PurposeThe laser in glaucoma and ocular hypertension (LiGHT) trial aims to establish whether initial treatment with selective laser trabeculoplasty (SLT) is superior to initial treatment with topical medication for primary open angle glaucoma (POAG) or ocular hypertension (OHT).DesignLiGHT is a prospective unmasked, multicentre, pragmatic, randomised controlled trial (RCT).Participants718 previously untreated patients with POAG or OHT were recruited at 6 UK centres between 2012 and 2014.MethodsPatients were randomised to initial SLT followed by medical therapy or medical therapy without laser. Participants will be monitored for 3 years, according to routine clinical practice. The primary outcome is EQ-5D-5L. Secondary outcomes are treatment pathway cost and cost-effectiveness, Glaucoma Utility Index (GUI), Glaucoma Symptom Scale, Glaucoma Quality of Life (GQL), pathway effectiveness, visual function, safety and concordance.ResultsA total of 555 patients had POAG and 163 OHT; 518 patients had both eyes eligible. The mean age for patients with POAG was 64 years and for OHT 58 years. 70% of all participants were white. Median IOP for OHT eyes was 26 mm Hg and 23 mm Hg for POAG eyes. Median baseline visual field mean deviation was −0.81 dB for OHT eyes and −2.82 dB for POAG eyes. There was no difference between patients with POAG and patients with OHT on the EQ-5D-5DL; the difference between OHT and POAG on the GUI was −0.02 and 1.23 on the GQL.ConclusionsThe LiGHT trial is the first RCT to compare the two treatment options in a real-world setting. The baseline characteristics of the LiGHT cohort compare well with other landmark glaucoma studies.Trial registration numberISRCTN32038223, Pre-results.