Several lens options available for patients who previously underwent refractive surgery
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
This month, Vance Thompson, MD, discusses the merits of implanting the Light Adjustable Lens in patients who previously underwent LASIK or PRK, while Neda Shamie, MD, explains why extended depth of focus and multifocal lenses can provide good results. We hope you enjoy the discussion.
– Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor
Light Adjustable Lens
The post-PRK or post-LASIK patient population is oftentimes the most motivated to have premium refractive cataract surgery and be spectacle independent, so this is an important discussion.
We know that the higher the correction on the cornea, the higher the chance that higher-order aberrations can be induced. It is not unusual for a cornea to be somewhat multifocal after PRK or LASIK, and this is typically an accepted amount of multifocality because patient satisfaction after these procedures is high.
The first thing we do is see how multifocal the cornea is, and we can quantify that with a number of devices. This is an important step to take because we do not want to make the optical system too multifocal. Even if patients are able to read, they are going to be frustrated with their low-light image quality.
That is where the Light Adjustable Lens (RxSight) comes in. With this technology, we can go for a precise monovision result, or if our manifest refraction shows that their vision is good after surgery, we can also induce a little extended depth of focus using the Light Adjustable Lens. The beauty of it is we are doing that postoperatively when the cataract is out, and you can show the patient with a manifest refraction how quality the image is and their various options of both eyes at a distance or the ideal amount of precision monovision for them.
If you had a crystal ball and knew a post-refractive patient was not going to have pristine vision after surgery, you would never use a multifocal IOL. You would use a monofocal. With a Light Adjustable Lens, we have a choice after surgery and are able to get that pristine vision.
Not every patient is a candidate, however. Typically, you want patients whose pupils can dilate to 7 mm or larger. That way, you can illuminate the entire 6-mm optic even if it is not perfectly centered on the dilated pupil. You also want to avoid using the lens in patients who might be on medications that make them sensitive to UV light. Typically, with their general medical doctor’s guidance, they are able to go off their medications for a little while to give you a chance to do the light adjustments, but if not, that would be a contraindication.
In my opinion, for a center that desires to be “the buck stops here” refractive cataract surgery center, the Light Adjustable Lens is an important technology to have.
- For more information:
- Vance Thompson, MD, can be reached at Vance Thompson Vision, 3101 W. 57th St., Sioux Falls, SD 57108; email: vance.thompson@vancethompsonvision.com.
EDOF and multifocal
My preference, typically, is to use a Light Adjustable Lens (RxSight) in the post-LASIK or post-PRK patient because it allows us to avoid a refractive surprise. However, if a patient is not willing to invest in the extra cost or if the surgeon does not have access to the Light Adjustable Lens, then extended depth of focus (EDOF), multifocal and advanced trifocal lenses can be considered and implanted safely in select post-refractive surgery patients.
The important factor to consider would be the corneal topography. If the ablation zone or corneal topographic changes are central to the visual axis and without significant irregularity, and if patient history shows they had excellent vision after their LASIK/PRK, then my assumption would be that the quality of vision that could be obtained with an extended range lens and even a trifocal lens would be not only sufficient but quite good.
I would hesitate to use a multifocal lens in patients with irregular corneas, with ocular surface disease resistant to basic treatments or with a post-hyperopic LASIK or PRK. It comes down to the ocular health. Just because someone had LASIK does not drop them off the list for an EDOF or multifocal IOL. You have to look at the full picture. If the corneal topography is healthy and there is no comorbidity, then patients tend to do well.
Using the right formulas, modifications or nomograms for post-LASIK IOL calculations is critical. Consider using intraoperative aberrometry to get as close to the refractive target as intended. This is particularly true when it comes to multifocal lenses because they are less forgiving of a refractive surprise even if minimal.
- For more information:
- Neda Shamie, MD, can be reached at Maloney-Shamie Vision Institute, 10921 Wilshire Blvd., Suite 900, Los Angeles, CA 90024; email: ns@maloneyshamie.com.
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