Purpose To evaluate the effect of baseline test selection on progression detection of circumpapillary retinal nerve fibre layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) in glaucomatous eyes by optical coherence tomography (OCT)-guided progression analysis (GPA).

Methods A total of 53 eyes with either RNFL or GCIPL progression determined using OCT-GPA were included. Three different baseline conditions were created by dividing eight serial OCT tests from each eye into three sets. Specifically, these sets presented baseline tests at exams 1–2 (1st set), 2–3 (2nd set) and 3–4 (3rd set), respectively. Agreement on progression detection was defined as the presence of ‘Possible Loss’ or ‘Likely Loss’ in the 2nd or 3rd sets at the same location in the 1st set.

Results The proportion of eyes with agreement on progression detection was 47.1%, 20.0% and 31.0% for RNFL ‘thickness map progression’, ‘thickness profiles progression’ and ‘average thickness progression’, respectively. In GCIPL ‘thickness map progression’ and ‘average thickness progression’, 53.8% and 62.8% of eyes showed agreement, respectively. Eyes with disagreement showed a greater change in thickness (slope of change in the 3rd set−1st set) compared to the eyes with agreement (p<0.05), with the exception of RNFL ‘thickness profiles progression’ (p=0.064).

Conclusion Glaucoma progression detection by OCT-GPA was affected by baseline test selection, especially in eyes with a greater reduction in progression. GCIPL thickness was less influenced by baseline test selection compared to RNFL thickness.