Intracor Shown Effective for Limited Patient Pool

By Linda Roach

While Intracor offers a fast and minimally-invasive approach for treating presbyopia with the femtosecond laser, it is appropriate only for low hyperopes, who might lose up to two lines of best-corrected distance acuity in the treated eye, German researchers report.

Patients in the group’s study gained as much as nine lines of near visual acuity from the incisionless femtosecond laser procedure. However, 7.1 percent of treated eyes lost two lines of uncorrected distance visual acuity (UCDVA).¹

“At the beginning, there was hope that this was a procedure that you could offer to many patients coming into the office. Now it is clear that we really need to remember that Intracor is just for a very specific group of patients,” said Professor Mike P. Holzer, MD, the lead author of the paper.

He is vice chairman of ophthalmology at Ruprecht-Karls-University in Heidelberg, Germany, and director of refractive surgery at the International Vision Correction Research Centre there.

Twenty Seconds of Pulses

Intracor is a 15- to 20-second femtosecond laser procedure developed in 2007 by Colombian surgeon Luis A. Ruiz, MD, of Centro Oftalmológico Colombiano in Bogotá. It reshapes the cornea by delivering rings of laser spots within the cornea.

The basic pattern is a series of femto-disruptive cylindrical rings that begin within the posterior stroma, at a variable distance from Descemet’s membrane. The rings spiral anteriorly through the mid-stroma until reaching a predetermined, fixed distance beneath Bowman’s layer.

The treatment is a proprietary application for the laser formerly known as Femtec, now renamed Victus (Bausch + Lomb, Technolas Perfect Vision). It has CE Mark approval, although approved indications vary by country.

Biomechanical Effects on the Cornea

The treated tissue alters corneal biomechanics, steepening the anterior corneal surface and creating a hyperprolate shape that increases the eye’s depth of focus and reduces spherical aberrations.

Cavitation bubbles interfere with the patient’s vision for 1.5 to 2 hours after the procedure, and most of the improvement in UCVA occurs during the first month after treatment, Dr. Ruiz reported in 2009² and the Heidelberg group's studies later confirmed.

In the latest study, 70.7 percent of patients who received unilateral Intracor had Snellen uncorrected near visual acuity (UCNVA) of 20/40 or better 12 months after surgery, compared with 3.2 percent preoperatively (P < 0.01). The median gain in UCNVA was four lines (logMAR), with 3.4 percent gaining nine lines (P < 0.01). There were no adverse events. Postop visual acuities were stable during follow-up.

Prior to undergoing Intracor treatment, study participants had hyperopia between 0.50 and 1.25 D, cylinder less than or equal to 0.50 D, corrected distance visual acuity (CDVA) of at least 20/25, a minimum near add of +2.0 D at 40-cm distance and Scheimpflug corneal thickness of at least 500 microns.

Drawbacks in the Data

The data also highlight the procedure’s limitations. The paper reported that:

In addition to 7.1 percent of treated eyes losing two lines of UCDVA, another 21.4 percent lost one line.
32.8 percent reported noticeable postoperative vision problems in dim light, nearly double the preoperative figure of 17.2 percent.
19.6 percent were unsatisfied with the procedure’s outcome, and 12.3 percent said they would not undergo the treatment if they could choose again.
16 percent said they would not recommend Intracor to a relative or friend.

Not a Cure-all for Presbyopia

The study supports the conclusion that Intracor should not be viewed as a universally applicable treatment for presbyopia, Dr. Holzer said. But he said his clinic’s experience with about 350 Intracor patients has shown that a small subset of patients can really benefit.

“For a specific patient group, this is a good alternative with quick recovery time, but it will not be like a multifocal lens that you can offer to a large number of presbyopes,” Prof. Holzer said.

His experience has shown that the right type of presbyope, one who is well-informed about what to expect, will be happy with the outcome, he said. He suggested that, because the potential patient base is small, Intracor probably will find its niche at large referral refractive surgery practices such as his.

Presbyopes Who Can Benefit from Intracor

Dr. Holzer recommends Intracor only for patients with between 0.50 D and 1.25 D of hyperopia, because they usually don’t wear eyeglasses and are accustomed to a slight blur at distance. “They tell us they see well at distance,” he said. For this patient group, there are also only limited alternative treatments available, he noted.

“Start with the patient who sees 20/32 to 20/40. These patients typically do not use glasses for distance,” he said. “The laser treatment reduces their hyperopia about one-half of a diopter, and then the change in the corneal shape narrows their depth of focus. If you test their acuity, you will realize they lost maybe one line of best-corrected distance acuity, but because they didn’t use glasses pre-op they don’t realize it.”

Like all presbyopic treatments, the informed consent process is paramount, Dr. Holzer said. “What’s really crucial is not to promise too much. Show them the near acuity chart and the size of type they will be able to read without eyeglasses. Tell patients honestly what they can expect and what they cannot expect. Then you will have very satisfied patients.”

References

1. 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.

2. Ruiz LA, Cepeda LM, Fuentes VC. Intrastromal correction of presbyopia using a femtosecond laser system. J Refract Surg. 2009;25(10):847-854.

Financial Interests

Dr. Holzer receives consulting fees, travel funding and grant support from Technolas Perfect Vision.