The aim of the study was to compare the reproducibility of the optical coherence tomography retinal nerve fibre layer (OCT RNFL) thickness map between glaucomatous and fellow normal eyes of unilateral glaucoma patients. The authors carried out a prospective case controlled study enrolling 107 newly diagnosed unilateral glaucoma patients. Only those that had stable controlled IOP were included. The glaucomatous eye had typical optic nerve damage with typical visual field defect. OCT images were taken on the Cirrus HD-OCT. Seventy-nine Asian subjects were eligible of the 107 to be included. The authors concluded that the test-retest variability’s and tolerance limits of the Cirrus HD-OCT RNFL thickness map of the glaucomatous eyes were lower than the normal eyes. The authors suggest that adjusting the tolerance limits on the basis of the baseline RNFL thickness values might help improve the ability to recognise progression. Further prospective studies are needed as this study was carried out on all Asian ethnic group using scans of high image quality exclusively and authors advise that care should be taken when analysing poorer quality scans.