A Comprehensive Approach to Surgical Glaucoma Therapy
Dr. Nathan M. Radcliffe
When considering glaucoma medical therapy, many of the agents we use treat glaucoma lower intraocular pressure by decreasing the amount of aqueous humor that is produced. Of course, our first-line agents are typically the prostaglandin analog class, and those agents increase outflow through the uveal scleral pathway.
We are fortunate today to have a multitude of options for the treatment of glaucoma surgically, but the overwhelming majority of surgical options increase the outflow of aqueous humor. There are however many potential advantages of decreasing the production of aqueous humor, typically achieved through ab interno or ab externo cyclophotocoagulation. Endoscopic cyclophotocoagulation (ECP) is an ab interno (rather than transscleral) approach for cycloablation that utilizes endoscopy with an 810-nm diode laser (Endo Optiks, Little Silver, NJ). Cyclophotocoagulation refers to the thermal targeting of ciliary body pigment epithelial cells to reduce the amount of aqueous humor produced. What makes cyclophotocoagulation unique is that it is one of the few glaucoma procedures that can be repeated and titrated without leaving any conjunctival scars, nor does it alter the outflow pathway anatomy in any way that would preclude any future glaucoma surgical options. Ab interno cyclophotocoagulation is ideally performed in pseudophakic eyes. On the other side of things, in eyes that have significant conjunctival scarring or even severe corneal disease, there are no previous procedures that would prevent one from being able to offer cyclophotocoagulation.
Gayton and colleagues prospectively randomized 58 eyes/patients phacotrabeculectomy versus phaco/ECP.1 They found that 30% of ECP treated patients achieved IOP below 19 mm Hg without medication and 65% achieved IOP below 19 mm Hg with medication, as opposed to 40% and 52% in the trabeculectomy group, respectively. Kahook and colleagues followed 25 patients with a baseline IOP of 24.5 mm Hg after ECP, and at 6 months of follow up, the IOP was 16.0 mm Hg (a 35% reduction), with reduced medication usage from 2.5 to 1.9 medications.
Having adopted endoscopic cyclophotocoagulation several years ago, I've been pleased with the results. I typically combine the procedure with cataract extraction in patients using one or more glaucoma medications (depending on the level of pressure control) whose disease severity does not quite justify a filtration procedure. The two potential issues to manage with the procedure include inflammation and early intraocular pressure elevations. I have adopted a regimen of subconjunctival dexamethasone and oral acetazolamide immediately following the procedure to limit these potential problems, and have been successful in doing so. While hypotony is possible following any glaucoma surgery, it is certainly very rare after endoscopic cyclophotocoagulation. Because the procedure does not utilize an expensive implant, I have been able to offer endoscopic cyclophotocoagulation to patients when other, sometimes newer, implant-based procedures were not covered by insurance. Additionally, in patients with borderline IOP control, on several medications, with moderate glaucoma, the procedure can be considered in addition to an outflow procedure (such as the iStent [Glaukos] or Trabectome [Neomedix]).
In summary, glaucoma can be surgically treated by both increasing outflow and reducing inflow (aqueous humor production). While we have always been comfortable with this dual approach pharmacologically, perhaps it is time we routinely target these options surgically.
1. Gayton JL, Van Der Karr M, Sanders V. Combined cataract and glaucoma surgery: trabeculectomy versus endoscopic laser cycloablation. J Cataract Refract Surg. 1999;25:1214-9.
2. Kahook MY, Lathrop KL, Noecker RJ.One-site versus two-site endoscopic cyclophotocoagulation. J Glaucoma. 2007;16:527-30.
Dr. Nathan M. Radcliffe is the director of the glaucoma service and a clinical assistant professor at
New York Univeristy Langone Ophthalmology Associates and is a cataract and glaucoma surgeon at
the New York Eye Surgery Center.