Prevention of posterior capsule opacification with the CO2 laser

Posterior capsule opacification (PCO) is a common complication after cataract extraction, despite the modern surgical techniques and lenses being used for this procedure. Its prevention challenged many investigators, because the current treatment of choice, capsulotomy with Nd:YAG laser, is associated with sight-threatening complications. In the present study, the authors investigated two approaches of preventing PCO using the CO2 laser.

A 15-W CO2 laser with a 17- or 18-gauge hollow probe was used on 20 sheep eyes and 14 rabbit eyes. Lens extraction was done by phacoemulsification. In the equatorial treatment study, the anterior chamber was filled with either air or a viscoelastic substance, and laser burns were applied to the equator of the lens capsule and to the peripheral anterior capsule to destroy the epithelial cells. In the capsulotomy study, a primary posterior capsulotomy was created by delivering 1 to 3 laser shots to the capsule behind an implanted intraocular lens (IOL).

The CO2 laser was satisfactory in sheep eyes after filling the anterior chamber with air. In rabbit eyes, however, it was technically impractical to work with air. Using a viscoelastic material to maintain the anterior chamber, the hollow probe of the CO2 laser becomes plugged up and therefore is unable to affect the ocular tissue. However, by combining viscoelastic and air pumping, both the destruction of the lens epithelial cells and the creation of a central posterior opening behind a capsular-fixated IOL was repeatedly achieved.

Using the CO2 laser for destruction of lens epithelial cells and the creation of controlled posterior capsulotomy is feasible and practical. A different design of the probe (closed gauge) is required to enable it to operate clinically in a fluid or viscoelastic environment.