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The study by Mansberger et al. shows that cataract surgery with IOL implantation, lowers IOP by 20% in 40% of eyes with untreated ocular hypertension (as characterized in the OHTS). It should also be noticed that 17.5% had a very small (0 to 9%) decrease in IOP, and even 11% had an increased IOP (0.7%-18.3%). Although IOP decreased for up to 36 months post surgery, a slight trend for IOP increase can be seen in Figure 2 of the paper. Also, the higher the preoperative IOP, the greater the reduction achieved.
This is very interesting data obtained from a well designed and conducted trial. There is no information regarding cataract surgery technique, surgical or post-operative complications or type of IOL used. Different studies have addressed the issue of IOP reduction after cataract surgery in patients with glaucoma and ocular hypertension.1,2 A recent paper found an even greater reduction in IOP after cataract extraction in the control group of patients with early glaucoma or ocular hypertension, but hypotensive medications were allowed to be used.2 Also, direct comparison with other papers is difficult due to different study designs, patient populations, preoperative IOP levels, among other factors.
Mansberger et al. use in their study a unique and well-defined patient population that did not receive ocular hypotensive therapy and had no prior laser peripheral iridotomies. It is important, as the authors point out, not to extrapolate these results to other populations, including glaucoma patients.