Short-term effect of topical brimonidine tartrate on intrastromal corneal pressure in rabbits

Because topical brimonidine tartrate has been reported to decrease flap adherence in the early postoperative period after LASIK, its effect on the intrastromal corneal pressure (ICP) was evaluated.

An interventional, prospective, animal study was performed. Intrastromal corneal pressure was recorded for 45 minutes in eight eyes of rabbits treated with topical brimonidine tartrate three times daily for 3 consecutive days (study group); eight contralateral eyes were treated with artificial tears (control group). All measurements were performed by the same, masked investigator.

Mean ICP was -4.00 +/- 2.90 mmHg, -6.70 +/- 3.00 mmHg, and -9.00 +/- 4.50 mmHg at 15, 30, and 45 minutes, respectively, in the control group. In the study group (brimonidine-treated eyes), the ICP readings were +2.75 +/- 2.90 mmHg, -2.50 +/- 13.00 mmHg, and -8.50 +/- 5.00 mmHg at the same time points, respectively. The differences in the ICP between both groups were statistically significant at 15 minutes (P = .01), but no significant difference was found at 30 or 45 minutes (P = .20 and P = .80, respectively).

Topical treatment with brimonidine tartrate induces a significant decrease in ICP at 15 minutes. This effect on ICP may explain the decreased corneal flap adherence reported in eyes treated with this drug.