Objective: To investigate whether eyes with glaucoma or exfoliation syndrome without glaucoma are prone to exhibit intraocular pressure (IOP) elevation shortly after cataract surgery and, if so, whether timolol maleate 0.5% reduces these spikes.

Methods: Prospective randomized double-masked clinical trial. Methods: One hundred twenty-two patients with normal eyes, medically well-controlled glaucoma, or exfoliation syndrome who underwent uneventful phacoemulsification cataract extraction. Methods: Patients were randomly assigned to an immediately postoperative drop of either timolol maleate 0.5% or no treatment. Intraocular pressure was measured preoperatively and 4, 8, and 24 hours and 1 week later. Methods: Intraocular pressure measurements.

Results: The changes in postoperative IOP over time differed significantly between glaucoma, exfoliation syndrome, and normal (P = 0.005). Intraocular pressure was significantly lower in the normal group (n = 25) than in both the glaucoma (n = 18) and exfoliation syndrome (n = 19) groups (P<0.001). With 1 drop of prophylactic timolol maleate 0.5% at completion of surgery, the normal group (n = 25) again had IOP significantly lower than those of the glaucoma (n = 15) and exfoliation syndrome (n = 20) groups (P<0.001). Treatment with timolol maleate 0.5% significantly changed postoperative IOP over time in the glaucomatous eyes (P = 0.003), but it made no difference in the exfoliation syndrome (P = 0.4) or normal (P = 0.5) eyes. Intraocular pressure > 25 mmHg did not occur among normal eyes. Intraocular pressure > 25 mmHg and > 30 mmHg occurred in 10 (55%) and 5 (28%) glaucoma patients, respectively, and 5 (27%) and 2 (11%) exfoliation syndrome patients, respectively. Timolol maleate 0.5% eliminated IOP spikes > 30 mmHg and reduced the frequency of IOP > 25 mmHg in both groups to 14% in the glaucoma group and 5% in the exfoliation syndrome group. Most IOP elevation occurred at 4 hours postoperatively. The mean IOP was <20 mmHg in all groups 1 day postoperatively.

Conclusions: Medically well-controlled glaucoma patients and patients with exfoliation syndrome may experience IOP elevation shortly after cataract surgery. Instillation of timolol maleate 0.5% at the end of the procedure in this series eliminated IOP > 30 mmHg, but IOP elevation below that level can still occur.