Tip of the Month
Publishing date: October 2012
Tip Editors: Ann Hoste, John Salmon and John Thygesen
Tip reviewer: Roger Hitchings
The Science behind the Tip
Raised intraocular pressure (IOP) in an eye with pseudoexfoliation syndrome results from pigment and exfoliation material in the trabecular meshwork reducing aqueous outflow. In unilateral disease, the eye with pseudoexfoliation almost always develops a cataract before the fellow eye, presumably as a consequence of low ascorbate levels in the anterior chamber of these individuals (1). Removing the cataract can result in a late, sustained reduction in IOP, possibly as a consequence of reduced irido-lenticular touch and a reduction in debris in the trabecular meshwork.
The higher the preoperative IOP the greater the reduction in postoperative IOP (2). The IOP-lowering effect has been related to the volume of irrigation fluid used at the time of surgery (3). When the phacoemulsification is combined with aspiration of material from the trabecular meshwork an average reduction of 14 mmHg at 2 years has been reported (4). The beneficial effect can last up to 7 years (2).
Contributor: John Salmon, Oxford
1. Koliakos GG, Konstas AG, Schlotzer-Schrehardt U et al. Ascorbic acid concentration is reduced in the aqueous humor of patients with exfoliation syndrome. Am J Ophthalmol. 2002; 134:879-83.
2. Shingleton BJ, Laul A, Nagao K et al. Effect of phacoemulsification on intraocular pressure in eyes with pseudoexfoliation: single surgeon series. J Cataract Refract Surg. 2008; 34:1834-41.
3. Damji KF, Konstas AG, Liebmann JM et al. Intraocular pressure following phacoemulsification in patients with and without exfoliation syndrome: A 2-year prospective study. Br J Ophthalmol. 2006; 90:1014-8.
4. Jacobi PC, Dietlein TS, Krieglstein GK. Bimanual trabecular aspiration in pseudoexfoliation glaucoma: an alternative in nonfiltering glaucoma surgery. Ophthalmology. 1998;105:851-94.