All areas of medicine are undergoing important innovations, and the primary movement is in the direction of individualized medicine.
This individualization also is evident to the clinical level, where consideration is being given to personalizing IOP levels in patients with fluctuating IOPs and using diurnal IOP fluctuation data to treat glaucoma and set target pressures.
The American Academy of Ophthalmology Preferred Practice Pattern recommends a blanket approach to IOP reduction—i.e., that the IOP should be reduced by 20% to 30% in order to avoid damage to the visual fields in patients with primary open-angle glaucoma (POAG) followed by monitoring of the structure and function of the optic nerve if treatment adjustments are needed.
With this generalized approach, the challenge is determining the appropriate target IOP, according to Anne Louise Coleman, MD, PhD.
“When setting the target pressure, there are many factors to consider, and unfortunately, the percent reduction might not always be 20% to 30%,” said Dr. Coleman, the Fran and Ray Stark Foundation Professor of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, UCLA, Los Angeles.
“Clinicians must consider the type of glaucoma, visual field loss, nerve damage, progression rate, corneal properties, and the risk profile that includes age, race, family history, and IOP fluctuations,” she added.
A caveat regarding management of IOP is that clinicians should not put all of their stock into one IOP measurement, despite the fact that the population-based and epidemiologic glaucoma studies view one measurement as important and reliable.
A one-time IOP measurement can be misleading and can be a poor indicator for diagnosis and treatment, Dr. Coleman noted.
In individual patients, the IOPs, like blood pressure, can vary substantial from one hour to the next and from one day to the next because of the measurement reproducibility, patient activity levels, fluid intake, body position, and circadian rhythm.
“Many factors can influence that one-time pressure reading,” she said.
Large fluctuations in IOP seem to be a risk factor for progression of visual field damage.
Dr. Coleman cited a study by Asrani and colleagues (J Glaucoma. 2000;9:134-142) that evaluated 64 patients with POAG who measured their IOP at home five times daily for 5 days during waking hours. All patients had an IOP under 25 mm Hg and were followed for a minimum of 1 year (mean, 5 years).
“The investigators found that larger pressure fluctuations were a risk factor for visual field progression that was independent of all the parameters that were obtained in the office including the baseline IOP and visual field damage,” Dr. Coleman said.