APR 02, 2008
Nd:YAG laser posterior capsulotomy is a common procedure used by general ophthalmologists to treat secondary cataracts of the posterior capsule following cataract surgery. This procedure has been known to cause intraocular pressure (IOP) spikes in some normal patients in the short term. Of particular concern is IOP elevation in glaucoma patients both in the short and long term. The aim of this study was to evaluate the long-term IOP control of glaucomatous eyes following Nd:YAG laser capsulotomy.
The study's researchers retrospectively reviewed the cases of 69 glaucoma patients who underwent Nd:YAG capsulotomy following cataract extraction or a combined cataract-glaucoma procedure over a three-year period. The patients were followed for a minimum of six months and median of 24 months. IOP control, the number of glaucoma medications required, and the need for additional pressure-lowering surgical procedures were evaluated. Specifically, the researchers noted the presence of "disease progression," which they defined as the occurrence of any of the following: IOP rise of more than 5 mm Hg on two consecutive visits, the addition of one or more glaucoma medications, and additional glaucoma surgery. Kaplan-Meier event rate curves were used to map the results.
It was clear that disease progression occurred within this patient group. The rate was measured as 11.6% four months after Nd:YAG capsulotomy, 20.3% after six months, 38.1% after 12 months, 46.1% after 24 months, and 52.1% after both 36 months and 47 months.
This loss of baseline IOP control and the need for more aggressive therapy is common in glaucoma patients following Nd:YAG capsulotomy. It is unclear whether this rise is related directly to the use of the laser or to the natural progression of the disease. However, owing to the known increase in IOP following capsulotomy in existing glaucoma patients, the study recommends close monitoring for the first two years after the procedure, after which time the group IOP curve flattens.
The strengths of the study were that it included uniform inclusion criteria, objective outcome measures, and a long follow-up period. However, because it was conducted respectively, there was no control group. A control group, in this case, would have included those patients with glaucoma with a secondary cataract who did not undergo Nd:YAG capsulotomy. But, of course, conducting such a study is not an ethical possibility.