Triple procedure puts IOP on 'ICE'

Take-home

An ophthalmologist explains how he and some colleagues have had excellent success with a new combination procedure ICE: iStent, Cataract, and Endocyclophotocoagulation.

Dr. RadcliffeBy Nathan Radcliffe, MD; Special to Ophthalmology Times

New York-The past several years have brought an influx of glaucoma treatments: combination mediations, laser therapies, and various surgical options. Of particular note has been the development of microinvasive glaucoma surgery category with its ultra-safe risk profiles.

With the increase in low-risk options, it is inevitable that surgeons begin to investigate combinations of procedures to maximize pressure decreases while maintaining an excellent safety profile.

Some of my colleagues and I have had excellent success with a new combination procedure ICE: iStent, Cataract, and Endocyclophotocoagulation (ECP).

The causes of glaucoma are not entirely understood, but its most common manifestation is the buildup of aqueous humor in the eye, causing an increase of IOP that compresses and damages the optic nerve endings. Most glaucoma treatments are aimed at either decreasing the production of or improving the outflow of aqueous.

Although the mechanism of action is not yet elucidated, published literature demonstrates that phacoemulsification has a modest and sustained positive impact on IOP.¹

The iStent Trabecular Micro Bypass (Glaukos) has been found to create a positive synergy with cataract surgery, further reducing IOP while maintaining the same excellent safety profile.

The 1-mm long iStent is inserted into the trabecular meshwork, creating a patent bypass between the anterior chamber and Schlemm canal to address the issue of resistance to aqueous outflow. In randomized trials comparing iStent plus cataract surgery with cataract surgery alone, pressure reduction on fewer medication was clinically and statistically significantly better in patients who received the combined procedure versus those that received cataract surgery alone.²

In addition, the overall safety profile was similar to cataract surgery alone.

ECP addresses IOP from the opposite angle, by lowering the production of aqueous via ablation of the ciliary processes. Similar to the iStent, a review of 808 patients who underwent either phacoemulsification alone or phacoemulsification combined with ECP showed greater benefit in the combined group with no increased risk of complications.³

A comparison of ECP performed through one incision versus two incisions in conjunction with cataract surgery shows that treatment of the entire 360° of ciliary processes provides better long-term control of IOP and less dependence on topical glaucoma medications.⁴

The existence of complimentary small-incision surgeries that address both inflow and outflow of aqueous seemed an intuitive combination, and my colleagues and I began fine tuning the details of the procedure. We found it most reasonable to begin with phacoemulsification followed by placement of the IOL.

While the iStent could be placed before or after ECP, it makes the most sense to place the iStent directly following IOL placement while the viscoelastic is still in the eye, the angle is deep, and the view through the cornea has not been compromised by the manipulation required during ECP.

In general, I find that a small amount of additional viscoelastic helps to inflate the iridociliary sulcus to perform ECP.

While iStent placement is generally done while visualizing the anterior chamber via gonioscopy, it is also possible to place it with the view provided by the endoscope.

The advantages of this approach include ability to treat patients that are not adaptable to the gonioscope, the greater availability and increased comfort level with a gonioscopy, and saving time by not having to adjust the microscope.

I first performed endoscopic iStent placement when my operating room told me prior to a series of ICE procedures that I had only three gonioscopic lenses, not enough for my four cases. I felt confident that I could place the stent endoscopically and successfully proceeded with the procedure on the first case.

The endoscopic approach works best if you hold the endoscope in your left hand and place a left-handed stent into the angle with your right hand. Both instruments are placed though the 2.75mm temporal clear corneal incision, with the endoscope inserted first.

If a right-handed stent is placed using the right hand, the scope will only provide a view of the back of the iStent inserter and placement, while not impossible, will be less facile. The implantation is very straightforward and withdrawing the endoscope slightly allows a nice broad view while not letting it interfere with stent placement.

The presence of two instruments in the anterior chamber through the corneal main incision at one time can make it difficult to stabilize the eye. On occasion, I have asked an assistant to stabilize the globe in the primary position so that manipulation of the instruments does not alter the position of the eye.

After I have placed the iStent, I gently tug backwards on the inserter and watch to see that Schlemm canal and the internal eye wall are drawn inwards, indicating placement within the canal. After releasing the stent, I tap the device with the inserter to ensure it is well docked and visually check for blood reflux coming from the stent’s heel.

After the iStent is in place, I withdraw the inserter and place a viscoelastic cannula into the sulcus. Looking through either the operating microscope or the endoscope, I watch to ensure that the posterior chamber has been adequately inflated to allow visualization. When that is achieved, the viscoelastic cannula is removed and a standard one site, 270° ECP is performed using the curved 20-g probe.

Patient profile

An ideal patient for this combined procedure was a 72-year-old male who had cataract extraction with ECP 3 years prior, before iStent was available.

His baseline IOP was 21 mm Hg, which was reduced to 16 mm Hg following the procedure. Preoperative, he was taking 3 glaucoma medications and he remained on 2 medications for the following 3 years.

His other eye has now developed cataract alongside moderate glaucoma (IOP of 22 mm Hg) and I felt that we could combine the benefit he received previously from cataract extraction and ECP with that of the iStent, while maintaining and excellent safety profile.

On the second eye, I performed the ICE procedure and 3 months following treatment, his IOP is now 16 mm Hg and he is on 1 medication.

Some of my cases have been more successful than this, and others have not and have moved on to other incisional glaucoma surgeries.

Though we are still evaluating clinical data, early results indicate additional IOP lowering benefit alongside a preserved favorable safety profile.

In more than 50 cases, my colleague, Parag Parekh, MD, of the Laurel Eye Clinic, and I have found none of the typical complications associated with filtration surgery and no incidences of hypotony.

Combined ICE procedures make sense for a variety of reasons. When you consider adding ECP to a planned cataract-iStent procedure, there is no additional implanted material, no increase to facility cost and only a modest increase to operating time

Additionally, the use of the endoscope in place of the gonioscope may provide surgeons a new approach that may expand the number of patients and situations when an iStent can be provided.

References

1.     Augustinu CJ, Zeyen T. The effect of phacoemulsification and combined phace/glaucoma procedures on the intraocular pressure in open-angle glaucoma. A review of the literature. Bull Soc Belge Ophtalmol. 2012;320:51-66.

2.     Samuelson TW, et al. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011;118:459-467.

3.     Berke SJ, Sturm RT, Caronia RM, Nelson DB, D'Aversa G, Freedman M. Phacoemulsification combined with endoscopic cyclophotocoagulation (ECP) in the management of cataract and medically controlled glaucoma: A large, long term study American Glaucoma Society 16th Annual Meeting. Charleston, SC; 2006. Mar 2-5, 2006 Abstract 22:47.

4.     Kahook MY, Lathrop KL, Noecker RJ. One-site versus two-site endoscopic cyclophotocoagulation. J Glaucoma. 2007;16:527-530.

Nathan Radcliffe, MD, is an assistant professor of ophthalmology at Weill Cornell Medical College and the assistant attending ophthalmologist at New York-Presbyterian Hospital. Dr. Radcliffe is a dedicated researcher and teacher and specializes in Glaucoma. Readers may reach Dr. Radcliffe at drradcliffe@gmail.com. He did not indicate any proprietary interest in the subject matter.

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