As a Cataract, Cornea and Refractive Surgeon, it would seem odd that the topic I’ve chose to discuss in this newsletter is glaucoma surgery. This is, perhaps, the point – glaucoma surgery is no longer strictly the burden of a glaucoma specialist. Glaucoma surgery has become mainstream over the past few years and finds itself in the wheelhouse of your friendly neighborhood anterior segment surgeon – but I am not talking about traditional ‘tubes and trabs’. Specifically, a range of procedures that fall under the umbrella called ‘MIGS’ (MicroInvasive or Minimally Invasive Glaucoma Surgery) has exploded since 2012 and is now performed routinely by our surgeons.
The concept of MIGS was born out of some basic needs of glaucoma patients that weren’t being met very effectively. Traditional glaucoma surgery was mostly reserved for cases where maximal medical therapy was no longer effective or the glaucoma was too severe and advanced for medication management. This left a significant proportion of patients with mild or moderate open angle glaucoma with only medication as an option. Notably, 75% of glaucoma patients take one or two drops. As a Corneal specialist, I am intimately familiar with the chronic effects of topical glaucoma medications. In fact, for this reason as well as for patient compliance and cost concerns, I have long incorporated SLT in my practice – often first-line. As a Cataract surgeon, I recognize the opportunity that being in the anterior chamber provides a valuable opportunity to intervene micro-invasively for my mild to moderate glaucoma patients. This is where MIGS comes into my practice – specifically the iStent and ECP.
MIGS is evolving rapidly and many of you may be familiar with a few of the procedures that qualify as ‘MIGS’. The salient features of MIGS procedures when compared with traditional glaucoma procedures are:
⦁ Indicated for primary open angle glaucoma, pseudoexfoliation glaucoma, or pigmentary dispersion glaucoma
⦁ Better safety profile
⦁ Less invasive
⦁ Shorter surgery time
⦁ Rapid recovery
⦁ Generally combined with cataract surgery
⦁ Reduces dependence on topical IOP lowering agents
Here is a brief list of MIGS procedures available today or soon to be available in the near future:
⦁ iStent (Glaukos)
⦁ Endocyclophotocoagulation (ECP)
In Clinical Trials
⦁ Hydrus Microstent (Ivantis)
⦁ Cypass Microstent (Transcend Medical)
⦁ AqueSys XEN (AqueSys)
⦁ InnFocus MicroShunt (InnFocus)
⦁ iStent Supra (Glaukos)
The existing procedures are generally accepted to be safer and more efficient. Though short term data looks promising, the efficacy of these procedure still lacks long term data. Moreover, studies comparing MIGS to traditional glaucoma surgery or MIGS procedures to each other are lacking. Though long term data is lacking, short term observations suggest significant IOP reduction in most cases with months or years of delay/reduction in usage of IOP lowering topical medication. Should you co-manage cases as these, it should be noted that the effect of IOP lowering can take several weeks to materialize during which time I recommend continuing the pre-existing IOP lowering medication(s). The medication can be tapered under a watchful eye after cessation of the post-cataract surgery steroid regimen so as to avoid an IOP spike.
Notably, there are some contraindications to be aware of for MIGS procedures:
⦁ Very low IOP requirement
⦁ Neovascular glaucoma
⦁ Angle or anterior chamber abnormalities
⦁ Advanced glaucomatous damage
⦁ Previous trabeculectomy or tube implantation
In summary, the age old disease of glaucoma has a new and evolving foe called MIGS. You are likely to see more and more of your cataract patients who also have open angle glaucoma being managed with one of the aforementioned, advanced techniques by a cataract surgeon. Co-managing these patients effectively is uncomplicated and can be discussed with your surgeon partner.
The surgeons at Milan Eye Center look forward to surgically managing your cataract and glaucoma patients.