal standard automated perimetry (SAP) results in at least one eye and 23 were glaucoma suspects defined by a glaucomatous-appearing optic disc by physicians'' examination in at least one eye and normal SAP results in both eyes. Associations (R ²) were determined between PERG amplitude (μV) and SD-OCT macular ganglion cell complex (GCC) thickness (μm), macular thickness (μm), macular outer retinal thickness (macular thickness minus GCC thickness) (μm), RNFL thickness (μm), neuroretinal rim area (mm²), and rim volume (mm³).

Results

PERG amplitude was significantly associated with GCC thickness (R ²=0.179, P<0.001), RNFL thickness (R ²=0.174, P<0.001), and macular thickness (R ²=0.095, P<0.001). R ² associations with other parameters were not significant (all P>0.624). Significant associations remained for GCC and average RNFL thickness when age and intraocular pressure at the time of testing were included in multivariate models (both P≤0.030).

Conclusions

PERG amplitude is significantly (but weakly) associated with macular GCC thickness, RNFL thickness, and macular thickness. The lack of association between PERG amplitude and macular outer retinal thickness supports previous results, possibly suggesting that that the PERG is driven primarily by retinal ganglion cell (inner retinal) responses.