AbstractThis prospective, observer-masked, randomized clinical trial was conducted between December 2018 and June 2021 at Eye Hospital, China Academy of Chinese Medical Sciences. A total of 45 glaucoma patients from Beijing, China, were enrolled in this clinical trial to compare the short-term efficacy of primary single-selective laser trabeculoplasty (SLT) to 0.005% latanoprost eye drops for the treatment of 24-h intraocular pressure (IOP) in patients with newly diagnosed primary open angle glaucoma (POAG) and ocular hypertension (OHT). Both SLT and latanoprost significantly decreased mean 24-h IOP and peak IOP, although the latanoprost group effect was more potent when compared to the SLT group (both Ps < 0.05). Compared with the SLT group, the latanoprost group had a significant and stable decrease in IOP after treatment. The latanoprost group had a more pronounced reduction in IOP at weeks 4 and 12 (P < 0.05) but had no difference at week 1 (P = 0.097). As a first-line treatment, both SLT and latanoprost eye drops are effective in newly diagnosed POAG and OHT patients. However, the latanoprost eye drops may be better in decreasing mean and peak 24-h IOP and thus controlling 24-h IOP fluctuation compared to SLT.