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Aberration-free treatment shows enhanced visual results
The treatment preserves pre-existing higher-order aberrations while compensating for biomechanical changes and correcting for aberrations.
Researchers have demonstrated near perfect results with a LASIK treatment designed to preserve preoperative higher-order aberrations while correcting sphere and cylinder, according to a press release.
 Maria C. Arbelaez |
As part of an international multicenter study conducted in Oman, Germany and the Czech Republic, Maria C. Arbelaez, MD, evaluated the efficacy, safety and predictability of an aberration-free treatment available from Schwind eye-tech solutions.
“With this treatment, the preoperative higher-order aberrations remain unchanged,” Dr. Arbelaez told Ocular Surgery News in an e-mail interview. “The patient retains the habitual sight impression at best focus and the brain requires no learning phase to deal with otherwise added bothersome changes.”
A total of 183 eyes were operated on with the Schwind ESIRIS excimer laser and the ORK-CAM software module.
According to preoperative refraction data, spherical equivalent ranged from –1 D to –11 D, sphere ranged from –0.25 D to –10 D and cylinder was as high as –3 D.
All flaps were created with the Carriazo-Pendular microkeratome (Schwind eye-tech solutions), and ablations were done on optical zones of 6 mm, 6.5 mm or 7 mm.
Follow-up was 6 months.
Study results
The results showed that 71% of all treated eyes were within ±0.25 D of the attempted refraction, 91% were within ±0.5 D and 100% of eyes were within ±1 D.
By the 6-month follow-up, 86% of all eyes had achieved an uncorrected visual acuity of 20/20 or better while only 69% of eyes had a preoperative best corrected visual acuity of 20/20 or better.
The results also showed that the ORK-CAM software successfully compensated for the biomechanical changes of the cornea. No additional higher-order aberrations were induced and no aberrations such as coma or sphere developed by the 6-month follow-up.
“No optical higher-order aberrations are significantly changed nor additional aberrations induced that could reduce vision sharpness and contrast. Thus the preoperative and postoperative higher-order aberrations are identical,” Dr. Arbelaez said.
The overall re-treatment rate was less than 2%.
Mechanism of action
According to Dr. Arbelaez, the aspheric ablation profile of the ORK-CAM and the aberration-free ablation profile work in tandem to garner these accurate results.
The aspheric ablation profile is capable of compensating for biomechanical factors in the cornea that might otherwise alter the surgical outcomes.
“[It] ensures that induced aberrations through biomechanical influences are compensated. Such influences include the microkeratome cut, tissue removal and thinning of the cornea, as well as varying energy losses depending on the corneal curvature during laser correction,” she said.
The aberration-free profile acts on mathematical and statistical evidence showing certain higher-order aberrations to have a positive influence on the final outcomes of an aspherical ablation.
“Physically, a clear correlation between an aspheric corneal line-shape function and higher-order spherical aberration terms exist. Hence, it is possible to generate an asphere out of given spherocylindrical-correction data using a well-defined and certain amount of higher-order aberrations,” Dr. Arbelaez said.
“Schwind-CAM aberration-free profiles balance other sources of aberration, reducing the refractive power by means of modulating the corneal radii of curvature according to the planned refractive correction but without introducing optical wavefront aberrations resulting in no induction of higher-order aberrations,” she said.
The treatment is most effective in patients with a visual acuity of 20/20 or better or in patients whose sight is unaffected by existing higher-order aberrations. If higher-order aberrations hinder vision, wavefront guided treatments should be employed rather than the aberration-free profile, Dr. Arbelaez said.
For more information:
- Maria C. Arbelaez, MD, can be reached at P.O. Box 938, P.C. 117, Wadi al Kabir, Muscat 117, Oman; +968-2469-1414; fax: +968-2460-1212; e-mail: drmaria@omantel.net.om. She has no financial interest in any of the products mentioned in this article.
- Schwind eye-tech solutions can be reached at Mainparkstr. 6-10, D-63801 Kleinostheim, Germany; +49-6027-508-164; fax: +49-6027-508-208; e-mail: info@eye-tech-solutions.com; Web site: www.eye-tech-solutions.com.
- Jared Schultz is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses geographically on Europe and the Asia-Pacific region.