A number of factors contribute to the job security of optometrists who manage glaucoma. For one, the current approach to glaucoma treatment (ie, lowering IOP) is indirect and suboptimal. Absent a cure for glaucoma, optometrists will continue to battle this disease every day for the foreseeable future. Additionally, life expectancy in the United States increased in 2019 after several years of decreasing, and it is expected to continue rising.1 Meanwhile, ophthalmology growth numbers are projected to be stagnant. New medications are creating more nonsurgical options for treating glaucoma. And new surgical options for glaucoma are making comanaging patients with the disease easier as the rates and severity of complications decrease. All of these factors suggest that there is a significant role to be played by optometry in the management of glaucoma for some time to come.
As the number of techniques and devices for glaucoma surgery expands dramatically, it is vital to keep yourself educated on the options and what to look for in the short and long term postoperatively. This article covers several key points about comanagement of surgical glaucoma patients, but it is important to communicate with surgeons to whom you make referrals to ascertain their preferred specifications for comanagement.
MICROINVASIVE GLAUCOMA SURGERY
Microinvasive glaucoma surgery (MIGS) is becoming increasingly common as new technologies become available. These procedures are generally indicated for the treatment of mild to moderate glaucoma, and they can reduce the number of medications that a patient requires for IOP control. A major benefit of MIGS procedures is their superior safety profiles compared to more invasive surgical procedures such as trabeculectomy and the implantation of glaucoma drainage devices, which are indicated for more advanced disease.
Schlemm Canal–Based Procedures
The iStent Trabecular Micro-Bypass Stent (Glaukos), iStent inject (Glaukos), and Hydrus Microstent (Ivantis) are FDA approved for implantation only in combination with cataract surgery, so normal postoperative cataract monitoring should be followed. For the first few weeks after surgery with these devices, observe patients’ IOP and symptoms.
At 1 to 2 weeks after surgery, perform gonioscopy to assess the position of the MIGS device and to look for peripheral anterior synechiae. If the device is out of position, notify the surgeon, who may or may not choose to reposition it. It is also important to perform gonioscopy once a year with these devices to monitor for peripheral anterior synechiae.
Roughly 6 to 8 weeks after surgery, after any typical inflammation has resolved and the eye has healed, a new baseline IOP can be determined.
Be sure to communicate with the surgeon about the patient’s postoperative use of glaucoma medications. Some ophthalmologists may prefer to eliminate the medications early on and add them back as necessary, whereas others may prefer to wait to adjust medications until the patient is stabilized after surgery.
Trabecular Meshwork-Based Procedures
These MIGS procedures and devices include ab interno canaloplasty; gonioscopy-assisted transluminal trabeculotomy, or GATT; the Trabectome (MicroSurgical Technology); the Kahook Dual Blade (New World Medical); and the Omni Surgical System (Sight Sciences). Hyphema can be a threat during the early postoperative period. Monitor IOP and the extent of the hyphema just as you would any hyphema. Immobilize and stabilize iris structures with atropine if necessary. Stress to patients the importance of minimizing physical activity; avoiding bending, stooping, and lifting heavy objects; sleeping at an angle of at least 30˚; and wearing a protective eye shield. Ocular hypertensive agents may be used as needed. Some patients may need an extended steroid taper to allow inflammation to clear.
Whether using Micropulse technology (Iridex) or not, cycloablation involves targeting melanin in the ciliary body with a diode laser. The goal is to lower IOP by decreasing the production of aqueous humor.2 Cycloablation is relatively safe, but patients should be monitored for hypotony, inflammation, and uveitis after surgery. Some patients may not respond to laser treatment, in which case further surgical intervention can be considered.
TRADITIONAL FILTRATION SURGERY
When it is time to abandon the natural drainage system of the eye because IOP is uncontrolled and/or glaucoma is progressing, trabeculectomy or a glaucoma drainage device can create a new drain in the eye. These filtering techniques shunt aqueous humor from the anterior chamber to the subconjunctival space.
Early Postoperative Period With Filtration Surgery
Monitor patients for leakage at the incision site. If a Seidel test is positive, apply a bandage contact lens, ensure that the patient is using an antibiotic, and follow up every 1 to 2 days.
To assess the functionality of a trabeculectomy or if IOP is too high, use the lower eyelid to gently massage the lower one-third of the cornea and watch for elevation of the bleb. This technique can help to establish the bleb and lower IOP. If this strategy is not effective, use a cotton-tipped applicator soaked in proparacaine to gently massage the conjunctiva/sclera adjacent to the scleral flap. Doing so will open the flap and elevate the bleb. Massage is most efficient 7 to 10 days after surgery. After 2 weeks, if the IOP is still too high, the surgeon can perform suture lysis to open the scleral flap further. Cutting the sutures earlier than this increases the risk of hypotony. Resist the urge to restart glaucoma medications—especially aqueous suppressants—too quickly.
