Efficacy of one drop of 2% pilocarpine to reverse the intraocular pressure peak at 6:00 a.m. in early glaucoma

Purpose: To assess the efficacy of one drop of 2% pilocarpine (2% Pi) at night to reverse the intraocular pressure (IOP) peak at 6:00 a.m. in the daily curve of intraocular pressure (DCPo) of pre-perimetric open-angle glaucoma. Methods: We retrospectively analyzed the charts of patients with early glaucoma. We compared the IOP values at 6:00 a.m. in the same eye of two DCPos. In the first DCPo the patients were without medication, and in the second they were using one drop of 2% Pi between 10:00 and 10:30 p.m. for at least six months. Each DCPo had five IOP measurements taken at 9:00 a.m., 12:00, 6:00 and 10:00 p.m. (Goldmann applanation tonometer) and in the morning of the following day at 06:00 a.m. (Perkins tonometer) in a supine position in bed and in darkness before the patient had stood up. The pre-perimetric glaucoma patients, without medication, presented an IOP peak at 6:00 a.m. in the DCPo. This peak represents a difference ≥7 mmHg between the IOP value at 6:00 a.m. and that lesser IOP at any other time in the DCPo. An IOP peak reversion at 6:00 a.m under 2% Pi occurred when the difference between the IOP at 6:00 a.m. and the lesser IOP was ≤5 mmHg in the DCPo. Patients with secondary glaucoma were excluded. We set the significance level at 5% (P