enVista Envy™ Toric: Low-Cyl Technology
Recently, Dr. Adam Muzychuk, clinical assistant professor of surgery at the University of Calgary, the scientific meeting chair for the Eye Physicians and Surgeons Association of Alberta, and the skills transfer course director for Cornea and External Disease for the Canadian Ophthalmological Society, discussed the enVista Envy™ full range of vision (FROV) IOL, focusing on the Low-Cyl technology of the enVista Envy Toric lens and the performance of the enVista Envy lens in the pivotal Canadian study for which he was an investigator.
Expanding Premium Options for the Treatment of Low Astigmatism
A significant number of patients with astigmatism go uncorrected.1 If left uncorrected, astigmatism can ultimately lead to decreased productivity due to visual errors, posing an economic burden on working-age adults.1
According to Dr. Muzychuk, “large and well-designed studies have demonstrated residual refractive cylinder as little as 0.5 diopters (D) can have deleterious effects on visual outcomes following IOL surgery.” These effects can compromise functional and low-contrast visual acuity and the ability to perform computer tasks comfortably.2,3 Additionally, 74% of cataract patients have less than 1.25 D of corneal astigmatism.4
The enVista Envy Toric lens expands premium options for low astigmatism treatment as part of the only IOL platform that corrects <1.0 D astigmatism at the corneal plane.5 Dr. Muzychuk noted that this platform further refines the ability to correct even the smallest amounts of visually significant cylinder.
Low (1.25 D) Cyl technology on the enVista platform allows the surgeon to simultaneously treat presbyopia and astigmatism, reducing the need for additional refractive correction procedures.6 The enVista Envy Toric offers surgeons greater precision in cylinder correction than any other platform, offering powers of 1.25 D, 1.50 D, and 2.0 D, followed by 0.5 D steps up to 3.5 D, and then 4.25 D, 5 D and 5.75 D.5-9 With the Emmetropia Verifying Optical formula, a higher percentage of patients, about 80%, are in the 0 to 0.5 D range compared with traditional vergence formulas.10
The enVista Envy Toric lens is the first and only toric platform providing Low-Cyl toric technology. In the US, the lens is available in a 1.25 D cylinder version,5 and in Canada, the lens is available in a 0.9 D cylinder version.6
enVista Envy: Canadian Study
Dr. Muzychuk explained, “I was one of nine investigators in the pivotal Canadian clinical trial who implanted enVista Envy bilaterally in 111 subjects, for a total of 222 eyes. I was excited about this opportunity because I hadn’t yet found a trifocal lens that I wanted to consistently recommend, and I enjoy using the enVista as my go-to monofocal and toric platform.” This was a prospective, randomized, controlled clinical study. Patients with bilateral cataracts were enrolled at one of nine study sites in Canada and randomized to receive either enVista Envy lenses bilaterally or enVista monofocal lenses bilaterally. They were followed up to postoperative Visit 4, which occurred from Day 120 to Day 180 after the IOL implantation in the second eye.11
The two groups had similar distance vision, as shown by the similar peaks near 20/20 at 0.0 D. However, in the intermediate and near vision range (-1.5 to -2.5 D), the enVista Envy group demonstrated a plateau at approximately 20/25, whereas the enVista monofocal group decreased from approximately 20/40 to 20/60. The FROV IOL advantage was maintained throughout the extended near vision range (-2.5 to -3.5 D).11
enVista Envy Defocus Curve11
D, diopter; logMAR, logarithm of the minimum angle of resolution.
Dr. Muzychuk was very impressed with the patient-reported outcomes from the Canadian study. He noted, “Patients are ultimately choosing a trifocal to gain spectacle independence, and 90% of patients reported little to no difficulty completing activities without glasses.” In addition, 91% of patients reported little to no difficulty reading their cell phone, 94% had little to no difficulty viewing close objects, 83% of patients reported little to no difficulty seeing closer objects in poor or dim lighting conditions, and 95% reported little to no difficulty reading their computer screens. For patients performing activities in which objects move between the set focal points, for enVista Envy, 95% of patients reported little to no bothersomeness in judging distance or depth perception.11 Dr. Muzychuk also pointed out, “With the advancements made in IOL design to achieve spectacle independence, we should be very optimistic that most patients will be able to neuroadapt to the Envy optic.”
Photic phenomena, especially glare and halos, are known effects of IOLs with multiple foci.12-15 “Glare, halos, and starbursts, collectively referred to as dysphotopsias, were some of the adverse effects that limited the number of patients who wished to consider FROV technology and gave some surgeons pause to recommend these IOLs,” Dr. Muzychuk notes. One of the most striking findings of the Canadian clinical trial (n=110) was the patient-reported bothersomeness to dysphotopsias with enVista Envy, which was optimized to reduce these adverse visual effects. In this study at the 4-6 month post-op visit, 95.5% of patients were “not at all” or “a little” bothered by glare, 88.1% for halos, and 93.6% for starbursts.11 “These patient-reported rates of dysphotopsias are stunningly low and very close to what you might expect from non-diffractive technologies such as extended depth of focus (EDOF) lenses.”
enVista Envy: US Study
Excellent results were also reported from the pivotal US Clinical Study, in which 501 subjects underwent cataract surgery and bilateral implantation of either the enVista Envy lens (n=332) or the enVista monofocal lens (n=169). In this study, enVista Envy achieved excellent mean visual acuity results.11
Mean Visual Acuity Results 4-6 Months Post-Op11,a
a enVista Envy US Clinical Study, bilateral implantation, 4-6-month post-op
Conclusion
In closing, Dr. Muzychuk noted that “the range of vision and patient-reported outcomes of the Canadian study have convinced me that the enVista Envy delivers on its promise of providing intermediate and near vision range with a favorable dysphotopsia profile. As a surgeon who had moved to deploying more and more non-diffractive EDOFs in recent years for patients desiring reduced dependence on spectacles, I will now be reassessing my patient counseling regarding FROV IOLs to take into account the advancements noted in the Canadian study of enVista Envy.”
Adam Muzychuk, MD, is a clinical assistant professor of surgery at the University of Calgary, the Canadian Ophthalmological Society Annual Meeting chair, the scientific meeting chair for the Eye Physicians and Surgeons Association of Alberta, and the skills transfer course director for Cornea and External Disease for the Canadian Ophthalmological Society. He received his medical degree and completed his residency at University of Calgary in Alberta, Canada, and completed his fellowship at the University of Montreal, Montreal, Canada.
Financial disclosure: consultant to Bausch + Lomb