Cataract Surgery and Intraocular Pressure

Introduction

Cataract surgery has been shown to cause a reduction in intraocular pressure (IOP) months to years after surgery.^[1] However, a known side effect in the early postoperative period, especially within 24 hours of surgery, is a rise in IOP.^[2] Causes of this elevation in IOP include retained lens material, postoperative inflammation, and retention of viscoelastic substances within the anterior chamber. With the potential risks caused by sudden pressure spikes, the possibility of a postoperative elevation in IOP is of particular concern for patients with glaucoma who are considering cataract extraction. This prospective, randomized trial compared the short-term effect of cataract surgery on IOP in patients with and without glaucoma.

Levkovitch-Verbin H, Habot-Wilner Z, Burla N, et al
Ophthalmology. 2008;115:104-108

Summary

The authors studied 122 patients with healthy eyes, glaucoma, and exfoliation syndrome who underwent uncomplicated phacoemulsification surgery. All patients were randomized to receive either a postoperative drop of timolol 0.5% or no treatment. IOP was measured at 4, 8, and 24 hours after surgery.

The IOP in normal subjects was significantly lower following surgery than the IOP in patients with exfoliation syndrome and glaucoma. The elevation in IOP in these patients was seen primarily at the 4-hour timepoint. The use of timolol (1 drop at the completion of surgery) significantly lowered IOP in patients with glaucoma but did not alter it in those with exfoliation syndrome or normal subjects. Markedly elevated IOP (greater than 25 mm Hg) occurred in patients with glaucoma (nearly 75% of the time) and exfoliation syndrome (5%), but it did not occur in normal subjects. Timolol reduced the occurrence of markedly elevated IOP in both the glaucoma and exfoliation groups.

Comment

This study suggests that patients who undergo cataract surgery and have no history of glaucoma or exfoliation syndrome are unlikely to develop a clinically important spike in IOP in the postoperative period. However, patients with glaucoma and exfoliation syndrome may have elevated IOP that may be averted by topical pressure-lowering agents at the completion of surgery. It is not clear whether spikes of IOP are more important than the level of sustained IOP in causing progressive optic nerve head damage; however, most would suggest that avoidance or treatment of this type of spike in pressure would be best. It is also thought that patients with more severe glaucoma and more severe visual field loss are at increased risk for progression, including the possibility of central and paracentral visual loss, with a postoperative spike in IOP.

This study did not attempt to distinguish any difference in efficacy of postoperative IOP-lowering agents; timolol, chosen in part because of its rapid onset of action, was the only agent used.

Abstract

Medscape Ophthalmology © 2008  Medscape

Cite this: Cataract Surgery and Intraocular Pressure - Medscape - Apr 24, 2008.