Early multifocal ablation trial shows enhanced visual acuity, surgeon says

SEATTLE — In early results, all participants in an ongoing clinical trial of multifocal ablations have shown visual acuity improvement, according to an investigator.

Follow-up is brief and patients are few to date, but results of the U.S. clinical trial using the Visx Star S4 laser (Advanced Medical Optics) to create multifocal ablations for presbyopia correction are promising, said Colman R. Kraff, MD.

During the ASCRS Summer Refractive Congress here, Dr. Kraff described the Visx technology’s multifocal treatment design. A variable-spot, scanning, wavefront-guided technology is used to create the subtle ablation pattern to provide near and distance vision.

In the bilateral feasibility study for Food and Drug Administration premarket approval, the dominant eye receives a standard CustomVue treatment, and the nondominant eye receives the CustomVue treatment combined with the investigational presbyopic component, Dr. Kraff explained.

“Early postoperative results show positive outcomes,” he said. “Uncorrected distance vision, intermediate vision and near acuity in the multifocal eye has improved in all subjects. Multifocal eyes achieved 20/40 or better uncorrected near acuity in all five subjects.”

In the presbyopic correction, the central zone is steepened for near vision and the peripheral cornea is targeted for distance vision.

“We do what is called a pupil-size-dependent central zone,” Dr. Kraff said. “The peripheral zone, combined with the LASIK flap, produces an aspheric surface that expands the depth of focus.”

Iris registration is an important component for the presbyopic treatment because the multifocal ablation is pupil-dependent, he said.

“It is critical that we use iris registration to really accurately place the treatment over the pupil centroid,” Dr. Kraff said.

To date, five patients have been evaluated at the 3-month follow-up point.

“If you’re asking why it’s taken so long — almost a year for us to recruit five patients — it is because this is a unique clinical FDA trial with respect to multifocality,” Dr. Kraff said. He said the entry criteria are exacting and the postoperative evaluations are extensive, so recruitment has been a challenge.

“As many of you know, the quality of vision with a multifocal lens, especially patients who have any significant astigmatism, can be quite poor,” he said. “If patients answer in the preoperative questionnaire that they do not like the vision or certain levels of vision with a multifocal contact lens, they are rejected from the study. So the majority of the patients that we screened through this process have been eliminated based on these rigorous FDA criteria.”

Dr. Kraff presented a case study of one patient in the study, a 43-year-old man with preoperative uncorrected distance visual acuity of 20/60 and near visual acuity of 20/100 in the eye that received the multifocal correction. At the 3-month postoperative follow-up visit, he had uncorrected 20/60 distance vision, 20/20 intermediate vision and 20/60 near visual acuity.

Dr. Kraff said the investigation centers are continuing to enroll patients for this trial.