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Updated: Jul 20, 2026

Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye
Published on: June 20, 2015
Evaluation of intraocular pressure in the immediate period after phacoemulsification
B J Shingleton1, R A Wadhwani, M W O'Donoghue
1Ophthalmic Consultants of Boston, Center for Eye Research and Education, Boston, Massachusetts 02114, USA.
Purpose:
To determine the incidence of hypotony or intraocular pressure (IOP) spikes in the early period after clear corneal phacoemulsification in normal and glaucomatous eyes.
Setting:
Ambulatory surgical center.
Methods:
This retrospective analysis comprised 112 eyes that had clear corneal phacoemulsification. Postoperative IOP measurements were collected 30 minutes, 1 day, and 1 month after surgery.
Results:
Twenty-three eyes had an IOP of 5 mm Hg or below 30 minutes postoperatively. The IOP at 30 minutes was lower than at 1 day in both the normal and the glaucoma group. The mean IOP in the normal group was 10.0 mm Hg +/- 4.3 (SD) at 30 minutes and 16.9 +/- 4.4 mm Hg at 1 day (P < or = .005). The means in the glaucoma group were 9.6 +/- 3.9 mm Hg and 16.9 +/- 5.7 mm Hg, respectively (P < or = .0002). The IOPs at 30 minutes and 1 day were not significantly different between the 2 groups.
Conclusions:
A significant percentage of eyes having clear corneal phacoemulsification had an IOP of 5 mm Hg or less 30 minutes after surgery. Even though there were no postoperative complications from hypotony and there was a relative absence of significant IOP elevation 1 day postoperatively, the frequency of low IOP at 30 minutes suggests that consideration be given to leaving postoperative eyes with a higher IOP at the completion of phacoemulsification rather than with the estimated 10 mm Hg tactile IOP strived for in this study.
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