INDIVIDUAL VARIABILITY IN THE DIURNAL INTRAOCULAR-PRESSURE CURVE

Background. Reduction of intraocular pressure (IOP) is a primary goal of most glaucoma treatments. However, because the IOP varies during th e day, single measurements performed in an ophthalmologist's office do not necessarily provide information on the peak level and fluctuation of the IOP. Methods: Home tonometry was performed to gain more inform ation on the nature of the diurnal IOP curves and on their variability . One hundred seventy-six patients with open-angle glaucoma (OAG), 55 subjects with ocular hypertension (OHT), and 18 control individuals me asured their IOP five times daily at home for 4 to 8 consecutive days using a self-tonometer. Results: Well-defined diurnal IOP variations w ere observed in all three groups with a predominance of curves with mo rning or mid-day maxima. Erratic IOP curves without a diurnal rhythm w ere present in OHT (22%) and OAG (16%) patients but not in control sub jects. Differences between the curves of the two eyes of an individual were frequent in OHT (33%) and OAG (36%) patients but not in control subjects (6%). Finally, the majority of OHT (72%) and OAG (66%) patien ts showed a difference in their diurnal curve patterns on repeat home tonometry performed months apart. Conclusion: The authors indicate tha t it is difficult to rely on one eye as a control for the other. They also indicate that changes in IOP observed in the office at different visits often may be due to a shift in the type of diurnal curve rather than to a true change in the mean IOP. Monitoring of the diurnal IOP may be necessary in some cases if the clinician relies, even partially , on the level of IOP when making a decision on patient management.