Intrastromal approach closes in on near vision

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Intrastromal femtosecond laser treatment for presbyopia (INTRACOR, Bausch + Lomb/Technolas Perfect Vision) can significantly improve near vision and result in high satisfaction rates with patients.

By Cheryl Guttman Krader; Reviewed by Mike P. Holzer, MD

Heidelberg, Germany-Corneal intrastromal femtosecond laser treatment for presbyopia can be an effective method for improving near vision. Careful patient selection and informed consent are important criteria, however.

Mike P. Holzer, MD, director of refractive surgery, International Vision Correction Research Centre, University of Heidelberg, Germany, highlighted outcomes from 25 patients with hyperopia and presbyopia who had the intrastromal treatment (INTRACOR), Bausch + Lomb/Technolas Perfect Vision) performed in the non-dominant eye; 23 patients had follow-up at 3 years. He also presented results from a prospective study of 17 patients who were treated bilaterally.

Patients treated in the non-dominant eye only had an average gain of 4 to 5 lines in uncorrected near vision (UNVA) that was stable during follow-up. However, the level of improvement varied from 1 to 8 lines.

In addition, most treated eyes lost 1 or 2 lines of uncorrected and corrected distance visual acuity (UDVA and CDVA), and contrast sensitivity decreased slightly as well. Bilateral treatment resulted in more consistent UNVA gains.

“Patients really like this minimally invasive procedure that is fast, painless, and has a rapid, comfortable postoperative recovery,” Dr. Holzer said.

“However, they need to be given a detailed informed consent so they have proper expectations and understand the limitations of the procedure, which include the fact that there are no or limited re-treatment possibilities,” he said. “In addition, further research is needed to improve the predictability of the outcomes and to understand the changes it causes in corneal biomechanics.”

The intrastromal femtosecond laser treatment received the CE mark in 2009, but is not FDA approved. It involves use of a proprietary femtosecond laser algorithm (Victus, Bausch + Lomb/Technolas Perfect Vision) to create five concentric rings in the central cornea. The treatment results in a central corneal steepening that averages about 1 D, induces some negative asphericity, and provides increased depth of focus. Together, these effects account for the improvement in near vision.

Candidates for the procedure should have a near add requirement >+1.5 D, spherical equivalent of +0.5 to +1.25 D, subjective astigmatism ≤0.5 D, and topographic astigmatism ≤1.5 D.

“It is important to select patients who fall within this very narrow range of hyperopia,” Dr. Holzer said. “We recommend doing a cycloplegic refraction as well as defocus testing for preoperative screening.”

Study outcomes

The analyses of the patients who had unilateral treatment showed mean UNVA increased significantly from 20/100 at baseline to 20/25 at 3 years, and there was a similar significant improvement in distance-corrected near visual acuity. About 80% of patients did not need reading glasses, and 90% said they would undergo the procedure again.

Although the treated eyes had an average 1- to 2-line loss of CDVA, CDVA at 3 years was still 20/25 or better in all patients.

Results from patient questionnaires showed the patients were not bothered by glare or halos, but they had mild-to-moderate difficulty with reading in dim light and mild difficulty driving at night.

“Glare and halos seem to be less of an issue after this procedure than for patients with a presbyopia-correcting multifocal IOL [implanted],” Dr. Holzer said. “However, it seems that for patients to enjoy the benefits of the intrastromal procedure, good lighting conditions are needed.”

Pros, cons bilateral treatment

For patients treated bilaterally, data were available from follow-up of between 4 and 8 months, and their results were compared with a matched group of 17 patients who had unilateral treatment. UNVA was 20/32 or better in 90% of the patients treated bilaterally compared with 60% of the unilateral group. UDVA outcomes were similar in the two groups, and about two-thirds of patients in both groups had a 1-line loss of CDVA. One patient (6%) in the bilateral group lost 2 lines of CDVA.

Mike P. Holzer, MD

E: mike.holzer@med.uni-heidelberg.de

Dr. Holzer receives consulting fees from Bausch + Lomb and Technolas Perfect Vision. This article is adapted from Dr. Holzer’s presentation during Refractive Surgery 2012 at the annual meeting of the American Academy of Ophthalmology.