As the population ages, the prevalence of both cataracts and glaucoma will continue to increase. Eyecare providers may find that what is already a complex conversation is becoming even more intricate as more surgical treatment options for both conditions become available.
A patient’s first visit to an ophthalmologist may be following the diagnosis of visually significant cataracts, but many already carry the diagnosis of glaucoma from their optometrist. It is increasingly important for smooth integration of medical and surgical care for the growing number of patients with both conditions.
Glaucoma status and IOP
At the time of referral, it is important to include background data on a patients’ glaucoma status including current medications and intolerances as well as intraocular pressure (IOP) trends and any ancillary testing such as visual fields or optical coherence tomography (OCT) studies. Understanding the status and severity of a patient’s condition helps to set the stage for surgical discussion when considering cataract surgery and potential surgical management of glaucoma.
While it is understood that standard phacoemulsification cataract surgery may provide a modest improvement in intraocular pressure,1 recent advances in minimally invasive glaucoma surgery (MIGS) have allowed for more definitive IOP management at an earlier disease stage. A referring doctor may also note whether the patient has any difficulty with adherence or administration of topical treatments, as in either case it may greatly benefit a patient to reduce their eye drop burden.
Pre-surgical evaluation for MIGS
During an evaluation, the surgeon must determine based on the aforementioned data as well as gonioscopic exam whether the patient is a candidate for MIGS at the time of cataract surgery. While certain MIGS procedures are known as “stand-alone” procedures and can be performed independent of cataract surgery, several are approved only in the setting of cataract surgery.
In general, an appropriate candidate for MIGS would have mild to moderate stage glaucoma, desire an alternative to topical drop therapy for IOP management, or have intraocular pressure inadequately controlled by non-surgical treatments such as antihypertensive drops or selective laser trabeculoplasty (SLT).
Due to the relative novelty of these procedures, many patients are not yet aware that there may be a way to reduce or eliminate their dependence on IOP lowering eye drops via surgical intervention. Many of these techniques add only a few minutes to the cataract surgery, an almost imperceptible difference to the patient. MIGS has a more favorable safety profile as compared to traditional incisional glaucoma filtration procedures, with lower risk of complications such as hyphema, hypotony, choroidal effusions, or choroidal hemorrhages.2 Most can also be performed through the existing phaco incisions, and post-operative care is essentially the same as a cataract-only surgery.
As the field of minimally invasive glaucoma surgery has grown, there are various angle-based procedures primarily aimed at increasing outflow through the trabecular meshwork and Schlemm’s canal. A variety of implanted devices and tissue modifying devices are available at the surgeon’s discretion, based on the individual patient’s case. In general, MIGS devices are indicated for patients with diagnosis of ocular hypertension or open angle glaucoma (OAG), typically in the mild to moderate stage, though there are certain MIGS which are approved for use even in severe stage OAG. Some are approved as stand-alone procedures while others are utilized only in conjunction with cataract extraction.
Minimally invasive glaucoma surgeries: assessing the options
Approximately a dozen different MIGS options exist, with surgeon discretion based on patient factors as well as surgical training and experience. One great benefit to such procedures is the facility and availability to a broader range of ophthalmologists, which will help decrease the burden on glaucoma specialists.
Glaucoma is currently estimated to affect over three million Americans, with projections of as many as seven million affected by 2050.3
During consultation for patients with both cataracts and glaucoma, a comprehensive examination as well as review of pertinent history is imperative. The physician must discuss with the patient whether they are a candidate for surgical intervention for one or both diagnoses, and then provide informed consent via discussion of the risks, benefits, and alternatives to any procedures being offered. It may be necessary to have several office visits prior to surgery in order to properly stage a patient’s glaucoma status. This may include updated testing such as perimetry and retinal nerve fiber layer analysis.
If a new diagnosis of glaucoma is made at the time of consultation for cataract surgery, it may be necessary to initiate a trial of intraocular pressure lowering eye drop therapy for a period of several weeks in order to assess for response to treatment.
Candidacy for MIGS with cataract surgery may include patients with difficulty adhering to an eye drop regimen, intolerance to topical medication ingredients or side effects, or difficulty self-administering drops; those for whom medical therapy is not adequately controlling intraocular pressure; or those who simply desire to reduce their dependence on topical treatments.
Most MIGS surgeries are performed under topical or regional anesthesia in the operating room setting. Typical follow up from surgery includes several monitoring visits where the patient is assessed for evidence of continued healing via reduced intraocular inflammation, improving vision, and measurement of intraocular pressure trends. When performed in conjunction with cataract extraction, follow-up intervals are typically no different than those for standard cataract surgery.
Post-operative cataract and glaucoma co-management
Post-operative eye drops are generally the same for cataract surgery with or without MIGS. Surgeon preference may vary regarding continuation of IOP-lowering eye drops during the immediate postoperative period. Some surgeons may prefer to continue IOP-lowering treatment until topical steroid drops are discontinued following surgery. Others may immediately discontinue IOP drops following surgical intervention.
In the event that a patient is on multiple topical therapies prior to surgery, a stepwise approach to reducing the drop regimen may also be implemented, with IOP monitoring at intervals prior to each medication discontinuation.
Co-management of patients with both cataracts and glaucoma is an essential part of their optimized care. Referring doctors may have a role in the long term monitoring of intraocular pressure following surgical intervention, and can observe for continued trends in IOP after surgery.
Many patients are able to reduce or eliminate daily eye drops from their routine following these procedures, though the diagnosis of glaucoma does not disappear –continued monitoring of visual fields and optic nerve health remains necessary over the patient’s lifetime. This is an important point on which to counsel patients, as it is possible that some may have the misconception that their condition is “cured” by the surgeries.
Key points
Understanding the mechanism of action for the various MIGS devices and their effects on the target tissues is imperative for optometrists who are interested in co-managing these patients. Beginning with visits prior to surgical referral, an optometrist may be able to initiate a discussion with the patient about potential treatments for both cataracts and glaucoma, and refer to surgeons who offer these options. Following surgery, the referring optometrist should be aware of potential complications and the usual expectations for post-operative care and recovery.
References
- Berdahl, JP. Cataract Surgery to Lower Intraocular Pressure. Middle East Afr J Ophthalmol. 2009 Jul-Sep; 16(3):119-122.
- Saheb H, Ahmed I. Micro-invasive glaucoma surgery:current perspective and future directions. Current Opinions Ophthalmol. 2012:23(2)96-104.
- Vajaranant TS, Wu S, Torres M, Varma R. A 40-year forecast of the demographic shift in primary open-angle glaucoma in the United States. Invest Ophthalmoly Vis Sci. 2012:53(5), 2464-6.
