Comprehensive ophthalmologists take combination approach to treating glaucoma
I am primarily a corneal, cataract and refractive surgeon with an interest in glaucoma associated with cataract and corneal pathology. In our group at Minnesota Eye Consultants, we have four fellowship-trained glaucoma specialists. It is my strong impression that the patients I treat in my clinic are different from those my glaucoma specialist partners treat. In my opinion, there is “comprehensive ophthalmologist glaucoma” and “glaucoma specialist glaucoma,” and they are a different disease. The patients I see are losing vision from cataract or corneal disease and happen to have ocular hypertension or mild to moderate glaucoma, usually well controlled with topical medications. The patients my glaucoma specialist colleagues see are going blind from glaucoma despite maximally tolerated medical therapy and might or might not happen to have an associated cataract or corneal problem. I believe this difference in patient population explains the different perception comprehensive ophthalmologists and glaucoma specialists have regarding microinvasive glaucoma surgery. My comments will be for the surgeon treating “comprehensive ophthalmologist glaucoma.”
First, my favorite and most effective operation for the patient with glaucoma that I treat is clear corneal cataract surgery with implantation of a posterior chamber IOL. The typical patient enrolled in the MIGS studies all had a washout off-medications IOP of 25 mm Hg to 26 mm Hg. With cataract surgery alone, IOP reduction in such a patient is 5 mm Hg to 10 mm Hg. And almost too good to be true, the higher the pre-cataract surgery IOP, the greater the pressure reduction with cataract surgery. Cataract surgery alone is a powerful glaucoma operation and also helps patients see better, generating high patient satisfaction.
The “3G syndrome” is glaucoma, glasses dependence and glare from early cataract. It is a triple win for these patients to undergo a clear cornea phacoemulsification with placement of an IOL at an early stage. While controversial to some, I recommend cataract surgery at an earlier stage in the patient with glaucoma than in the patient without glaucoma, especially if the patient has significant ametropia and presbyopia. I do not hesitate to offer refractive cataract surgery options including toric, extended depth of focus (EDOF) and accommodating IOLs. With ocular hypertension or very mild glaucoma, even a diffractive multifocal is reasonable, although I currently favor EDOF IOLs because glaucoma can decrease contrast sensitivity, sometimes additive to the loss of contrast inherent in a diffractive multifocal. Bottom line, I am more aggressive in recommending cataract surgery in the phakic patient with glaucoma and cataract and am comfortable performing refractive cataract surgery in these patients.
When I am planning cataract surgery on any patient requiring antihypertensive topical medication, especially with evidence of glaucoma damage, I always offer the patient the opportunity to have the cataract surgery combined with MIGS. Every 1 mm Hg reduction in IOP reduces the risk of progressive glaucoma damage 10%, and any reduction in medication burden enhances compliance and patient satisfaction while also reducing cost. I always start with a so-called trabecular bypass device such as the Glaukos iStent. In my opinion, the data support this technology as the safest procedure. I have implanted the Glaukos G3 Supra, which is similar to the Alcon/Transcend CyPass in which fluid is shunted from the anterior chamber into the suprachoroidal space, during a trip to Armenia. I personally found this procedure to be technically easier than the iStent, but the clinical trial data to date confirm a slightly higher complication rate. I am therefore currently reserving suprachoroidal stents for patients in whom cataract surgery, iStent and one to two topical medications do not generate satisfactory IOP reduction.
Today, I never use more than two bottles of antihypertensive medication as we now have three FDA-approved two-drug combinations and a compounded alternative with all three of the topical medications (timolol, dorzolamide and brimonidine) that I would add to my first-line generic latanoprost at bedtime. Studies confirm that compliance, while poor in general, is better when two or fewer bottles of drops are prescribed.
I see the Allergan Xen procedure as being in a different category than an ab interno trabecular bypass or a suprachoroidal stent. To me, Xen is an ab interno microinvasive filtration surgery. It still requires subconjunctival mitomycin C for best outcomes, and postoperative hypotony can occur as can an encapsulated bleb that requires needling or revision. When filtration surgery or a tube shunt is required, I prefer to refer my patients to one of my glaucoma specialist colleagues. However, I am impressed that in my typical patient presenting with cataract and mild to moderate glaucoma, the likelihood of failing to achieve adequate IOP control with a combination of cataract surgery, trabecular bypass, a follow-on suprachoroidal stent and four topical antihypertensives in two bottles is close to zero. I do see patients with severe glaucoma who require filtration surgery or a tube shunt as a primary procedure, and I refer those up front to my glaucoma specialist colleagues. These are patients with “glaucoma specialist glaucoma” who are going blind from glaucoma and in my opinion deserve treatment by a glaucoma specialist.
For my cataract patients who happen to have ocular hypertension or mild to moderate glaucoma, no one managed with cataract surgery, an iStent and topical antihypertensives has required a trabeculectomy or tube shunt in the last 5 years. It is very manageable for the comprehensive ophthalmologist cataract surgeon to develop the skills required to perform a trabecular bypass procedure and a suprachoroidal stent. I do not think today’s cataract surgeon needs to be skilled in trabeculectomy or tube shunt, as they will rarely be required, and procedures performed only a few times a year are hard to perfect. Laser procedures such as selective laser trabeculoplasty and the newly approved MicroPulse (Iridex) are also fairly easily learned and make sense for most comprehensive ophthalmologists.
Of note for the future, there are several other ab externo microinvasive laser surgery procedures in development that have promise to replace ALT and SLT. Along with injected microinvasive drug delivery implants placed in the office or operating room, glaucoma is destined to increasingly become a surgical disease. As I look to the future, most comprehensive ophthalmologists will never again need to perform a trabeculectomy or tube shunt. I, for one, will not miss doing these procedures and managing their many complications. We comprehensive ophthalmologists will be treating our glaucoma patients with a combination of antihypertensive drops, extended-release drug delivery devices such as punctal plugs and conjunctival rings, cataract surgery, MIGS, microinvasive laser surgery, microinvasive drug delivery and maybe pressure-reducing goggles worn at night — the key feature in all of these operations and treatments for we ophthalmic surgeons and our patients being microinvasive.
Disclosure: Lindstrom reports he is a consultant for Glaukos, Alcon, Allergan, J&J Vision, Ocular Therapeutix, Imprimis and Equinox.