Comparison of baseline clinical characteristics and patterns of visual field defects between high-tension and normal-tension glaucoma

Aims To compare the baseline clinical characteristics and patterns of visual field defects between high-tension glaucoma (HTG) and normal-tension glaucoma (NTG) in the Laser in Glaucoma and Ocular Hypertension (LiGHT) China subjects. Methods All patients (n=622) were recruited at Zhongshan Ophthalmic Center from 2015 to 2019. 1105 open-angle glaucoma eyes of 622 patients were classified as NTG (n=559) and HTG eyes (n=546) according to the baseline intraocular pressure (IOP) of 21 mm Hg. The mean deviation (MD), regional MD of the Glaucoma Hemifield Test regions and regional difference values were calculated. Daytime phasing IOP was recorded at 8:00, 10:00, 11:30, 14:30 and 17:00 hour. Multiple regression analyses were conducted for each regional difference. Results Patients with NTG were older, more likely to be female, hypertensive and suffer ischaemic heart disease than patients with HTG (p<0.05 for all comparisons). HTG showed higher mean daytime phasing IOP and higher daytime fluctuations than NTG (p<0.001 for all comparisons). HTG and NTG showed similar MD overall (p=0.665). NTG showed significantly greater hemifield asymmetry than HTG. The two arcuate regional differences in NTG were significantly associated with daytime IOP fluctuations (p<0.01 in both regions). Conclusions In the LiGHT China trial, NTG and HTG showed similar visual field defects severity at enrolment. However, NTG showed more severe hemifield asymmetry compared with HTG, and higher short-time IOP fluctuations might exacerbate this asymmetry in NTG.