[How to ensure that glaucoma is stable? Intraocular pressure]

Abstract

In patients with open-angle glaucoma, intraocular pressure (IOP) obtained through treatment should guard against the progression of glaucoma damage. This depends on the initial state of intraocular pressure, but also on the stage of glaucoma, how fast the alterations are progressing, the patient's age and life expectancy, as well as the presence of other risk factors. To determine the ideal level of treated IOP, the term "target pressure" is often used. This term is very much open to criticism, however, because it calls on a static figure for what is highly variable biological information belonging to the body's biological rhythms. A large number of formulas are used to calculate this target pressure number, but all of them come up against the disadvantage of not taking into account the variations in IOP during the day/night cycle. Yet it is these very variations that can characterize the severity of the disease in terms of IOP. In a glaucoma patient, the IOP curve plotted over 24 h has higher IOP values during the day than at night, contrary to a healthy subject. Fluctuations of more than 10 mmHg are not rare during the day/night cycle, most often with many peaks, which are deleterious for retinal nerve fibers. These dynamic pressure parameters are essential both in determining the therapeutic strategy and in evaluating the effectiveness of treatment. In practice, with any case of open-angle glaucoma and before any treatment is given, a diurnal curve should be established. Six to eight measurements between 8 AM and 6 or 8 PM should be enough. They should be carefully combined with concomitant measures of systemic blood pressure. Once treatment has started, we suggest that a new diurnal curve be established 1 month and then 4 months after the beginning of treatment. The treatment will be modified if needed, based on IOP criteria established at 1 month, and on IOP, perimetric, and anatomic criteria determined again at 4 months. If the disease continues to worsen despite a satisfactory diurnal IOP, IOP should be measured over 24 h, associated with Holter monitoring, looking for an escape of pressure at night.