Test–Retest Variability for the Pattern Electroretinogram (PERG) Optimized for Glaucoma Screening (PERGLA) in Glaucoma Suspects and POAG Patients

Abstract

Abstract: : Purpose: To evaluate the test–retest variability for the pattern electroretinogram (PERG) optimized for glaucoma screening (PERGLA) in glaucoma suspects and POAG patients. Methods: 26 glaucoma suspects eyes (13 patients) and 96 eyes (48 patients) affected by POAG under controlled medical therapy with IOP≤18 mmHg measured with the Goldmann tonometer underwent a complete ophthalmic examination and visual field testing with the Humphrey SITA 30–2 at the time of the recruitment. POAG patients were then classified on the base of their MD and CPSD values according to the Brusini’s Glaucoma Staging System (GSS). The PERGLA was performed at day 0 and at day 30 by the same operator. IOP measurements were also taken at day 0 and at day 30 and the IOP difference in the same eye between the two sessions was never greater than 2 mmHg. The CV (SD / Mean x 100) and SD of Amplitude and Phase between two responses recorded in the two sessions were measured. The Pearson’s r and r² correlation coefficients between measurements of Amplitude and Phase recorded at day 0 and at day 30 were also evaluated. Results: The test–retest CVs for the parameters measured were average lower than 9.3%. The Pearson’s r was 0.76 for the Amplitude (p<0.00001) and 0,82 for the Phase (p<0.00001), the r² was 0.57 for the Amplitude (p<0.00001) and 0,67 for the Phase (p<0.00001); therefore a good correlation was found between the measurements taken at the two different sessions. Conclusions: Previous studies reported lower test–retest CVs in a population of normal subjects. Nevertheless in this study the PERGLA appeared to be a reliable and quite reproducible technique in glaucoma suspects and POAG patients thus suggesting its potential use for detecting progression of glaucomatous optic neuropathy, determine the efficacy of neuroprotective agents or monitoring the effects of medical or surgical treatments to lower the IOP.

Keywords: electroretinography: clinical