Self-tonometry to manage patients with glaucoma and apparently controlled intraocular pressure

We tested a self-tonometer than can be used by the patient alone to monitor intraocular pressure (IOP) in a normal environment. The instrument is safely and easily used after training. Normal subjects and patients with glaucoma who had an IOP of 22 mm Hg or less at three consecutive visits were referred for diurnal monitoring. After successful training, they received a self-tonometer and instructions to obtain five measurements daily between awakening and bedtime for three to six days. More than half the patients had one or more readings above 22 mm Hg. About half of the IOP peaks occurred at times outside of normal office hours. Interestingly, more elevated IOP readings were recorded in patients with suspected or documented progression of glaucomatous damage than in patients thought to be stable or in normal subjects. In eyes that have already sustained glaucomatous damage, the progression may be explained by the presence of previously undocumented IOP peaks. Valuable additional clinical information can be gained by diurnal IOP monitoring, and the self-tonometer is a practical tool for its measurement.