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Editors Selection IGR 12-3
Surgery: IOP reduction after phaco
Comment by Richard Lee on:
26781 Phacoemulsification with artificial lens implantation: A technique for prevention and treatment of adult glaucoma, Poley BJ; Lindstrom RL; Samuelson TW et al., Techniques in Ophthalmology, 2010; 8: 48-54
Phacoemulsification cataract surgery with intraocular lens implantation (phaco/IOL) has long been suggested to modestly and temporarily lower the intraocular pressure (IOP). However, recent reports have suggested phaco/IOL lowers the IOP more and for a longer period than previously believed ‐ to the point where some cataract surgeons have jokingly suggested they have always also been glaucoma surgeons. Poley et al. (1463) review their experience with phaco/ IOL and its effect on the IOP in addition to providing hypotheses on why this IOP lowering occurs with phaco/IOL.
In their retrospective review of 588 non-glaucoma and 124 glaucoma eyes which underwent phaco/IOL, the authors observed that the IOP decreased after cataract surgery in an IOP-dependent manner without regard to glaucoma status for up to ten years ‐ much longer than the six to twelve months that was suggested in the early literature. Interestingly, a higher pre-operative IOP was associated with a greater reduction in the IOP (from 29-15 mmHg). However, at IOPs less than 15 mmHg, the IOP lowering effect was no longer evident and was actually slightly higher on average than the pre-operative IOP.
Age was not associated with IOP reduction with cataract extraction, although the authors suggest the mechanism of elevated IOP is secondary to a phacomorphic component of progressive angle narrowing affecting trabecular outflow. However, the authors also discuss how the lens increases in size and hardness with age, so it would have been interesting to determine within their data set if higher IOPs were associated with thicker lenses and age versus their analysis which showed age did not affect IOP lowering with cataract surgery. In addition, the type of glaucoma was not assessed in this review ‐ it is quite possible that certain types of glaucoma (i.e., pseudoexfoliation glaucoma with progressively narrower angles with zonular weakness associated with age) may respond with greater IOP reduction than other forms of glaucoma with phaco/IOL.
Phaco/IOL may be a reasonable and important part of the treatment armamentarium for treating ocular hypertension and for lowering the IOP in certain glaucoma patients
Poley and colleagues remind ophthalmologists that phaco/IOL may be a reasonable and important part of the treatment armamentarium for treating ocular hypertension and for lowering the IOP in certain glaucoma patients which may be a safer alternative to glaucoma filtering surgery. This finding needs to be studied further using imaging (i.e. ultrasound biomicroscopy, OCT) to prognostically determine how the IOP may be affected by anterior segment changes secondary to phaco/IOL as a IOP-lowering therapeutic, in addition to improving the quality and quantity of vision.
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