Cataract Surgery Report

Caught in the middle: glaucoma and cataract

A stepped surgical approach could be the answer.

By E. Randy Craven, MD, FACS and Saud A Juhani, MD

	About the Authors: Col. Saud Abdulaziz al Juhani, MD, is a fellow in glaucoma at King Khaled Eye Specialist Hospital, Riyadh, saudi Arabia.
	E. Randy Craven, MD, is chief of glaucoma at King Khaled eye specialist Hospital. He was the first US surgeon to implant the iStent, in the FDA trial, and the CyPass. Disclosure: Dr. Craven is a consutant to Glaukos and Transcend Medical.

Not too many years ago, we avoided cataract surgery in patients with glaucoma because of the fears about raising IOP or about damaging the conjunctiva. Now we see interest in removing cataracts to help reduce IOP in patients with co-existing glaucoma. The thought that doing a cataract surgery would help glaucoma is of interest to a lot of us because patients like cataract surgery. The patient accepting glaucoma surgery options, on the other hand, is more of a struggle. She or he has fears. So we balance the need for IOP reduction with keeping patients happy and seeing the way they want. The prior age of glaucoma surgeries made it difficult to be of a “refractive” mentality at times. Happily, that is less difficult now. Let’s look at today’s cataract options for glaucoma patients.

OF MIGS AND PHACO

Trabeculectomy or other full-thickness options are fraught with bleb-related concerns and issues. Thus, we have seen a surge in “non-penetrating procedures” such as canaloplasty, and great interest in micro-stents (MIGS). The MIGS procedures have had considerable press recently.¹ Micro-stents work by either increasing the trabecular outflow (iStent, Glaukos, Laguna Hills, Calif.) or increasing uveoscleral outflow into the suprachoroidal space (iStent Supra and CyPass) (Figure 1). Just a year ago, we saw the first approved MIGS. Since the release of the iStent, many comprehensive surgeons are dipping a toe in the glaucoma surgical waters.

Figure 1. MIGS Procedure: the CyPass. Here you can see the stent into the angle separating the iris root from the ciliary body. This MIGS device recently completed surgical enrollment for the US FDA trial.

With good reason. We all want a happy patient; at least with the MIGS, we are not harming the patient. Now we eagerly await the data indicating if multiple stents will let us get better IOP control. MIGS intrigue is reinforced by avoiding wound-healing issues we see with incisional surgery. That has been a huge hang-up for many comprehensive surgeons. The idea of needing to nurse along a trabeculectomy until it is working causes some trepidation, but the unpredictable blebs are even more of a concern. The other draw to MIGS is looking for a physiologic outflow and not a hole. If we can boost the trabecular flow or increase uveoscleral outflow, that sounds much better than making a hole.

Phacoemulsification alone might be considered a benefit to glaucoma patients, both open- and narrow-angle. Poley and co-investigators found that phaco alone had a significant effect on IOP, especially in patients with an IOP in the 20s.² The other advantage that cataract surgery alone (and now cataract with MIGS) offers is a more precise refractive outcome.

Most patients now expect to see better from surgery, not worse, so a procedure that improves rather than detracts from the refractive outcome is worth considering. Many refractive and cataract surgeons like the idea of a toric or multifocal IOL for patients without much field loss — even more reason to consider phaco alone, if you feel it is safe for the patient.

MATCHING THE OPTION TO THE PATIENT

Really, the decision to do a glaucoma procedure in conjunction with cataract surgery rests on your evaluation of the optic nerve and visual field damage. For patients who have mild glaucoma, perhaps a less invasive procedure is best, such as phaco alone or phaco and MIGS. Keep in mind that most of the FDA studies evaluating MIGS implants look at patients with mild visual field loss, not patients requiring large IOP reductions.

Patients with advanced glaucoma may need more aggressive surgery. Many surgeons are considering a stepped approach using the MIGS procedures or phaco as step one, with additional procedures if necessary. Take the cataract and glaucoma patient with an early nasal step, some cupping and a pressure slightly high on two medications. You might consider an iStent with the cataract surgery first. If the IOP is up, check if the additive effects of the medications are enhanced since the surgery. Maybe with the iStent, phaco and a medication, you get the same IOP as if you did a trabeculectomy. If not, then maybe consider a canaloplasty or trabeculectomy next; at least you gave it a shot to avoid a bleb.

