March 2019

COVER FEATURE

Refractive corrections
Making room in the toolbox for the toric ICL


by Vanessa Caceres EyeWorld Contributing Writer




Visian ICL
Source: STAAR Surgical

Careful marking of the horizontal axis in a supine position is of the utmost importance.
Source: Erik Mertens, MD

The toric marking lines on the toric ICL are useful to correct the astigmatism in the right axis.
Source: Erik Mertens, MD


Now approved in the U.S., toric ICL offers a correction option for high myopes with astigmatism

Approval of the Visian Toric Implantable Collamer Lens (ICL, STAAR Surgical, Monrovia, California) in the U.S. gives refractive surgeons another option to correct high myopia and astigmatism.
The toric ICL was approved by the U.S. Food and Drug Administration in September of last year and became available to surgeons in the fall.
“We have been anxiously awaiting the approval for many years,” said Lance Kugler, MD, Omaha, Nebraska. Before the approval, the typical surgical option for Dr. Kugler’s patients with high myopia and astigmatism was treating the myopia with an ICL and the astigmatism with a corneal procedure such as LASIK. Although effective, “many patients are not candidates for LASIK, and the staged procedure adds logistical complexity, so an all-in-one solution is a welcome addition to our vision correction surgical options.”
“Being able to correct myopia and astigmatism with a phakic IOL does not compromise the integrity of the cornea, does not induce dry eye, and gives excellent and stable quality of vision,” said Erik Mertens, MD, Medipolis, Antwerp, Belgium.

Best candidates

U.S.-based surgeons are still tweaking their recommendations for who is best suited for the lens.
Paul Dougherty, MD, clinical instructor, Jules Stein Eye Institute, University of California, Los Angeles, finds that the best candidates for the toric ICL are those with more than a diopter of cylinder and a refraction of more than –8 D. “I think patients who are a –8 D benefit from an ICL over LASIK because of the sharper vision, having the correction closer to the nodal point, and the contrast sensitivity at night is better in the moderate myopes.”
Gregory Parkhurst, MD, San Antonio, recommends starting with the “low-hanging fruit” of patients who do not qualify for laser vision correction (LVC). He gave the example of a patient he recently saw for a consultation who was a –16 D. The toric ICL ranges from –3 to –16 D so the patient will have the highest correction possible, but she likely will be able to drive herself to the day 1 postop appointment, and there will be no tissue removal or altering, Dr. Parkhurst said.
Correction in these patients often provides a “wow” factor that is associated with higher patient satisfaction, surgeons said.
After starting with non-laser candidates, Dr. Parkhurst found that choosing an ICL (including a regular ICL before the toric was available) has become a top-line solution even in patients who qualify for LVC. He cited his own research that found slightly better night vision quality in patients who had ICLs versus LASIK, although both groups performed better than in their glasses.1
There is another advantage that Dr. Parkhurst sees.
“Doing phakic IOLs preserves the cornea for future milestone development, such as presbyopia in a patient’s 40s and 50s and a cataract later on,” he said.
Dr. Parkhurst will add a personal touch when necessary by letting patients know that among the four physicians at his practice, three of the spouses—including Dr. Parkhurst’s wife—have had ICLs for years and are happy with their vision.
Patients with certain pathology that may limit other corrections—for instance, a thin cornea, severe dry eye, or stable keratoconus—can benefit from the toric ICL, Dr. Dougherty said.

Surgical challenges and tips

Just like with any new technology, use of the ICL can present with challenges, especially at first. Here are some tips that seasoned surgeons shared to make ICL use more seamless.

1. Practice alignment with the astigmatism. “The toric ICL requires a slightly different mindset than a toric IOL because the latter is correcting only the corneal astigmatism whereas the ICL is treating the refractive astigmatism,” Dr. Kugler said. “Though the majority of refractive astigmatism arises from the cornea, the alignment of the ICL may be slightly different than the axis of cylinder seen on topography.”
Dr. Mertens marks the horizontal axis of the cornea in a supine position so the toric ICL can be aligned accordingly to rule out cyclotorsion errors when the patient is lying on the operation table.2

2. Size appropriately. “Proper measurements are critical to selecting the right size of the Visian ICL,” Dr. Dougherty said. He has a published nomogram based on sulcus-to-sulcus measurement to properly size the lens.3 “There are four sizes to choose from, and using ultrasound biomicroscopy [UBM], my sizing is more accurate than any other technique available,” he said. He also still uses the Online Calculation and Ordering System from STAAR Surgical for spherical and astigmatic power calculation.
Dr. Parkhurst also uses UBM technology to measure sizing. “The UBM has been an important tool to get the sizing right,” he said.

3. Stay aware of potential sizing mishaps. Sizing of the ICL is the biggest challenge of the lens, according to Dr. Parkhurst, noting that a too big lens could lead to IOP rises, pupillary block, or angle closure. “In the first 24 hours, the surgeon needs to have their cell phone on and if the patient has pain, nausea, or a headache, they should call immediately. This usually indicates the ICL was oversized and that the angle is closed,” he said. If the ICL is too small and not sufficiently in the sulcus, the ICL is at risk of rotation. “I tell my patients it’s like Goldilocks. The sizing needs to be just right,” Dr. Parkhurst said.

4. Consider vertex distance of the refraction. This may not be important with lower myopes, but it can make a difference with higher myopes, Dr. Parkhurst said. “That subtle 1 or 2 mm of distance can throw things off significantly,” he said. “We often employ a contact lens overrefraction, so let’s say someone is –12 D, we’d put in a –10 lens and refract to –2 from there. That minimizes the effect of vertex to get the refraction right.”

5. Eliminate dry eye in advance. This can help exclude refractive errors, said Dr. Mertens, who also uses anterior and posterior corneal topography to reduce the chance of surgical surprises.

6. Educate patients in advance on visual quality. Patients with keratoconus or subclinical keratoconus may still have some astigmatism, Dr. Kugler said. If these patients are used to wearing scleral or gas permeable contact lenses, they may be dissatisfied with the toric ICL visual quality. Let patients know about this potential outcome, and tell them that they may not be able to wear these lenses after implantation.

One additional pearl

In addition to the surgical learning curve, Dr. Dougherty shared one more suggestion to maximize your use of the toric ICL.
Beef up your marketing. There’s obviously a lot more awareness about LASIK, Dr. Dougherty said, but when consumers know someone with the ICL, they are more eager to book the day of consultations than those hearing about the technology for the first time, he explained. To boost awareness, his practice markets the Visian ICL on its website, through social media, to their optometrist network, and directly to consumers through public relations efforts.

References

1. Parkhurst GD. A prospective comparison of phakic collamer lenses and wavefront-optimized laser-assisted in situ keratomileusis for correction of myopia. Clin Ophthalmol. 2016;10:1209–15. 
2. Mertens E. Posterior Chamber Toric Implantable Collamer Lenses – Literature Review. Astigmatism – Optics, Physiology and Management. 2012:181–192.
3. Dougherty PJ, et al. Improving accuracy of phakic intraocular lens sizing using high-frequency ultrasound biomicroscopy. J Cataract Refract Surg. 2011;37:13–8.

Editors’ note: Drs. Dougherty, Mertens, and Parkhurst have financial interests with STAAR Surgical. Dr. Kugler has no financial interests related to his comments.

Contact information

Dougherty
: flapzap@gmail.com
Kugler: lkugler@kuglervision.com
Mertens: E.Mertens@medipolis.be
Parkhurst: gparkhurst@parkhurstnuvision.com

Making room in the toolbox for the toric ICL Making room in the toolbox for the toric ICL
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