WaveScan-Guided Hyperopic Multifocal Ablations
Preliminary results from the clinical trial show promise for hyperopic presbyopes.
Cataract and Refractive Surgery Today - Issue: October 2005
BY COLMAN R. KRAFF, MD
Hyperopic presbyopic laser vision correction with the Star S4 excimer laser (VISX, Incorporated, Santa Clara, CA) is currently undergoing feasibility studies with the FDA and is available internationally. Mine is one of two clinics involved in this study. I have treated 10 patients with the procedure and am in the process of recruiting 10 more. My co-investigators and I currently have 3-month data on five patients.
STUDY PARAMETERS
The parameters of the trial are to correct 1.25 to 1.50D of presbyopia using the patented VISX multifocal ablation profile with the company’s Variable Spot Scanning technology. The system is designed to induce a subtle change in the ablation shape of the subject’s wavefront map. Patients’ dominant eyes receive a CustomVue hyperopic treatment targeted for emmetropia, and their nondominant eyes receive a CustomVue hyperopic treatment combined with the investigational VISX presbyopic shape. The treatment includes iris registration (see sidebar). We steepen the central zone to provide near vision and target the peripheral zone for distance. The combined effect produces an aspheric curve that expands patients’ depth of focus.
Although we counsel the patients to have realistic expectations about their outcomes, so far, those in this trial have been very happy. There is a very high level of patient satisfaction, and the treatment has worked particularly well in those with low-to-moderate hyper-opia with a limited amount of astigmatism. The patients in the trial are between 41 and 54 years old, and 67% of them are male.
THREE-MONTH RESULTS
Preoperatively, the patients’ nondominant eyes (which received the multifocal ablations) had on average 1.67 ± 0.47D (+1.00 to 2.50D) of sphere and 0.19D ± 0.17 (0 to 0.50D) of cylinder. By 3 months, all of these five eyes had 20/20 uncorrected distance vision, 80% had 20/20 uncorrected intermediate vision (Figure 1), and 100% of the eyes had 20/40 or better uncorrected near vision (Figure 2).
Perhaps more important are the binocular results. Preoperatively, no patient had binocular uncorrected distance vision of 20/20 or better, whereas all five achieved this target by 3 months postoperatively. Uncorrected binocular intermediate vision was less than 20/25 in all subjects preoperatively, but 80% achieved 20/16 or better by 3 months. The near vision results were similar: preoperatively, only one patient had uncorrected binocular acuity of 20/40 or better, compared with all of the patients by 3 months postoperatively.
Also importantly, no eyes, receiving multifocal or CustomVue, lost BSCVA at distance, intermediate, or near by 3 months (five subjects).
DISCUSSION
As enrollment and follow-up for this trial continue, I am cautiously optimistic about the ability of WaveScan-Guided Hyperopic Multifocal Ablation to serve the presbyopic hyperopic population, although the results of the clinical trials are too preliminary to draw any firm conclusions. I will say, however, that its shape is good and should only improve with continued use. Assuming that this procedure continues to show consistently good results, I think that some day it might benefit patients between the ages of 45 and 55 who have 0.50D to possibly 3.00D of hyperopia. Also, this type of treatment may offer certain advantages over lenticular correction, such as being less invasive, which many riskadverse patients will likely appreciate. Hyperopic laser vision correction would also be more cost effective for patients than lenticular surgery, because it would not require a surgery center or a phaco machine. For the surgeon, its technique is the same as LASIK’s, but with different software. In general, hyperopic laser vision correction may be a viable option for patients who have low levels of hyperopia, a clear crystalline lens, and very little astigmatism, as an alternative to their glasses or readers. However, patient selection with this procedure will be very important.
Colman Kraff, MD, is Director of Refractive Surgery at the Kraff Eye Institute in Chicago, Illinois. He is a clinical investigator for WaveScan-Guided Hyperopic Multifocal Ablation, but states that he holds no financial interest in VISX Incorporated or its products. Dr. Kraff may be reached at (312) 444-1111; c.kraff@ix.netcom.com.