Innovative implantable collamer lens expands options for higher myopes
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Intraocular lens surgery was once seen as a last resort for patients interested in spectacle independence, but that paradigm has shifted with the advent of the EVO Visian implantable collamer lens.
The lens, created by STAAR Surgical, has been part of the refractive surgery landscape outside of the United States for well over a decade. During this time, we have successfully employed this posterior chamber refractive intraocular collamer lens (ICL) at TLC Laser Eye Centers in Ontario, Canada, to exceed the visual freedom demands of thousands of patients.
EVO lens in situ with visible central port for aqueous flow. Source: Anu Ondhia, OD
Our EVO patients experience the day-1 “wow” factor historically associated with LASIK — without the ocular surface issues typically linked to corneal refractive surgery. Now that EVO is available in the U.S. following recent FDA approval, I’d like to share some pearls with my fellow optometric colleagues who will be managing the pre- and postoperative processes of this procedure that is so well-aligned with the skillset and expanded scope of today’s optometrists.
A new generation of ICL
Earlier generations of ICLs were hampered by the risk for anterior subcapsular cataract (ASCs), pupillary block (angle closure) and endothelial cell loss among other concerns, and thus were typically relegated to patients who were not viable candidates for LASIK.
EVO, which is FDA-approved for treatment of 3 D to 20 D of myopia and 1 D to 4 D of astigmatism, has transcended these barriers to adoption, with its advanced design and proven outcomes. EVO is the next generation version of the original Visian ICL.
The single most important distinction between EVO and its predecessor is a patented 360 µm central port, which eliminates the need for preoperative peripheral iridotomy (PI). This design nuance practically eliminates EVO’s risk for ASC and pupillary block. Outcomes from 4,000 patients — with up to 5 years of follow-up — demonstrate that no patient developed a visually significant ASC (Kamiya K, et al).
Patient selection and counseling
EVO ICLs achieve notably high levels of postoperative uncorrected distance visual acuity, refractive predictability and stability. Remarkably, EVO ICL often has been shown to produce postoperative vision that is better than preoperative acuity because of its ability to correct such a variety of moderate to extreme prescriptions without altering corneal curvature and thickness (Kamiya K, et al).
In a STAAR clinical trial, average postoperative vision was better than 20/20, and in the more recent toric EVO ICL study, approximately 75% of patients gained at least one line of vision. While higher myopes are understandably well-suited to EVO, we find that patients who have a moderate amount of myopia are excellent candidates for this lens because of superior visual outcomes.
One benefit of the EVO ICL that resonates well with both patients and doctors is that it is removable. This becomes important years after implantation if — or more likely when — the patient develops an age-related cataract. Because no tissue has been removed, the virgin eye gives the patient and surgeon more flexibility with respect to IOL choice and desired refractive outcome. While it is not likely top of mind for younger patients, those approaching presbyopia appreciate the foresight.
Pre-, postoperative care
The steps taken to prepare patients for ICL surgery are similar to those required for LASIK: Patients forgo contact lenses for a week and, in some cases, a steroid taper or punctal plugs ensure the ocular surface is optimized for effective diagnostic measurements and prime healing.
The two most important measurements used to gauge EVO candidacy are manifest refraction and anterior chamber depth (ACD). The STAAR study required an ACD of at least 3 mm from posterior surface of the cornea to the anterior surface of the crystalline lens.
Precise white-to-white measurements determine implant sizing. The white-to-white can be measured with various devices, such as calipers, a Pentacam (Oculus Inc.) or an Orbscan corneal topographer (Bausch + Lomb). Through experience, we have found the Orbscan to provide the most accurate assessment, and all other lens calculations are obtained via STAAR Surgical’s proprietary OCOS online calculation software.
EVO implantation takes about 10 minutes under optional twilight sedation. The patient is assessed 4 to 6 hours postoperatively to ensure there is no IOP spike and again the next day for further evaluation. At this visit, we gauge EVO positioning via the lens vault, which ideally should be 250 to 750 µm (or 0.5 to 1.5 central corneal thickness). At the 1-month follow-up visit, we confirm that the angles able to be occluded.
Benefits outweigh risks
While patients are not especially moved by the fact that no PI is needed for this lens, surgeons are very impressed. Though PI-associated risks for infection, inflammation and dysphotopsia are low, they do exist and any opportunity to eliminate risk is advantageous.
Like many teams, ours was cautious to enter the EVO realm. We have long since forgotten those days and enjoy the overwhelmingly positive outcomes and feedback from our ecstatic patients every day.
Overall, the EVO Visian ICL benefits patients with unparalleled visual outcomes, frees up surgeons to focus on surgery and provides optometrists with broader opportunities for medical comanagement.
References:
- Kamiya K, et al. PLoS One. 2013;doi:10.1371/journal.pone.0066846.
- Kamiya K, et al. J Cataract Refract Surg. 2008;doi:10.1016/j.jcrs.2008.06.030.
- STAAR Visian Toric ICL post-approval study (TICL-PAS). https://clinicaltrials.gov/ct2/show/NCT04516772. Published Aug. 18, 2020. Accessed Sept. 22, 2022.
For more information:
Anu Ondhia, OD, is clinical director at TLC Laser Eye Centers and glaucoma and anterior segment surgery team associate at Prism Eye Institute in Ontario, Canada. She can be reached at anuondhia@gmail.com.
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