Managing Postoperative Glaucoma Complications

As the number of individuals with glaucoma continues to rise,¹ we as optometrists are likely to encounter numerous patients with the disease every day, each of whom might require a somewhat different treatment regimen. There is a growing number of treatment options available, but this article focuses only on surgical solutions and, more specifically, on their associated complications.

Due to a number of factors, including compliance and cost, there has been a large shift towards laser and even microinvasive glaucoma surgery (MIGS) as a first-line treatment option for patients with glaucoma.² As with topical glaucoma treatment options, complications are possible with laser and MIGS, so although it’s important to know the benefits of these procedures, it’s equally essential to understand the risks of each.^3,4

BEWARE OF INFLAMMATION AND IOP

Although MIGS is an effective way to manage patients with glaucoma, there can be complications, which are often temporary.³ At times, the complication may be easily identified prior to even examining the eye, based on a patient’s vision and/or IOP. However, to further assess, one should be comfortable using a gonio lens to manage these complications. Common issues that can arise include peripheral anterior synechiae (PAS), blood reflux, IOP spikes, inflammation, and blockage or scarring of a stent.⁵

The most common complications that tend to arise with laser procedures and MIGS are uncontrolled IOP and inflammation. In some instances, patients may be on a short course of an antiinflammatory medication, such as a nonsteroidal antiinflammatory drug (NSAID) or steroid, to prevent inflammation. For patients with a history of iritis, one may consider a longer course of the antiinflammatory. Depending on the surgeon’s preference, patients are typically on antiinflammatories for MIGS.

At our clinic, patients use a combination drop that consists of an antibiotic, steroid, and NSAID for 2 to 4 weeks following their surgery. This drop can be continued or switched to individual antiinflammatory medication if there is persistent inflammation. Some surgeons may prefer that the antiinflammatory medication be tapered over the postoperative period. It is important to evaluate the anterior chamber at each postoperative visit. Rarely, persistent inflammation will lead to cystoid macular edema, which may require further intervention, such as an intraocular steroid injection. However, when treating inflammation with steroids, we should be cautious about an IOP rise or fluctuations.

In most situations, when a patient’s IOP is uncontrolled, the IOP spike is due to healing, such as inflammation, hyphema, or blockage of a stent (from iris tissue or fibrin). Following a laser or MIGS procedure, it may be beneficial to continue a patient’s IOP medications (keep them on aqueous suppressants, but can stop prostaglandin analog right away) until their IOP has stabilized, as IOP can fluctuate during this period and potentially lead to glaucoma progression if left untreated. Once the eye has healed, the patient is off topical steroids, and the IOP has stabilized in the target range, we can slowly start to taper the topical glaucoma treatment. Even after multiple attempts with laser, MIGS, and/or topical treatment, the IOP may still remain uncontrolled and require further surgical intervention. This could be due to the resistance to outflow, which may be beyond the trabecular meshwork and canal and reside in the episcleral venous system.

TRABECULAR MESHWORK AND SCHLEMM CANAL MIGS

When performing gonioscopy, PAS may be present in the area where the goniotomy or stent was placed. PAS is more commonly seen in patients with a history of uveitis/chronic inflammation, trauma, angle closure, or with a history of PAS.⁶ If PAS is seen during the postoperative period, the patient should be started on pilocarpine. In some cases, the surgeon may prefer to prophylactically use pilocarpine in patients who may be more susceptible to PAS postoperatively.

Hyphemas and reflux bleeding are the most common complications.⁷ This complication often occurs early in the postoperative period and, sometimes, the reflux of blood can be viewed upon slit-lamp examination, where there may be a small formed hyphema or rotating red blood cells in the anterior chamber. However, there are times when the reflux bleeding can only be viewed on gonioscopy, so it is important to continue to perform gonioscopy at each follow-up visit for comprehensive monitoring. The blood can also migrate during surgery around the zonules and reside behind the lens, which can cause decreased vision despite the anterior segment being clear of a hyphema.

