Surgery for Patients with Symptomatic Cataract and Ocular Hypertension
Glaucoma experts debate phacoemulsification alone versus adding MIGS.
The availability of an array of minimally invasive glaucoma surgery (MIGS) procedures raises the question of whether surgeons should add one of these modalities when performing phacoemulsification for a patient with symptomatic cataract and ocular hypertension (OHT).
In a pro/con discussion, Andrew J Tatham MD spoke in favour of phacoemulsification alone, while Simonetta Morselli MD argued for adding MIGS to standard phaco surgery.
Opening the session, Dr Tatham named six reasons surgeons should perform phacoemulsification alone. He explained the risk for progression to glaucoma is low for most patients, and IOP lowering may not be needed. If it is, it may be achieved with phacoemulsification alone or subsequently with nonsurgical options (medications or selective laser trabeculoplasty [SLT]). In addition, the long-term efficacy of MIGS is uncertain, and it is not without risks.
“Keep calm and play the long game,” Dr Tatham advised. “Lifetime risk of glaucoma is often low for patients with OHT, and there is a lack of evidence to support performing MIGS in patients with cataract and OHT.”
He cited findings from the landmark Ocular Hypertension Treatment Study (OHTS) to support his reasons, indicating a low risk of OHT progressing to glaucoma.
“At 5 years, more than 90% of untreated patients in the OHTS did not have glaucoma, and at 13 years, almost 80% of patients allocated to observation still did not have glaucoma,” he said.
As a caveat, Dr Tatham noted the need to individualise target IOP and treatment. While calculators for estimating glaucoma risk help, it is imperative to remember the information is an estimate only of the likelihood of developing glaucoma.
“It might be early glaucoma that is not visually significant and not affecting quality of life,” Dr Tatham said.
The OHTS is among other studies and systematic reviews providing evidence phacoemulsification alone can lower IOP. For example, in a subset of OHTS eyes that underwent phacoemulsification, IOP reduced by an average of 4 mmHg or 17% at follow-up at three years.
Furthermore, systematic reviews show the IOP reduction after phacoemulsification in eyes with primary open angle glaucoma (POAG) is modest and declines over time. Similarly, the European Glaucoma Society (EGS) guidelines state reductions in IOP and medications with phacoemulsification in eyes with OAG are typically small. EGS guidelines also do not recommend cataract surgery alone as an intervention to control OAG.
“However, the guidelines do not comment at all on cataract surgery in OHT,” Dr Tatham said.
Discussing the limited information on long-term efficacy of MIGS, Dr Tatham observed that five years is the longest follow-up for randomised controlled trials. Real-world data are available, however, and he cited a study of patients followed for seven years after implantation of two first-generation iStents (Glaukos) combined with phacoemulsification. While IOP reduction sustained over time, the average number of medications used increased.
“The most interesting thing in this study is that 27% of patients died during the follow-up, emphasising it is important to incorporate life expectancy into glaucoma care,” Dr Tatham said.
“We need to avoid cost and side effects of excessive treatment and remember MIGS is only FDA-approved for patients with mild to moderate POAG.”
To highlight the risks, Dr Tatham mentioned the market withdrawal of the CyPass Microstent (Alcon), found to cause significant endothelial cell loss in patients followed out to five years.
“A limited number of MIGS studies have reported endothelial cell loss beyond two years,” Dr Tatham observed.
Reasonable IOP-lowering alternatives
If patients need IOP lowering after undergoing phacoemulsification alone, Dr Tatham advised SLT as a good option. It has a strong recommendation from the EGS as a first-choice OAG treatment. And after three years in the LiGHT study, SLT was shown effective for maintaining target IOP without medication in 74% of eyes and appeared to reduce the need for filtering surgery.
Topical therapy is also a viable modality.
“Drops get bad press, but a European survey of 793 glaucoma patients found most were satisfied with topical therapy,” he explained. “Admittedly, 91.5% of patients were on monotherapy and 25% were using tear substitutes.”
Although Dr Tatham provided multiple reasons why surgeons should perform phacoemulsification only for patients with symptomatic cataract and OHT, he suggested MIGS might have a role if the individual’s glaucoma risk is very high and other circumstances exist.
“If a patient has all of these factors—very high IOP, SLT was not effective, inability to instill drops, drop intolerance, and field loss in the fellow eye—perhaps MIGS is reasonable,” he said.
Safety and efficacy of MIGS
Reviewing the dual procedure, Simonetta Morselli MD identified factors that could favour adding MIGS to cataract surgery, but noted there are cons to consider.
Dr Morselli defined MIGS as a minimally invasive procedure that reduces IOP with an ab interno approach without conjunctival dissection. Angular MIGS provides aqueous humour deflux through the trabecular meshwork and Schlemm’s canal using implanted stent(s) or tissue removal.
“As defined, angular MIGS is effective, quick, and safe. We can customise its approach to the patient’s preoperative condition, and the postoperative course of phacoemulsification plus MIGS is similar to cataract surgery alone,” said Dr Morselli, listing the “pros” for the dual procedure.
Identifying the “cons,” she said “MIGS is expensive, can be uncomfortable for the surgeon and the patient, and has a slow learning curve due to the challenge of achieving adequate angle visualisation.”
Her discussion focused on the positive experience her institution gained performing angular MIGS procedures with phacoemulsification in eyes with OAG and angle closure glaucoma due to cataract. The patients had mild to moderate glaucoma, and the indications for adding MIGS were to reduce medication use and address medication compliance issues.
Dr Morselli’s group has the longest and largest experience with the iStent inject®. She reported that among 70 patients followed for 12 to 18 months, IOP was reduced by an average of 20%, and 50% of eyes required no postoperative IOP-lowering therapy.
She reported outcomes for follow-up of one year in 10 patients who had MIGS with the Omni system (Sight Surgical). In this cohort, mean IOP reduction was also 20%, and 80% of eyes required no additional therapy for IOP lowering.
The group also has experience with high-frequency deep sclerectomy, which is limited to 11 patients. At three months, IOP was reduced by an average of 10% without any eyes needing additional therapy. However, Dr Morselli noted HFDS is a painful procedure and requires more intensive medication to control inflammation.
Referring to the outcomes she reported for the iStent inject, Omni Surgical System, and HFDS, Dr Morselli said, “The literature supports our good results.”
She mentioned the Trabectome system, excimer laser trabeculostomy, and Hydrus Microstent (Ivantis) are other angular MIGS options, citing published data showing good and stable outcomes after follow-up ranging from two to three years.
The debate took place during the Glaucoma Day session of 40th Congress of the ESCRS in Milan.
Andrew J Tatham MBChB Hons, FRCOphth, FRCSEd, FEBO, AFHEA is a Consultant Ophthalmic Surgeon, Princess Alexandra Eye Pavilion, Edinburgh, Scotland, United Kingdom. firstname.lastname@example.org
Simonetta Morselli MD is chief of the department of ophthalmology at San Bassiano Hospital, Bassano del Grappa, Italy. email@example.com
Cheryl Guttman Krader
Thursday, March 2, 2023