For patients who have received a glaucoma drainage device, evaluate conjunctival coverage over the tube and the plate. Exposure can cause the patient to feel discomfort or pain and increases risk of endophthalmitis. In this situation, ensure that the patient is using antibiotics and make a referral for surgical revision.
The Xen Gel Stent (Allergan) is a recent addition to the surgical armamentarium. This device, originally placed ab interno but now placed ab externo, can be a safer procedure than a trabeculectomy, as less manipulation of the eye is needed during surgery. The efficacy of IOP reduction with the Xen Gel Stent has been found to be similar to that obtained with trabeculectomy.3 Aqueous fluid is still shunted subconjunctivally, as with a trabeculectomy, so similar precautions apply. Instead of suture lysis for early postoperative IOP elevation, bleb needling by the surgeon is often indicated.
Monitor patients for exposure of the tube or plate of a glaucoma drainage device over time and for infection of the bleb (blebitis). Patients with blebitis will likely experience symptoms such as epiphora, pain, mucous discharge, and conjunctival redness. Evaluate patients for anterior chamber and vitreous cells. Examine the bleb for surrounding conjunctival injection and for purulence and hypopyon in the bleb. Look carefully for a bleb leak.
Treat blebitis aggressively with antibiotics (ie, a fourth-generation fluoroquinolone administered hourly) and follow up daily. If there are any concerns about endophthalmitis, refer the patient back to the surgeon or to a retina specialist.
What If IOP Drops Too Low After Surgery?
MIGS procedures based in Schlemm canal or the trabecular meshwork carry little to no risk of hypotony unless there is a wound leak. This is because the shunted aqueous fluid still must feed into the episcleral veins, which have a backstop pressure of 8 mm Hg to 10 mm Hg.4
Early hypotony can occur after trabeculectomy or placement of a glaucoma drainage device, so patients generally discontinue using glaucoma medications immediately after surgery. One exception to this timeline occurs with use of a Baerveldt glaucoma implant (Johnson & Johnson Vision), which does not fully open until about 6 weeks postoperatively. Patients implanted with these devices may continue taking glaucoma medications until around 6 weeks after surgery. If hypotony occurs, grade the anterior chamber depth. Any shallowing should raise concern, with the seriousness increasing from peripheral iris-cornea touch to iris-lens touch.
Mild hypotony changes can be managed with twice-daily dosing of atropine to help rotate the ciliary body posteriorly and deepen the anterior chamber. Tapering topical steroids can also be helpful because it allows the conjunctival bleb to scar and limits the size of the bleb reservoir. In most instances of hypotony, however, urgent involvement of the surgeon or surgeon group is warranted because manual deepening of the anterior chamber may be advisable (usually with intracameral injections of an ophthalmic viscosurgical device).
Monitor patients for choroidal detachment. Stress to them the importance of activity restrictions (avoidance of straining, bending, and lifting) to prevent further choroidal involvement and suprachoroidal hemorrhage.
COMANAGEMENT: A WIN-WIN-WIN SITUATION
It is important to have a firm understanding of both medical and surgical management of glaucoma and to develop a strong relationship with a glaucoma surgeon for patients who need advanced care. Comanaging surgical glaucoma patients can be helpful to the surgeon, rewarding for you, and, most important, beneficial for the patient.
The best way to comanage glaucoma is to develop a professional relationship with a glaucoma surgeon or surgeon group. When medication—and selective laser trabeculoplasty in states where optometrists may perform the procedure—is not adequately controlling the disease, it is important to refer the patient for tertiary glaucoma care in a timely fashion. Unfortunately, some optometrists postpone making a referral for fear of losing the patient to an ophthalmologist’s practice. With clear communication, this does not have to be the case.
Make the surgeon aware of your comfort level in managing glaucoma patients, including postoperative care. It can be rewarding to care for patients together as part of a trusting relationship.
1. U.S. Life Expectancy 1950-2020. Macrotrends. www.macrotrends.net/countries/USA/united-states/life-expectancy. Accessed February 28, 2020.
2. Kuchar S, Moster MR, Reamer CB, Waisbourd M. Treatment outcomes of micropulse transscleral cyclophotocoagulation in advanced glaucoma. Lasers Med Sci. 2016;31(2):393-396.
3. Gregorio ADe, Pedrotti E, Stevan G, et al. Xen glaucoma treatment system in the management of refractory glaucomas: a short review on trial data and potential role in clinical practice. Clin Ophthamol. 2018;12:773-782.
4. Schweitzer J. How to comanage MIGS patients. Optometry Times. 2019;11(1):21-25.