Presbyopia-correcting procedure shows promising results
Intrastromal correction of presbyopia produced clear, statistically significant improvement in near vision and a slight improvement in distance vision.
The Clinic for Refractive and Ophthalmic Surgery in Duisburg, Germany, is the second study center in a clinical multicenter study for CE approval of intrastromal presbyopia correction with the Femtec femtosecond laser. The study is being performed under the direction of Gerd U. Auffarth, MD, and Mike P. Holzer, MD, University Eye Clinic Heidelberg, Germany.
As part of this clinical study, we performed intrastromal presbyopia and mild hyperopia correction using the Femtec femtosecond laser (Technolas Perfect Vision) under standardized, controlled conditions. This procedure was applied for the first time by Luis Antonio Ruiz, MD, in 2007 in Bogotá, Colombia.
The intraCOR procedure
Before intrastromal correction of presbyopia with the femtosecond laser, or intraCOR, we mark the first-order Purkinje reflex very precisely. The vacuum suction ring is then positioned according to this marking, using a centering cross. The mark then serves as the center of treatment. A low vacuum volume is applied to the suction ring to limit increasing IOP. Consequently, care must be taken that the suction ring does not tip, and the patient must not move during the docking procedure or during the brief treatment.
The intraCOR procedure for this treatment is performed in the stromal tissue of the cornea. The epithelium and the Descemet’s membrane are not touched or affected.
Patients with presbyopia and mild hyperopia up to +0.75 D are treated with five intrastromal, concentric ring cuts with the Femtec femtosecond laser. The procedure takes about 20 seconds.
In order to correct presbyopia with this procedure, the cornea is steepened centrally to increase refractive power. A new balance in corneal biomechanics results from this procedure. There is also an attendant myopic shift.
Corneal topography Scheimpflug camera comparison of preoperative and postoperative images reveals a change in refraction of about 2 D in the central corneal area.
There were 21 presbyopic patients (11 women, 10 men) with preop uncorrected visual acuity of +0.75 ± 0.19 D distance and 0.19 ± 0.09 D near vision in our first study group. Preop refraction for the sphere was +0.61 ± 0.46 D and –0.23 ± 0.25 D for the cylinder. The mean age of the patients was 53.8 ± 6.2 years. Follow-up controls were scheduled after 1 day, 1 week, 1 month, and 3, 6 and 12 months. Currently, all patients have undergone the 3-month postop control. Half-year results are already available for 15 of 21 patients.
The postop examination of uncorrected near vision using the Sloan chart showed that all study participants presented a clearly and statistically significant improvement. All patients could read better without correction postop than preop without correction; 42.6% of the treated patients showed a postop improvement of at least six logMAR lines.
The results of intraCOR were convincing. In our opinion, the procedure can be rated extremely safe. In some patients, there was a decrease of visual acuity in distance vision immediately postop because the bubble effect caused by the intrastromal tissue expansion was of optical relevance. Vision gradually recovered after only 1 week. After 3 months, improvement in visual acuity for distance vision could also be observed.
Examination of uncorrected distance vision using the Sloan chart showed a mild improvement in visual acuity in all patients. No significant change was found in the examination of best corrected visual acuity.
The intrastromal correction of presbyopia combined with mild hyperopia up to +0.75 D can be performed with the femtosecond laser safely and extremely effectively. All treated patients present postop with a clear, statistically significant improvement in near vision and a slight improvement in distance vision.
This procedure has almost no side effects. We are convinced that this possibility of intrastromal refractive correction points the way for the future and has the potential to make a lasting change, not only in the presbyopia market but also in the area of low ametropia.
- Mark Tomalla, MD, can be reached at Clinic Niederrhein, Fahrnerstr. 133-135, 47169 Duisburg, Germany; +49-203-5081711; fax: +49-203-5081713; e-mail: email@example.com; Web site: www.augenklinik-duisburg.de. Dr. Tomalla has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.