BACKGROUND AND OBJECTIVE: Posterior capsule opacification (PCO) is a common
complication after cataract extraction, despite the modern surgical techni
ques and lenses being used for this procedure. Its prevention challenged ma
ny investigators, because the current treatment of choice, capsulotomy with
Nd:YAG laser, is associated with sight-threatening complications. In the p
resent study, the authors investigated two approaches of preventing PCO usi
ng 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 chambe
r was filled with either air or a viscoelastic substance, and laser burns w
ere applied to the equator of the lens capsule and to the peripheral anteri
or capsule to destroy the epithelial cells. In the capsulotomy study, a pri
mary 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 ant
erior chamber with air. In rabbit eyes, however, it was technically impract
ical to work with air. Using a viscoelastic material to maintain the anteri
or chamber, the hollow probe of the CO2 laser becomes plugged up and theref
ore is unable to affect the ocular tissue. However, by combining viscoelast
ic and air pumping, both the destruction of the lens epithelial cells and t
he creation of a central posterior opening behind a capsular-fixated IOL wa
s repeatedly achieved.
CONCLUSION: Using the CO2 laser for destruction of lens epithelial cells an
d the creation of controlled posterior capsulotomy is feasible and practica
l. A different design of the probe (closed gauge) is required to enable it
to operate clinically in a fluid or viscoelastic environment.