Abstract
Purpose::
To examine the test-retest reproducibility of steady-state pattern electroretinogram (PERG) in a cross-sectional population.
Methods::
Normal, glaucoma suspect, and glaucomatous eyes underwent complete ocular examination, standard automated perimetry, and PERG examination. Glaucoma was defined as cup/disc asymmetry between fellow eyes of greater than 0.2, rim thinning, notching, excavation, or RNFL defect associated with a reproducible SAP abnormality, and was staged according to the SAP mean deviation (MD) using the following criteria: early (MD > -6DB), moderate (MD -6 to -12dB) and advanced (MD < -12 dB). One randomly selected eye underwent PERG testing three times on a single day by the same operator. Outcome measures included PERG amplitude and phase. PERG measures represented an average of 600 artifact-free signal registrations. Coefficients of repeatability (CoR), coefficients of variability (CoV), and intraclass correlation coefficients (ICC) were calculated for each subject.
Results::
Seventy two eyes of 72 patients (33 normals, 21 suspects, 18 glaucoma) were enrolled (mean age 58.5±15.1). All eyes with glaucoma had associated SAP abnormalities (average MD = -6.4±5.4). The mean PERG amplitude (microvolts) in normals (0.90±0.32) was significantly (p<0.001) higher than suspects (0.57±0.23) and glaucomatous eyes (0.47±0.18). Mean PERG phase (pi-radian) were similar (p=0.6) amongst the groups (1.8±0.15 normal, 1.7±0.16 suspects, 1.8±0.16 glaucoma). In normal, suspect, and glaucomatous eyes respectively, the CoR of PERG amplitude was 0.1±0.2, 0.1±0.1, and 0.1±0.1; CoV in percentage was 11.3±8.8, 11.5±10.1, and 15.3±12.0, and ICC was 0.95, 0.97, and 0.96. The ICC of intra-session reproducibility for PERG amplitude was 0.96, 0.98, and 0.94 in patients with early, moderate, and advanced glaucoma respectively.
Conclusions::
PERG provides a high level of reproducibility in normals, glaucoma suspects, and glaucomatous eyes and is unaffected by the severity of glaucomatous damage.
Keywords: electrophysiology: clinical