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Insights from IOP data

After beginning a program of self tonometry, it is important to understand and determine what to do with the documented results from one's IOP readings. The act of taking and collecting measurements, has no real benefit without a goal in mind, and those goals are what we consider in this article.


Diurnal Patterns

One of the most important results from the IOP data will be found in the patterns seen with the diurnal and nightly variations in pressure. It is well recognized that with glaucoma and ocular hypertension patients, the highest pressures and spikes usually occur in the very early morning hours (often during sleeping hours), upon just awakening, and within an hour or so after waking. It is not completely understood why, but pressure elevations which occur after waking are thought to be the result of the normal release of cortisol. In a non glaucoma patient, the eye is able to handle these physiological factors, but with the glaucoma patient, this is not so.

Some FitEyes members also find the natural diurnal pattern to show a pressure rise later in the afternoon (which may subsequently go down around dinner time). Usually, the afternoon or late night pressures just before bedtime tend to be the lowest. These are general observations, but many who practice tonometry find deviations from these patterns. For example, 'Sally' reports that her first waking and early morning pressures are no different than at other times. 

It needs to be pointed out here that patterns need to be observed for a considerable period of time in order to weed out other confounding variables. For example, there may be activities at certain times of the day which may have an effect on pressures, but do not reflect the true diurnal or biological cycles. One of the most important findings - for those who are able to measure via a portable tonometer - are how eye pressures behave at night. The studies demonstrate that this is when most glaucoma damage occurs.

Activities Which Affect Eye Pressures

Much of what we will write about here overlaps with our article The evolution of a self-tonometrist, and therefore, we recommend reviewing that article.  In addition to understanding how basic diurnal bio-rhythms affect IOP, it is equally important to gain insight into the effect of one's daily routines and activities on pressure. These include any number of things, including exercise, computer use, sports, reading, etc. 

How high the highs, and how low the lows?

As pointed out in related FitEyes articles, one of the most important priorities, are the patterns which correspond to the highest pressures. The management of these pressures may initially involve additional or alternative drops (or possibly other medical procedures). However, there are often behavioral interventions which can enormously affect pressure once these periods are recognized. There will also be times when the pressures run the lowest, and observing these and surrounding circumstances, will be invaluable in working toward maximizing relevant factors. Of course, if low pressures are simply the result of the time of day, there is not much to be done. However, there are usually additional circumstances relating to low pressures which can be explored.

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