Topography-guided procedure raises the bar in laser vision correction outcomes

February 1, 2016

Topography-guided LASIK is a new option for treatment of myopia with or without astigmatism.

Take-home message: Topography-guided LASIK is a new option for treatment of myopia with or without astigmatism.

Reviewed by Karl G. Stonecipher, MD

Chapel Hill, NC-A unique treatment that personalizes the ablation to the cornea-topography-guided LASIK (Contoura Vision, Alcon Laboratories)-is delivering unsurpassed visual quality and quantity outcomes, said Karl G. Stonecipher, MD.

The treatment is the first topography-guided LASIK to receive FDA approval. It is performed using the WaveLight Topolyzer Vario Diagnostic Device, proprietary treatment planning software, and either the Allegretto Wave Eye-Q or WaveLight EX500 Excimer Laser systems (all Alcon).

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It is indicated for use in patients ages 18 years and older for the reduction of up to –9 D of spherical equivalent (SE) myopia or myopia with astigmatism, with up to –8 D of spherical component and up to –3 D of astigmatic component in the spectacle plane. Treated eyes should have a normal cornea (e.g., normal thickness and only minor variations in topography, such as an asymmetric bowtie pattern) and stable refraction.

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“Contoura Vision represents an additional option for improving our outcomes with laser vision correction,” said Dr. Stonecipher, who was an investigator in the study and is clinical associate professor of ophthalmology, University of North Carolina, Chapel Hill. “It normalizes the cornea, optimizing the optics, and in the U.S.-based multicenter clinical trial, it was associated with amazing results for improving objective visual acuity measurements and, most remarkably, for improving visual symptoms.”

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Visual acuity

 

A total of 249 eyes were treated in the multicenter clinical trial, of which 230 were evaluated at 12 months. Visual acuity measurements at 12 months showed uncorrected visual acuity (UCVA) was 20/20 or better in 92.7% of eyes, 20/16 or better in 68.9%, and 20/12.5 or better in 31.6%.

“Compared with the preoperative best spectacle-corrected visual acuity (BSCVA), postoperative UCVA was better by 1 or more lines in 29.6% of eyes and equal to or better in 60.3%,” Dr. Stonecipher said.

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In addition, the refractive outcomes were accurate and stable. Mean postoperative MRSE at 12 months was 0.06 D and the mean achieved surgical correction was nearly the same as the intended surgical correction, 1.23 D MRSE versus 1.27 D MRSE.

Contrast sensitivity was also measured, and the results showed improvements under mesopic and photopic conditions across all spatial frequencies.

Furthermore, many patients benefited with improvement of existing visual and/or ocular symptoms. Compared with preoperatively, reports of marked to severe problems with light sensitivity, difficulty driving at night, reading difficulty, fluctuation in vision, glare, halos, starbursts, dryness and pain were all reduced after the topography-guided procedure.

The difference between the proportions of patients with marked to severe problems preoperatively versus postoperatively was statistically significant for light sensitivity, difficulty driving at night, reading difficulty, and glare.

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“This is the first LASIK clinical trial in which we have ever seen statistically significant improvements in these visual symptoms,” said Dr. Stonecipher, who is also medical director, TLC Greensboro, Greensboro, NC.

Safety was excellent. BSCVA was 20/40 or better in all eyes. Eye dryness was the most commonly reported issue in the first 3 months after surgery.

“Compared with baseline, however, there was a 1.6% decrease at 3 months in the incidence of moderate to severe eye dryness,” Dr. Stonecipher said.

Ninety-eight percent of patients said they would have the topography-guided LASIK procedure again. 

Personal insights

 

Watch as Karl G. Stonecipher, MD, demonstrates a unique treatment that personalizes the ablation to the cornea-topography-guided LASIK (Contoura Vision, Alcon Laboratories). (Video courtesy of Karl G. Stonecipher, MD)

Personal insights

Dr. Stonecipher said that the results he is achieving with the topography-guided LASIK procedure match or surpass those achieved in the clinical trial, even as he is still working to refine his nomogram.

“All of my patients are seeing 20/20 or better uncorrected on postop day 1, almost three-fourths are achieving 20/16 or better UCVA, and around 10% are 20/10,” he said.

Dr. Stonecipher noted that he is now performing a topography-guided procedure in about 30% of his LASIK population, and he is finding that querying patients about existing visual symptoms can be a guide to identifying good candidates.

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“The topography-guided LASIK procedure  has opened the door for us in terms of reducing visual symptoms that can be induced with other LASIK approaches,” he said. “For that reason, I have begun to be more proactive in asking patients whether they have problems with glare, halos, starburst, or difficulty driving at night as that can be a clue to some subtle topographic abnormality.”

Obtaining good preoperative topography is requisite to achieving good results.

“As with conventional or wavefront-guided LASIK, noise in equals noise out, and with the topography-guided LASIK procedure, the planning software will not work without reliable topography,” Dr. Stonecipher said.

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Therefore, candidates should be carefully evaluated and treated for ocular surface disease preoperatively.

“About one-third of my refractive surgery population comes in with some type of ocular surface disease,” he said. “When performing topography-guided LASIK, we want to be sure that the topography reflects real abnormalities in the corneal surface and not an irregularity related to ocular surface disease and a poor tear film.”

Because the ability to perform topography-guided LASIK and its outcome depends on the quality of the diagnostic information, it involves some extra work preoperatively on the part of the technician and the surgeon. The technician has to obtain high quality topographic images with a reproducible map over at least 70% of the cornea, and the surgeon has to review the images against the treatment plan to confirm the ablation will achieve the manifest refraction goal.

Be conservative

 

Be conservative

Although the  indication for the topography-guided LASIK procedure allows treatment of up to –9 D SE, Dr. Stonecipher said refractive surgeons would do best to limit their selection of patients initially to “easier cases” that he described as eyes with up to –4 D of myopia and up to –2 D astigmatism.

“My advice is to start low and slow because there is a challenge and some art to topography-guided LASIK planning,” Dr. Stonecipher said. “Assuming one might have 10% error in refractive accuracy initially, it will be much less of an issue treating an eye with a lower than a higher SE. That is why any surgeon starting with a new laser or new software should start low and work up.”

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He also cautioned that while refractive surgeons outside of the United States, where topography-guided LASIK has been available for some years, are using it to address “20/unhappy patients” with aberrated corneas associated with previous refractive surgery or keratoconus, the platform is not approved for such use in the United States. This application requires further development, Dr. Stonecipher said.

“We have learned from the international experience with topography-guided LASIK that one can do some real harm trying to fix a 20/unhappy eye with a highly aberrated cornea,” he said. “While we are moving in the direction of treating irregular corneas, topography-guided LASIK is not indicated for those eyes at this time.”

 

Karl G. Stonecipher, MD

E: stonenc@aol.com

Dr. Stonecipher is a consultant to and receives lecture fees from Alcon Laboratories, Abbott Medical Optics, Bausch + Lomb, and WaveLight AG, and he receives grant support from WaveLight AG.