In light of research showing adequate IOP-lowering effects of cataract surgery alone, do you think combined procedures are still viable? If so, why?

Issue: April 25, 2009

Combined surgery still viable treatment option

James C. Tsai

While cataract surgery alone appears to lower IOP in a substantial number of cases, I believe that the combined cataract/glaucoma procedure is still a viable and useful treatment option in a significant number of patients with moderate to severe glaucoma. Specific situations include those patients with inadequate IOP control despite maximum tolerated medical and/or laser therapy. Moreover, the combined procedure should be considered in patients with mild to moderate glaucoma who have anticipated difficulty with postoperative IOP control. Other indications include a visually significant cataract in the presence of an existing inadequate or failed filtering bleb.

While trabeculectomy is often the glaucoma surgery combined with cataract surgery, other glaucoma procedures may be substituted, including aqueous shunt implants, the Ex-PRESS shunt (Optonol), the Trabectome (NeoMedix), endocyclophotocoagulation and canaloplasty. It is my usual preference to combine trabeculectomy surgery with mitomycin C (0.4 mg/mL for 2 minutes) with the phacoemulsification technique through a single-site superior location. Under local anesthesia (ie, topical, subconjunctival and intracameral), I employ a fornix-based conjunctival flap incision, leaving a 1-mm skirt of tissue that allows for easy closure with a running, intermittent locking stitch of 9-0 monofilament Vicryl suture on a BV (blood vascular) needle. A releasable 10-0 nylon corneal suture is instituted to facilitate ease of early postoperative IOP control.

James C. Tsai, MD, is an OSN Glaucoma Board Member.

Combined surgery no longer has same role it once did

The short answer is yes, there is still a role for combined surgery. However, it is a dramatically altered role as compared with 10 years ago.

Thomas W. Samuelson

It is true: Cataract surgery does lower IOP in most patients, especially those with higher than average preop IOP. Indeed, I believe that we need to reassess the term phacomorphic glaucoma, a term typically reserved to describe forward movement of the lens/iris complex partially blocking access of aqueous to the trabecular meshwork. While this mechanism of glaucoma remains important, a far more common lens-related glaucoma may be “phacomorphic open-angle glaucoma,“ in which the angle recess remains completely open. While much research is needed to better understand the mechanism, it may be that in susceptible patients the enlarging native lens may compress the trabecular meshwork or perhaps cause subtle forward rotation of the scleral spur, resulting in reduced facility of outflow despite an open angle. Cataract surgery may alleviate this lens-related effect, subsequently lowering IOP. Further, there may be chemo-modulators that are activated by the phacoemulsification process itself that may contribute to the pressure-reducing effect of cataract surgery.

While the mechanism involved is speculative at best, the fact that cataract surgery lowers IOP in most patients seems quite solid. The net effect is fewer combined procedures are performed, and appropriately so. Most patients have enough residual nerve tissue and visual field reserve that surgeons can remove the cataract, reassess the new baseline IOP and reinstate medications as needed to control IOP. However, every day I am reminded in clinic that there remain many patients in whom the glaucoma is extremely advanced, rapidly progressive or hopelessly uncontrolled. Such patients can still benefit from the combined procedure. Moreover, as less invasive procedures targeting conventional outflow are developed, safer combined procedures that may be additive to the favorable effect of cataract surgery will keep the combined procedure option viable for our most challenging glaucoma patients.

Thomas W. Samuelson, MD, is the OSN Glaucoma Section Editor.