Typically, the best management is time. Patients should continue taking their antiinflammatory medications, but do not need to increase them because the blood is reflux, not active hemorrhaging. These patients need to be educated to avoid bending over, keep their head elevated at a 45˚ angle, and avoid strenuous exercise until the blood has resolved. There may be a temporary elevation in IOP, so patients should continue their IOP medications, or they may need an additional medication to temporarily control their IOP until it has stabilized. In very rare cases, patients may need an anterior chamber washout, especially in chronic cases or when IOP remains uncontrolled on maximal medical therapy.

There are multiple options when it comes to selecting MIGS for patients. Some commonly used goniotomies include the Kahook Dual Blade (KDB; New World Medical), Streamline Surgical System (New World Medical), TrabEx (MicroSurgical Technology), Omni Surgical System (Sight Sciences), and the iTrack Surgical System (Nova Eye Medical).

iStent inject W (Glaukos), iStent infinite (Glaukos), and Hydrus Microstent (Alcon) are two commonly used stents that bypass the trabecular meshwork and increase aqueous outflow through Schlemm canal. Again, it is important to use gonioscopy to visualize the placement of these stents, as they may be obstructed because of PAS formation or mispositioning. In rare circumstances, the stent may become completely displaced and lead to corneal decompensation. Patients should be referred back to the surgeon for possible Nd:YAG laser (if blocked by the iris) or removal of the stent (if causing inflammation or corneal decompensation).

SUBCONJUNCTIVAL SPACE MIGS

The Xen Gel Stent (Allergan/AbbVie) consists of a 6-mm porcine-device tube that creates a subconjunctival bleb. This MIGS can be very successful in managing IOP, especially for those with moderate to severe glaucoma; however, the risk of complications is higher than conventional outflow MIGS.

Typically, all topical IOP treatment is discontinued on postoperative day 1. Some complications associated with topical IOP treatment include hypotony, conjunctival wound leak, scarring, stent exposure or obstruction, hyphema, or choroidal effusions. When evaluating patients with the Xen Gel Stent, assess for a wound leak. If a leak is found without hypotony, management can consist of the use of antibiotics, aqueous suppressants, and ointment. Bandage contact lenses can also be useful to tamponade the leak. If conservative management is unsuccessful or there is stent exposure, surgical intervention is warranted. Hypotony may be present even without the presence of a wound leak. To prevent the risk of hypotony, all topical IOP treatment should be discontinued postoperatively. To address the hypotony, one should add atropine to keep the anterior chamber formed and to maintain or decrease the steroid to allow conjunctival healing.

Further evaluation should be performed to rule out hypotony, maculopathy, and serous choroidal detachments. Many times, serous choroidal detachments will resolve as IOP increases; however, there may be certain situations in which the detachments may need to be drained if chronic and vision-threatening. If choroidals are significant (near touching), increase steroids to prevent fibrosis. When evaluating the anterior chamber, ensure that the Xen stent is not obstructed. If noted, the patient should return to the surgeon.

One of the most common complications of subconjunctival (space) is fibrosis of the bleb. On examination, this may be difficult to identify; however, if the bleb appears flat or the IOP is elevated, consider interstitial fibrosis. Digital pressure can be performed by applying superior pressure with your fingertip along the lower lid to promote aqueous flow through the Xen, oftentimes leading to a decrease in IOP, which is also a good test for the function of the bleb. Having patients perform digital pressure during the postoperative period can lead to successful outcomes with Xen.⁸ However, if the IOP remains uncontrolled, the patient should return to the surgeon for possible bleb needling, revision, or an antifibrinolytic injection. With a higher risk of complications associated with the Xen stent, it is important to keep an open line of communication with the patient’s surgeon.

PREPARE FOR THE BEST, BUT EXPECT THE WORST

Our patients have an incredible amount of glaucoma treatment options available to them today. In order to be successful in managing any postoperative complications, I keep the following tips in mind, even if I’m not comanaging a patient initially:

• Get to know the patient’s surgeon and be communicative with them
• Take the opportunity to shadow surgeries
• Track your patient’s results from these procedures.

Although most complications you encounter will be temporary and resolve with time, it is still essential to properly diagnose and manage them when they do occur. As the prevalence of glaucoma increases and MIGS procedures continue to evolve, we need to be able to tackle both the positive outcomes and the complications of these procedures.