Intraocular pressure reduction with topical medications and progression of normal-tension glaucoma: a 12-year mean follow-up study.

PURPOSE: To investigate whether the amount of intraocular pressure (IOP) reduction with topical medications is associated with the progression of normal-tension glaucoma (NTG) and to identify risk factors for NTG progression.

METHODS: The medical records of 121 eyes of 121 NTG patients, who were treated with topical medications for more than 7 years, were reviewed. NTG progression was defined by either structural (optic disc or retinal nerve fibre layer) or functional (visual field) deterioration. Patients were divided into tertile groups according to the percentage IOP reduction from baseline, and the cumulative probability of NTG progression between upper and lower tertile group was compared using Kaplan-Meier survival analysis. Multivariate analysis with Cox's proportional hazard model was performed to identify the hazard ratio (HR) of clinical factors for NTG progression.

RESULTS: The average follow-up period was 12.2 years, and 56 of 121 eyes (46.3%) showed the NTG progression. Kaplan-Meier analysis revealed that upper tertile group (percentage IOP reduction >22.1%) showed a greater cumulative probability of non-progression than lower tertile group (percentage IOP reduction < 13.3%; p = 0.012). Multivariate Cox's proportional hazard model indicated that percentage reduction of IOP (HR = 0.964; p = 0.007) and the occurrence of disc haemorrhage (HR = 2.410; p = 0.008) were significantly associated with NTG progression.

CONCLUSIONS: The amount of IOP reduction using topical medications was related to NTG progression, and lower percentage reduction in IOP was a consistent risk factor for progression.