Challenges are linked with refractive surgery for myopia and astigmatism

(Image Credit: Adobe Stock/Дмитрий Ткачук)

Blake K. Williamson, MD, MPH, MS, shares his suggestions for using implantable contact lenses (ICLs) for some patients who may
not have been previous candidates for the technology. Williamson is a cataract and refractive surgeon in private practice in Baton Rouge, Louisiana.

CASE 1: ICL for low myopia and astigmatism

A 36-year-old man being evaluated for refractive surgeries reports blurry vision and desires some spectacle independence. The spectacle distance–corrected vision is 20/30 in the right eye and 20/25+ in the left eye, and the respective uncorrected visual acuities (VAs) are approximately 21/50 and 22/50. In the right eye, the manifest refraction is approximately –3.00 D +2.00 × 23 for a best-corrected distance acuity (BCVA) of 20/16-2. In the left eye, the manifest refraction is –4.75 +1.25 × 151 with a BCVA of 20/16.

The astigmatic topography is normal, but the corneal pachymetric values are thin: 413 μm in the right eye and 409 μm in the left eye. The retina/macular scans and widefield imaging show normal results.

The red flag in this case is the exceptionally thin corneal pachymetry in a virgin cornea, making this patient an unsuitable candidate for LASIK or PRK. Other options include a refractive lens exchange, but this might be too aggressive in a young patient with myopia. Something safer, less invasive, and reversible might be considered, according to Williamson.

An ICL might be an option. ICLs, Williamson points out, have generally been reserved for patients who are not candidates for LASIK or PRK but have high levels of myopia: –9 D or above. The new ICL (EVO Visian ICL; STAAR Surgical) can address myopia levels as low as –3 D.

Williamson advises that surgeons be mindful of different anatomic parameters when planning surgical correction. For astigmatism, multiple devices should agree on the astigmatic magnitude and meridian, the pachymetry map should be correct, and surgeons should evaluate elevation maps to detect subtle ectasia.

Williamson recommends ICLs to patients who would do well with the optics, including those with a thinner cornea and those with preexisting dry eye disease that might be worsened after LASIK. He also might recommend an ICL for some patients with corneal topography and tomography with some inferior steepening or mild elevation but no other signs of keratoconus. “Whenever I do not want to touch the cornea, I am very confident about implanting an ICL,” he says.

The advantages of ICLs include high patient satisfaction, less pain in the immediate postoperative period, and faster visual recovery than laser vision correction on the cornea. “To be a comprehensive refractive surgeon, you’ve got to be very comfortable with ICLs, even in lower levels of myopia and astigmatism that you might not generally consider,” Williamson says.

CASE 2: Ideal candidate for ICL

This patient is a 39-year-old woman being evaluated for bilateral refractive surgeries. She reports blurry vision and wants spectacle independence. She has worn contact lenses and glasses since the age of 10 years. Her uncorrected VA is 20/320 bilaterally. Her glasses correct –6.50 and –5.50 D in the right and left eyes, respectively. The manifest refraction is similar. Her vision is corrected to 20/20.

The corneal topography and tomography are normal. The right eye has less than 1 D of corneal cylinder, a normal pachymetry map, and normal posterior elevation in the right eye. The left eye is similar, with less than 0.5 D of cylinder and normal pachymetry/elevation maps. The retina and optic nerve are normal.

Williamson discusses factors to consider in cases that appear normal with moderate myopia and astigmatism. He notes that with more LASIK treatments comes the risk for epithelial remodeling, and there can be some drift of the final refractive outcome immediately or within the first 2 years. With PRK, postoperative corneal haze is a concern. When a lens-based approach is considered or high refractive error, retinal tears, or retinal detachments are concerns (especially before posterior vitreous detachment [PVD] occurs), the PVD status should be closely evaluated. A retinal examination is essential for patients with high myopia.

“Some cases of very high myopia, over –9 D, cannot be corrected with other means of vision correction,” Williamson says. “Few surgeons are comfortable doing corneal procedures to correct vision. At some point, the ICL becomes the only procedure to correct very high myopia.”

The current patient could undergo any refractive procedure. This patient appreciates the reversibility of the procedure, less recovery time, quicker visual recovery, and less pain on the first postoperative day. Ultimately, she opts for the ICL.

“The takeaway from this case is that ICL implantation is something patients want. Patients are talking about this to each other [and] having great success with it, particularly with the new ICL that’s just been released here in the United States,” Williamson concludes. “As a result of that, this patient chose this option and did fantastic. I think we should all be offering ICLs in our armamentarium to have the full complement of corrections available for myopia and astigmatism.”

Blake Williamson, MD, MPH, MS
E: blakewilliamson@weceye.com
Dr. Williamson has no proprietary interest in this technology.