Most patients treated with the three FDA-approved wavefront-guided systems report improvements in glare, halos and quality of night vision.
By Nicole Nader
Patients in the clinical trials of the Bausch & Lomb and Visx wavefront-guided custom ablation systems report higher satisfaction with their postoperative nighttime visual results than their preoperative night vision, according to investigators of all three systems.
Surveys of patients in the clinical trials for Food and Drug Administration approval of the Bausch & Lomb Zyoptix and Visx CustomVue wavefront-guided customized ablation systems all found decreases in many patients' night vision problems, according to investigators.
Researchers found decreases from preoperative levels in patients' complaints related to poor night vision with all three systems, as well as increases in overall satisfaction with vision.
"The overall satisfaction of patients' visual outcome appears to be higher when compared to my standard LASIK patients," said Colman R. Kraff, MD, a lead investigator in the Visx CustomVue clinical trial.
"Issues relating to night vision really went against the grain of traditional thought about LASIK," Dr. Durrie said. "People say, 'LASIK causes dryness, glare and halos at night.' But these patients told us that wavefront-guided LASIK did not induce significantly more glare and halo."
"Patients said that their night vision improved, and they had absolutely no complaints postop," agreed Stephen G. Slade, MD, medical monitor of the clinical trial for Bausch & Lomb's Zyoptix system.
"This new data gives surgeons the ability to say with much more confidence that the likelihood of having significant problems with wavefront with respect to night vision, glare and halos is potentially minimized," Dr. Kraff said.
Taken together, more than 1,100 eyes were treated in the phase 3 clinical trials of the three customized ablation systems. Researchers distributed questionnaires to more than 500 patients in the three trials. Among other responses, patients subjectively graded their preoperative and postoperative experience of glare, halo and their quality of night vision. Questionnaire results from patients treated with each system are reviewed in this article.
Large pupil patients happy
Similar responses were seen from patients in the Visx clinical trials.
Preoperatively, patients were asked about their satisfaction with their night vision when wearing correction; 65% of respondents said they were either satisfied or very satisfied.
At 6 months postoperatively, the patients were asked about their satisfaction without correction; at that time, 85% of respondents said that they were satisfied or very satisfied with their postoperative night vision without correction, Dr. Kraff noted.
Regarding night vision with glare, 81% of postoperative patients were satisfied or very satisfied, compared to 60% before surgery, he said.
Dr. Kraff noted that about the same percentage of patients in the Visx survey, 76%, said they experienced halos around lights "rarely or never" both before and after surgery, so there was no reported increase in this symptom.
Dr. Kraff noted that the improvement in night vision was also seen in people with large pupils treated with the Visx system.
"In the past, these patients have been the hardest to please," Dr. Kraff said. "People with larger pupils are often more dissatisfied with their nighttime vision. You would expect this group to have the largest complaints, but this was not the case. People with the largest pupils were the happiest with their nighttime vision. This was very surprising."
The questionnaire responses were analyzed in relation to preoperative pupil size. Patients were categorized into three groups: small pupils (6 mm or less), average-sized pupils (6.1 mm to 7.5 mm) and large pupils (greater than 7.5 mm).
Preoperatively, 69% of patients with small pupils and 65% of patients with average-sized pupils were satisfied or very satisfied with their night vision. Of patients with large pupils, 58% were satisfied or very satisfied with their preoperative night vision.
"After surgery, satisfaction jumped from 58% to 89% of large pupils who were happy with their night vision," Dr. Kraff said. Similarly, 87% of patients with small pupils and 83% of patients with average-sized pupils reported satisfaction with their night vision.
Similar outcomes occurred in regard to glare. In the largest pupil group, 81% reported satisfaction after surgery as compared with 51% preoperatively, Dr. Kraff said.
He attributed the high level of satisfaction in large-pupil patients to the variable spot scanning of the Visx system and the use of wavefront data to correct higher-order aberrations.
Improved contrast sensitivity
Patients in the Bausch & Lomb Zyoptix wavefront trials also answered questionnaires. According to company materials, about 40% of patients reported having better night driving vision 6 months postoperatively than they did before surgery.
Dr. Slade noted that in addition to the subjective survey results, clinical tests also seemed to confirm this improvement in night vision. While survey results on night vision are encouraging, he cautioned, they should not be equated with scientific findings.
"We had an improvement in contrast sensitivity (that) was statistically significant," Dr. Slade said. He said no other clinical study he is aware of has demonstrated a statistically significant improvement in contrast sensitivity by 2 units of measurement.
Improvement in contrast sensitivity can significantly improve a patient's night vision, Dr. Slade said.
"Patients are able to see lighter contrasts. They can see things that they didn't see before in a variety of low light settings," he explained.
According to Dr. Slade, contrast sensitivity correlates with aberrations in the eye. "Contrast sensitivity is one of the best measurements we have to determine the practical effect of aberrations on the eye," he said. "For instance, we will be able to objectively grade what 0.1 µm of spherical aberration means. Contrast sensitivity can show you how much aberration exists in a patient's eye."
For Your Information:
- Daniel S. Durrie, MD, can be reached at Durrie Vision, 5520 College Blvd., Suite 200, Overland Park, KS 66211; (913) 491-3737; fax: (913) 491-9650; e-mail: email@example.com.
- Stephen G. Slade, MD, can be reached at 3900 Essex Lane, Suite 101, Houston, TX 77027; (713) 626-5544; fax: (713) 626-7744; e-mail: firstname.lastname@example.org.
- Colman R. Kraff, MD, can be reached at Kraff Eye Institute, 25 E. Washington, Suite 606, Chicago, IL 60602; (312) 444-1111; (312) 444-1953; e-mail: email@example.com. Dr. Kraff is a paid consultant for Visx. He has no direct financial interest in the products discussed in this article.
- Bausch & Lomb, manufacturer of Zyoptix, can be reached at 1400 N. Goodman St., Rochester, NY 14609; (585) 338-5212; fax: (585) 338-0898; Web site: www.bausch.com. Visx Inc., manufacturer of CustomVue, can be reached at 3400 Central Expressway, Santa Clara, CA 95051-7122; (408) 733-2020; fax: (408) 773-7278.