As both the rate and magnitude of myopia continue to rise, U.S. corneal surgeons welcomed the availability of the EVO Visian Implantable Collamer Lens (ICL) (STAAR Surgical), FDA-approved in 2022, to treat these patients.
Here, I provide the pre-, intra-, and postoperative pearls for using this ICL to both increase the likelihood of patient satisfaction and facilitate its use.
The Preoperative Evaluation
Patient Selection: On label, the EVO Visian ICL can treat myopia from -3.0 D to -15.0 D, reduce myopia up to -20.0 D, and treat astigmatism from 1.0 D to 4.0 D in patients ages 18 to 45. Additionally, the patient’s true anterior chamber depth (ACD), which is measured endothelium to anterior lens capsule and does not include corneal thickness, must be at least 3.0 mm for the on-label use of the ICL. That said, if the angle anatomy is open, as confirmed by anterior-segment (AS)-OCT, I’m often comfortable using the EVO ICL on patients who have an ACD ≥2.8 mm. An informed discussion must be had with the patient regarding off-label use to ensure an understanding of both the benefits and possible adverse effects of the ICL to give their informed consent.
Preoperative workup: My typical workup for an ICL patient includes the following:
• Corneal tomography
• AS-OCT (for both angle anatomy and epithelial mapping)
• Optical biometry
• Specular microscopy
One of the most important measurements will end up being the white to white. This measurement determines the ICL length (currently 12.1 mm, 12.6 mm, 13.2 mm, or 13.7 mm). Some consider the gold standard for this measurement to be a sulcus-to-sulcus measurement that is obtained via ultrasound. However, availability of this imaging modality is often limited. I rely on the horizontal white-to-white imaging from a tomographer. A manual caliper is used for confirmation whether the recommended size is close on our sizing nomogram. While sizing ICLs using the current methodology has a high success rate, I think this is an area that will continue to improve with the advancement of different imaging modalities combined with advancements in algorithms that utilize machine learning and artificial intelligence.
Pearl: Confirm white-to-white measurements that were optically obtained when between 2 sizes.
The Surgery
Sedation: Setting yourself up for success with appropriate sedation is paramount. I start with a sublingual troche of midazolam, ketamine, and ondansetron about 15 minutes to 20 minutes prior to the case. While I often don’t need it, I still prefer to have an IV for ICL patients. If a patient gets uncomfortable at any point during the case and begins to squeeze or bear down, the posterior pressure can make a case more challenging than it needs to be.
Pearl: Even if not intending to use it, have an IV on all your early ICL patients.
Loading the lens: ICLs consist of a collagen-copolymer and are much softer and more delicate than the IOLs we and our surgical staff handle for cataract surgery. Surgeons should keep this in mind when handling the ICL. It is also important to always keep the ICL hydrated. Avoid using rough or teethed forceps while loading, as these can easily damage an ICL. Minimizing air bubbles in the ICL cartridge will allow for easier visualization of the ICL during injection.
Starting the case: Incision placement is key. I often make my standard paracentesis (para) for my non-dominant hand in a radial fashion, pointing toward the center of the eye. It’s an incision I often don’t need, but when I do, I’m glad it’s there. I follow with a para for my dominant hand that is more tangential in fashion, pointing toward the patient’s nose (Figure 1). Angling this incision toward the nose allows for easy tucking of the leading footplates of the ICL into the sulcus without too much torque on the incision. If the surgeon plans to irrigate through either of their paras at the end of the case, they should consider enlarging them slightly.
Figure 1. Here are my incisions for a standard ICL case. I prefer to create a para for my dominant hand that is directed toward where the leading footplates will be tucked.
I then instill preservative-free lidocaine with epinephrine followed by the recommended ocular viscosurgical device (OVD). I find that the epinephrine gives the iris a little more rigidity, which allows for easier irrigation at the end of the case. During OVD injection, it is important to not overfill. Our instinct as cataract surgeons is to overfill the anterior chamber with OVD; during ICL surgery the OVD-fill should be ~2/3rds or less. This allows for easier tucking of the ICL by preventing the iris from being pushed too posterior into the phakic lens. It is also important to remember that the more OVD that is injected, the more that needs to be removed at the end of the case. Finally, a main incision is created (2.75 mm to 3.2 mm).
