24-hour monitoring of intraocular pressure in glaucoma management: A retrospective review

Purpose: Diurnal variation in intraocular pressure (IOP) is well recognized, yet important decisions in glaucoma management are frequently made after 1 or 2 IOP measurements. Twenty-four-hour monitoring of IOP may identify IOP variation and spikes. This study determined the value of 24-hour IOP monitoring in routine clinical practice. Methods: Data were acquired retrospectively from case notes of 29 glaucoma patients sequentially admitted for 24-hour IOP monitoring while taking their established antiglaucoma therapy. Results: While there was no difference between the mean clinic (office) and mean 24-hour IOP measurements, the peak IOP during 24-hour monitoring was on average 4.9 mm Hg higher than the peak clinic IOP (P<0.0001). In 4 (13.8%) patients, the peak IOP over 24 hours was at least 12 mm Hg higher than the clinic peak. Peak IOP values occurred outside normal office hours in 51.7% of patients. Twenty-four-hour IOP monitoring resulted in a change of clinical management in 23 (79.3%) patients, including 13 (44.8%) who were offered trabeculectomy. Conclusion: Twenty-four-hour monitoring of IOP frequently led to a change of glaucoma management by identifying IOP fluctuations and spikes. High IOP and wide diurnal IOP variation are considered major risk factors for glaucoma progression, and standard clinic follow-up evaluations failed to identify these phenomena.