Cataract surgery in eyes with glaucoma

ByUday Devgan, MD

There are now multiple studies that show cataract surgery helps to lower IOP in eyes with glaucoma. And for many patients, the best initial glaucoma surgery may actually be our tried-and-true cataract surgery. But what about performing cataract surgery in eyes that have already had glaucoma surgery?

Cataract surgery in an eye with prior glaucoma surgery.

Intraoperatively, the primary difficulty is the balance of fluidics.

In phacoemulsification, we want to keep the inflow of fluid greater than the outflow of fluid in order to maintain the anterior chamber and keep the posterior capsule away from our instruments. Fluidic surge is simply the condition when, even for a fraction of a second, the outflow of fluid is more than the inflow. This can lead to instability of the anterior chamber and rupture of the posterior capsule.

In eyes with prior glaucoma surgery, there is an additional outflow tract for our irrigating fluid. This means that at any given time, the outflow of fluid is greater than we're used to. To rebalance the inflow:outflow ratio, we can increase the inflow, decrease the outflow, or both.

To increase the inflow, the infusion bottle is raised so that the effect of gravity is greater and the inflow pressure is increased. To decrease the outflow, we can lower the flow rate from a peristaltic pump, keep our incisions tighter so they don't leak, and limit the flow through the glaucoma surgical site. In eyes with seton shunts, this may entail placing a temporary suture in or around the tube to limit outflow. In eyes with trabeculectomies, a bolus of viscoelastic can be placed to act as a barrier to outflow. At the end of surgery, the suture is removed or the viscoelastic is aspirated and these patients tend to do very well.

Get more expert perspective from Dr. Devgan live at Hawaiian Eye 2010, to be held January 17-22, 2010 at the Grand Hyatt Kauai. Learn more at OSNHawaiianEye.com.