IOP may increase with age in NTG patients. Photo: Jennifer Sanderson, OD, Andrew Rixon, OD, and James Williamson, OD.
IOP may increase with age in NTG patients. Photo: Jennifer Sanderson, OD, Andrew Rixon, OD, and James Williamson, OD. Click image to enlarge.

Researchers recently reported a continuous decrease of IOP throughout 20 years of normal-tension glaucoma (NTG) patient data. IOP was at its highest in the oldest group and lowest in the study’s youngest group. All groups were accompanied by distinct seasonal variation.

The study retrospectively extracted 49,007 data points from the medical records of 1,774 NTG patients (665 males and 1,109 females; mean age: 59.8 years; mean observation period: 5.6 years follow-up) from the Kyoto Prefectural University of Medicine Glaucoma Registry (KPUM-GR) database. The research team then categorized the data into five groups of four consecutive years each (1997 to 2000, 2001 to 2004, 2005 to 2008, 2009 to 2012 and 2013 to 2016).

The annual mean IOP was 13.9mm Hg in the 1997 to 2000 group, with a gradual decrease in each subsequent group, amounting to 12.3mm Hg in the most recent group, 2013 to 2016. This change, although statistically significant, may not be clinically significant and may fall within inter-rater variability in IOP measurement.

“A subset of patients would presumably have developed other conditions during the 20-year study period, which is expected in a large study population such as patients with diabetic retinal disease, age-related macular degeneration, etc., and those additional ocular conditions and/or their specific treatment courses may lead to changes in IOP over time,” the researchers suggested.

“There were some confounding factors for the IOP seasonal variation that could not be addressed due to the fact there was no related data in the KPUM-GR, such as dry eye disease, which is usually worse in winter, or seasonal patterns in the adherence to prescribed medications.”

The researchers concluded that the findings in this study clearly indicate the potential of real-world data to elucidate latent information via the appropriate use of big data.

Ikeda Y, Mori K, Ueno M, et al. Seasonal variation and trend of intraocular pressure decrease over a 20-year period in normal-tension glaucoma patients. Am J Ophthalmol. October 11, 2021. [Epub ahead of print].