Trend of continuous intraocular pressure decrease over a 20-year period in Japanese normal tension glaucoma patients

Abstract

Purpose : We first established our original Kyoto Prefectural University of Medicine Glaucoma Registry (KPUM-GR) in 1995, and have continued inputting data since then. The purpose of this study was to analyze the data in the KPUM-GR and investigate the annual trend and seasonal variation of intraocular pressure (IOP) over the past 20 years in Japanese normal tension glaucoma (NTG) patients.

Methods : IOP data was extracted from the KPUM-GR data obtained at the KPUM Hospital and affiliate clinics under the following conditions: 1) 1 data point per patient per month, 2) if bilateral data was available, the right-eye data was used, 3) if measured more than twice within 1 month, the mean IOP data was calculated and used, and 4) if the patient had undergone glaucoma surgery, the postoperative data was excluded, but not excluded if cataract surgery or laser treatment, such as trabeculoplasty, was performed. In order to investigate the trends of IOP throughout the 20-year period, we first calculated the mean IOP from all available data of each month from January 1997 through December 2016. The data was then further divided into 5 groups of 4 consecutive years each (1997-2000, 2000-2004, 2005-2008, 2009-2012, and 2013-2016), and the mean IOP of each month within each group was then calculated. Seasonal variations of IOP over the 20-year period and in the 5 consecutive 4-year groups was then investigated via nonlinear multiple regression analysis.

Results : We ultimately extracted 49,007 independent data points derived from 1,774 Japanese NTG patients (665 males and 1,109 females; mean age: 59.8 ± 14.4 years, mean observation period: 5.6 ± 4.4 years) treated with/without anti-glaucoma medications over the 20-year period. A continuous decrease of IOP, with seasonal variations, was detected throughout the 20-year period (p<0.001). Annual mean IOP was highest (13.9 ± 2.7 mmHg) in the oldest 4-year group (1997-2000), followed by a gradual decrease in each subsequent group, finally becoming lowest (12.3 ± 2.7 mmHg) in the most recent group (2013-2016) (trend test: p<0.001). The seasonal variations of IOP were clearly detected (p<0.001) in each of the 5 consecutive 4-year groups.

Conclusions : Based on real-world longitudinal data, our findings revealed a continuous decrease and seasonal variations of IOP throughout the 20-year period in Japanese NTG patients.

This is a 2021 ARVO Annual Meeting abstract.