Pearls:
• Epinephrine can help give the iris tone, which can facilitate easier irrigation at the end of the case.
• Make your incisions in directions that facilitate the work you’ll do through them; consider slightly enlarging the paras if you plan to irrigate through them.
• Don’t overfill the anterior chamber with OVD.
ICL injection: When injecting the ICL, the surgeon will encounter a small amount of resistance. Pushing too fast through this resistance can result in an uncontrolled injection. Instead, gently push through the resistance, so the ICL will begin to unfold in the eye.
The leading eyelet should be to the right; you can rotate the injector while injecting to keep it there.
At this stage, it is important for the surgeon to ensure the leading corner of the ICL that contains an eyelet is to the right. This ensures the ICL is right side up and that the vault is in the correct direction (“right is right”). As the ICL unscrolls, the surgeon can keep the eyelet to the right by twisting the injector if necessary. If the ICL is inserted upside down, it must be corrected either by flipping it inside the eye (a difficult maneuver that can cause damage to the phakic lens or the endothelium) or explanting it. If damage to the ICL is sustained during explantation, the ICL should not be re-implanted.
Pearl: The leading eyelet should be to the right; you can rotate the injector while injecting to keep it there.
ICL positioning: When inserted, the ICL essentially glides on top of the previously placed OVD. To avoid damaging the endothelium, the surgeon can use a small amount of OVD on top of the ICL both proximally through the main incision and distally through a paracentesis. Again, the surgeon should avoid overfilling. Now, the surgeon can use a manipulator to tuck first the distal and then the proximal foot plates under the iris into the sulcus. The surgeon should take care not to pass instruments over the optic, as the soft collamer material can be damaged.
Irrigation: Once the lens is correctly orientated, the OVD can be irrigated out of the eye using balanced salt solution (BSS) on 5cc syringes with 27 g cannulas. As stated previously, if irrigating through a para, the surgeon should consider enlarging it slightly. This prevents IOP spikes, which can happen quickly and cause iris prolapse and extreme patient discomfort. The main incision can also be used, which is a personal preference. If irrigating through the main incision, the surgeon should ensure a proper instrument angle and minimize posterior pressure on the lip of the wound to avoid wound gape, which can lead to iris prolapse. The surgeon should direct BSS toward either edge of the ICL and create a vortex motion of BSS by methodically letting IOP slightly build and then burping the wound. The surgeon should not inject BSS directly through any of the ports. If the iris prolapses at any point, the surgeon should remember to first lower the IOP through a para before delicately repositing it.
After all, or most, of the OVD is removed, the surgeon should ensure the incisions are sealed. A miotic can be used but isn’t necessary. If using carbachol, consider a 1:3 dilution to prevent postoperative headaches and prolonged miosis. Intracameral antibiotics, while off label, can be used at the surgeon’s preference.
Pearls:
• The key to successful irrigation is creating a vortex movement of BSS by slowly pulsing the plunger.
• Avoid IOP spikes by burping the wound being irrigated.
Postoperative Care
In addition to the standard postop-day-1 appointment, a same day postoperative IOP should be checked within a few hours of surgery. While a 250 µ to 750 µ vault is preferred (best measured by AS-OCT), the vault seen in the first couple days postop may not reflect the ICL’s final resting vault (Figure 2). The EVO ICL is more forgiving of both higher and lower vaults; however, angle closure and cataract formation are still risk factors to monitor for. Beyond the first year of follow-ups, we recommend our patients see an eye provider familiar with ICLs annually.
Figure 2. Here is a postop-hour-4 photo of an ICL in a patient with a normal IOP. There is no vault (A).
Here, the same eye can be seen with a normal vault 1 week later (B).
Something to Consider
With myopia on the rise, more surgeons are implanting ICLs now more than ever. The EVO ICL has greatly simplified this process for American surgeons. Surgeons should not for-get these important surgical pearls when they begin using the EVO in their practice. CP
