IOP: Quantity and Quality

IOP reduction has been firmly established as effective treatment for glaucoma, as proven in a number of well conducted, prospective, randomized clinical trials. (1,2,3,4,5,6) Here we consider an aspect of the “quality” of IOP: its variation. There is accumulating evidence that, at least in some patients, IOP variation is a separate and important risk factor for glaucomatous damage. IOP variation over time may be divided into diurnal fluctuation that occurs on a daily basis, short-term IOP fluctuation that occurs over days to weeks, and long-term IOP fluctuation that occurs over months to years. In practice, IOP variation is usually quantified as inter-visit IOP variation with IOP measurements being made sequentially during office hours over a long period of time. While this inter-visit IOP variation primarily serves as a surrogate for long term IOP fluctuation, it likely contains some component of diurnal and shortterm fluctuation.