WaveScan-Guided Technology Achieves Positive Outcomes
Patient Satisfaction Increases
Refractive Surgery Quarterly -2006
BY COLMAN R. KRAFF, MD
Preliminary data of a feasibility study on aspheric ablations in patients with low hyperopia for presbyopia illustrate exciting results for refractive surgery. In a clinical trial, my colleagues and I used aspheric ablation profiles generated by variable spot scanning (VSS) technology to create subtle ablation shape changes to a patient’s wavefront map.
Dominant eyes received VISX CustomVue (Advanced Medical Optics, Inc.) hyperopic treatments targeted for emmetropia. Nondominant eyes received CustomVue hyperopic treatments concomitant with the investigational VISX presbyopic shape. The central zone was steepened to provide near vision, and the peripheral zone was targeted for distance vision.
In a typical patient with +2 hyperopia for a distance eye, an ablation profi le reveals a change in shape due to aspheric treatment.
Patients treated preoperatively and postoperatively achieve a tight volumetric point spread function through all ranges of vision from a distance of –2 to +2 postoperatively, according to our observations of aspheric, nondominant eyes.
Iris registration
Iris registration is an important component of presbyopia treatment. Proper registration of wavefront-guided ablation and proper placement of the pupil size-dependent central zone relative to the pupil centroid (pupil centroid shift compensation) are also important. The study additionally incorporated variability and the size of the aspheric treatment, or the size of the near adjustment based on pupil size. In the future, as aspheric ablations for presbyopia become commercially available, iris registration will be critical. Optimal results with the treatment will be further achieved with active intraoperative iris registration and re-registration.
Iris images from WaveScan and the VISX Star S4 laser show the pupil centroid shifts with different lighting conditions, as the pupil changes size. Iris registration ensures proper placement of add zone rotationally and with respect to pupil centroid shifts.
Clinical trial
Two United States centers participated in the clinical trial, and 20 patients were treated. Three-month follow-up data are available on 16 patients; 6-month follow-up data are available on 11 patients; and 9-month follow-up data is available on eight patients.
Patient age ranged from 41 to 57 years. The patients had low degrees of hyperopia, and 70% of the participants were men. Patients had low levels of cylinder in nondominant eyes, and the mean sphere of nondominant eyes was 1.5 D, with a range of +0.25 D to +2.5 D.
Preoperatively, no patients had 20/20 or better uncorrected distance vision in nondominant eyes. Six months after receiving Custom- Vue hyperopic treatments concomitant with the investigational VISX presbyopic shape, however, 73% of patients had 20/20 or better vision, 100% had 20/25 or better and 100% had 20/40 or better vision.
Results were similar with intermediate vision. No patients had 20/20 or better uncorrected intermediate vision preoperatively. At 6 months, 64% of patients had 20/20 or better vision, 100% had 20/25 or better and 100% had 20/40 or better vision.
Near vision data on the eyes treated with aspheric ablations were also encouraging. Preoperatively, 5% of patients had uncorrected near vision of J1 or better. At 6 months follow-up, 100% of eyes achieved near vision of J1 or better.
Binocular vision data
Signifi cant vision improvement was observed in binocular vision, as well. Preoperatively, no patients had uncorrected binocular distance vision of 20/20 or better; however, at 6 months, 100% of patients had 20/20 or better vision.
Patients with 20/20 or better uncorrected binocular intermediate vision rose from 5% preoperatively to 73% at six months postoperatively.
Results also showed binocular near vision improvement. At 6 months follow-up, 100% of eyes achieved 20/20 or better vision.
In addition, at 3- and 6-month follow-ups, no eyes lost more than two lines of best corrected visual acuity at distance, intermediate or near in the aspheric or monofocal eye, as expected.
Patient satisfaction
Data also revealed improved patient satisfaction. At 3 and 6 months, patient satisfaction with distance vision was 75% and 73%, respectively, and satisfaction with near vision was 63% and 73%, respectively. Patient satisfaction would possibly further improve with bilateral treatment.
In conclusion, early postoperative results at 3 and 6 months show positive outcomes with uncorrected distance, intermediate and near visual acuity in all eyes treated with aspheric ablation. The aspheric eyes achieved J1 or better in uncorrected near vision in 100% of patients at six months. Binocular uncorrected near visual acuity was excellent, with 100% of patients achieving J1 or better vision (Figure). Treatment appears to be safe, and further follow-up is ongoing.