Femtosecond intrastromal presbyopia correction offers near visual acuity gain, stability while preserving the corneal surface

The noninvasive procedure yielded strong gains in uncorrected near visual acuity, and more than 70% of patients were satisfied with the results.

Issue: May 25, 2012

A proprietary femtosecond laser-based intrastromal presbyopia correction procedure yielded positive visual outcomes and high patient satisfaction, a study found.

The procedure markedly improved uncorrected near visual acuity but reduced corrected distance visual acuity in about 7% of eyes.

Mike P. Holzer, MD, FEBO, and colleagues analyzed outcomes from the IntraCor procedure, which is performed exclusively with the Technolas 520F femtosecond laser (Technolas Perfect Vision).

Results showed stable postoperative visual outcomes, Prof. Holzer said.

“What we saw was that the refractive outcome was stable over time, which is good,” he said. “We also did not see any severe disease to the cornea, for example, ectasia, corneal thinning or severe scarring.”

The study was published in the Journal of Refractive Surgery.

Patients and methods

The prospective, multicenter clinical trial included 63 patients with a median age of 54 years who underwent the IntraCor procedure in the nondominant eye. Treatment time ranged from 15 to 20 seconds.

Uncorrected and corrected distance visual acuity, uncorrected and corrected near visual acuity and distance-corrected near visual acuity were assessed preoperatively and 1 day, 1 week, and 1, 3, 6 and 12 months postoperatively.

Slit lamp examinations, digital photography and corneal topography were performed before surgery and at 3, 6 and 12 months after surgery. A questionnaire was used to measure patient satisfaction.

Visual acuity, satisfaction

Study results showed that median logMAR uncorrected distance visual acuity of 0.1 was unchanged at 12 months. In addition, 43.1% of eyes gained one or more lines of uncorrected distance visual acuity, 24.1% were unchanged, and 32.7% of eyes lost one or more lines. The changes were not statistically significant.

All eyes attained corrected distance visual acuity of 20/40 or better; 25% of eyes gained one to three lines. However, 21.4% of eyes lost one line and 7.1% lost two lines of corrected distance visual acuity.

“The reason is that you increase the depth of focus with this procedure and you change the spherical aberrations,” Prof. Holzer said. “However, that was only in the nondominant eye, so the binocular distance visual acuity was still good.”

Median logMAR uncorrected near visual acuity improved from 0.7 preoperatively to 0.2 at 1 year; 70.7% of eyes attained Snellen visual acuity of 20/40 or better. All eyes gained uncorrected near visual acuity; 3.4% of eyes improved nine lines.

Median maximum axial curvature within the central 4-mm zone of treated corneas increased from 44.6 D preoperatively to 45.30 D at 12 months postoperatively; the increase was statistically significant (P < .001).

Results showed that 71.4% of patients were satisfied with visual outcomes; 19.6% were dissatisfied and 9% were uncertain. No adverse events were reported.

Clinical observations

Dissection of stromal fibers during the IntraCor procedure ultimately steepens the central cornea, whereas LASIK involves ablation of the cornea, Prof. Holzer said.

“The advantage of the femtosecond laser is that you can focus the laser beam at any depth of the cornea and do your treatment there,” he said. “The difference is also that with LASIK and the excimer laser, you ablate corneal tissue. That means you really make the cornea thinner. With the femtosecond laser, you do not really remove corneal tissue. The corneal thickness is the same later on.”

The procedure is somewhat akin to presbyLASIK in terms of central corneal steepening, Prof. Holzer said. However, IntraCor is not a monovision procedure, even though it is performed in one eye. Bilateral or second-eye IntraCor surgery is not recommended, except in a few select cases, Prof. Holzer said. – by Matt Hasson

Reference:

Holzer MP, Knorz MC, Tomalla M, Neuhann TM, Auffarth GU. Intrastromal femtosecond laser presbyopia correction: 1-year results of a multicenter study. J Refract Surg. 2012;28(3):182-188.

For more information:

Mike P. Holzer, MD, FEBO, can be reached at International Vision Correction Research Centre, University of Heidelberg, Department of Ophthalmology, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; 49-6221-566695; fax: 49-6221-566607; email: mike.holzer@med.uni-heidelberg.de.
Disclosure: Prof. Holzer receives consulting fees and lecture honoraria from Technolas Perfect Vision.