M. Rosner

Prevention of Posterior Capsule Opacification With the CO2 Laser

BACKGROUND AND OBJECTIVE 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. MATERIALS AND METHODS 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). RESULTS 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. CONCLUSION 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.

Sclerotomy using needle puncture and subconjunctival injection of mitomycin C

OBJECTIVE To explore the possibilty of creating a temporary sclerotomy using a 26-gauge needle and sustaining its patency by injectiong 0.1 mL of 0.1 mg/mL of mitomycin C (MMC). ANIMALS AND METHODS Twenty-four New Zealand white rabbits were randomized into 3 groups. In the test group, puncture was performed using 26-gauge needle penetrating the anterior chamber at the limbus, and 0.1 mg/mL MMC were injected subconjunctivally. In the control group, a puncture was performed in the same fashion and in the MMC group, MMC only was injected subconjunctivally. Intraocular pressure (IOP) was measured prior to surgery and at days 1, 3, 7, 10, 14, 21, and 28. RESULTS The mean intraocular pressure in eyes that underwent puncture with application of MMC was significantly lower than the IOP in the eye at all measurements up to and including day 21. In the puncture group, pressure was significantly lower than in the fellow eye only at day 3. No significant pressure reduction was observed at any measurement interval in eyes treated with MMC only. CONCLUSION This simple technique of subconjunctival puncture of the limbus combined with application of MMC was effective in lowering IOP in rabbits. This may serve to attain a temporary filter in patients who need strict short-term pressure control.