A recent study published in Ophthalmology Glaucoma assessed the efficacy and safety of combined cataract surgery with insertion of the iStent Inject (Glaukos Corporation) compared to cataract surgery alone in patients with mild-to-moderate open-angle glaucoma (OAG).
Give me some background.
The advent of microinvasive glaucoma surgery (MIGS) has drastically altered the glaucoma management landscape.
Prior to MIGS procedures, many ophthalmic surgeons relied on either trabeculectomy or glaucoma drainage implantation to manage glaucoma.
However, MIGS procedures now offer intraocular pressure (IOP) reduction with less of the surgical risks associated with traditional incision glaucoma surgeries, such as postoperative hypotony, blebitis, and bleb-related endophthalmitis.
Talk about the iStent Inject.
The iStent Inject is a small, titanium, ab interno trabecular microbypass device designed to create a patent bypass through the trabecular meshwork (TM) to improve physiologic outflow and lower IOP.
As the second-generation iStent device, it primarily differs from the original in that the injector comes preloaded with two iStents (instead of one), and the angle of insertion has changed.
There are limited studies on the efficacy of the iStent Inject, though a previous randomized controlled trial (RCT) of the iStent Inject in combination with cataract surgery found an absolute IOP reduction of 5.4 mmHg vs. 7.0 mmHg in the control and treatment groups, respectively.
Now talk about the study.
In this prospective, randomized, single-center controlled trial, participants' eyes were randomized 1:1 to combined cataract surgery with iStent Inject (56 eyes) or cataract surgery alone (48 eyes).
The study period began in August 2017 and continued through October 2020; eyes with visually significant cataracts and mild-to-moderate OAG with preoperative IOP of 12-30 mmHg and on zero to three ocular hypotensive medications were included.
Investigators followed up with patients for 24 months following cataract surgery.
What were the study endpoints?
The primary effectiveness endpoints were the number of ocular hypotensive medications and IOP at 24 months post-surgery.
Secondary effectiveness endpoints assessed at 24 months included:
- Ocular comfort as measured by the Ocular Surface Disease Index (OSDI)
- Vision-related quality of life (QoL), as measured by the Glaucoma Activity Limitation Questionnaire (GAL-9)
Talk about the cohort.
Participants were 67.3% male, aged 53-85 years, and had similar mean medicated IOP measurements and number of ocular hypotensive medications at baseline.
Mean medicated IOP:
- Treatment group: 17.7 mmHg ± 4.0
- Control group: 17.1 mmHg ± 3.1
Number of ocular hypotensive medications:
- Treatment group: 1.69 ± 1.05
- Control group: 1.80 ± 1.22
Findings?
At 24 months, the number of ocular hypotensive medications was 0.7±0.9 in the treatment group compared to 1.5±1.9 in the control group, with an adjusted difference of 0.6 fewer medications per eye in the treatment arm (95% confidence interval [CI] 0.2-1.1, p = 0.008).
Of note, 57% of eyes in the treatment group were on no glaucoma medications versus 36% in the control group.
Anything else?
There was no significant difference in IOP between the two groups beyond the initial 4 weeks.
Additionally, there were no differences in patient-reported outcomes between the two groups, and the visual outcomes and safety profiles were similar between cohorts.
Expert opinion?
According to the study authors, “Whilst we recognize that MIGS is not a replacement for glaucoma filtration surgery, a sustained reduction in the number of glaucoma medications has clinical utility in that it may defer or reduce the need for filtration surgery in this patient population."
They added: “Furthermore, it is well-established that glaucoma medications are associated with a negative treatment experience as they increase ocular surface disease, treatment cost, as well as reduced adherence with increasing number of medications.”
Take home.
These findings suggest that combined cataract surgery with the iStent Inject in patients with mild-to-moderate OAG reached a clinically and statistically significant greater reduction in ocular hypotensive medication usage at 24 months compared to cataract surgery alone—with no significant difference in IOP.
The study authors also noted that there was a substantial improvement in patient-reported outcomes in the treatment arm—highlighting the success of the intervention outside of IOP parameters alone.