Sometimes, however, it is best to go with a more traditional surgery. If you have a patient with split-fixation and you believe the patient could not tolerate an IOP spike (which can happen after phaco or iStent), then the choice of a trabeculectomy or more standard filtration surgery is probably the best one.

Patients with angle-closure might achieve a more open angle with the lens coming out. The additional benefit is you have better access to procedures that can open the angle, such as endoscopic cyclophotocoagulation (ECP). ECP used on the anterior ciliary processes shrinks the tissue and opens up the angle. Early angle-closure may be helped by a goniosynechialysis as well. OCT really help you see the angle crowing coming from the lens (Figure 2).

Figure 2. Angle closure. The lens shows significant vault with a thick iris pushed forward. Removal of the lens is a consideration for patients with cataracts.

VENTURING INTO NEW TERRITORY

Given the patient with mild glaucoma is the one most likely to be a candidate for a MIGS procedure, how and when do you adopt a new technique? The surgeon looks for the best fit for him and the patient when choosing a new surgical procedure. Usually we are most comfortable modifying an old technique and using the modification as a new option. Sometimes learning a completely new procedure, such as MIGS, helps us reach a new goal.

You can slowly venture into the MIGS arena by using the goniolens at the beginning or at the end of the cataract surgery. First, tilt the head and microscope and then view the angle with the surgical goniolens. Some surgeons use the viscoelastic cannula to traverse the anterior chamber and reach the opposite angle to get used to the “feel” of MIGS.

THE ECP OUTLOOK

ECP has been used successfully by some surgeons for glaucoma patients undergoing cataract surgery. In Brazil, investigators compared ECP with the Ahmed valve in a group of patients with more advanced glaucoma than we might consider for MIGS.³ They found no difference between ECP and Ahmed valves.

Our experience in Saudi Arabia is that the ECP works very well when combined with cataract surgery. The experiences in the United States, however, have not been as encouraging. Because literature on ECP is quite limited, making an evidence-based choice is difficult. Regardless, the ECP seems to offer an option for the patient undergoing cataract surgery; if the surgeons embrace the technology good results appear possible.

WHEN YOU NEED MORE

If you are interested in further IOP reduction for your patient, a trabeculectomy, canaloplasty or a tube may be an option. Canaloplasty appears to do well with cataract.⁴ The Tube vs Trabeculectomy study (TVT) speculated that some of the success with the tubes was the change from our prior incision techniques to clear-cornea; some have theorized that doing a combined tube and cataract might be an option if you need significant IOP reduction.⁵ The challenge with these larger-incision procedures is that of the wound healing, chamber stability, hypotony and other similar problems.

Using a refractive IOL in patients undergoing a trabeculectomy is tricky due to the astigmatism from sutures in the scleral flap or the conjunctiva. Some surgeons have moved toward a smaller, more “refractive” trabeculectomy with better predictability on the astigmatism. A trend in Europe and the United States involves surgeons using the non-penetrating procedures (canaloplasty and deep sclerectomy) without securing the scleral flap to try to decrease induced astigmatism and to allow for the possibility of a toric IOL and more astigmatic predictability.

NEW POSSIBILITIES, BETTER VISION

In 2013, we are at the threshold of new and better options for our glaucoma patients with a co-existing cataract. Clinical trials have begun to look at what works best for our patients with these two conditions. Possibly we will learn that a step-like sequence is best, where we consider phaco alone, phaco with ECP or MIGS, and then, if necessary, the more aggressive step of phaco plus incisional surgery.

Guiding our decision as to which procedures to use will factor in the disease level, evidence from studies and the surgeon’s own experience. Ultimately, however, the patient’s demand for acceptable visual recovery as well as tolerability for problems will drive a lot of the decisions. OM

References

1. Craven ER, Katz LJ, Wells JM, Giamporcaro JE, iStent Study G. Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: two-year follow-up. J Cataract Refract Surg. 2012;38:1339-1345.

2. Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes. J Cataract Refract Surg. 2008;34:735-742.

3. Lima FE, Magacho L, Carvalho DM, Susanna RJ, Ávila MP. A Prospective, Comparative Study between Endoscopic Cyclophotocoagulation and the Ahmed Drainage Implant in Refractory Glaucoma. Journal of glaucoma. 2004;13:233-237.

4. Lewis RA, von Wolff K, Tetz M, Koerber N, Kearney JR, Shingleton BJ, et al. Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg. 2011;37:682-690.

5. Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL, et al. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. AJO. 2012;153:789-803 e2.