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Lenticule extraction safe, effective at 6 months
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NEW ORLEANS — Lenticule extraction with a femtosecond laser was shown to be safe and effective, with results improving as the learning curve is overcome, a presenter said at the American Academy of Ophthalmology meeting.
"We believe that this prospective study shows FLEX (femtosecond lenticule extraction) to be a safe procedure and effective," Marcus Blum, MD, said at an event sponsored by Carl Zeiss Meditec. "The refractive outcome is acceptable for all patients and is becoming better."
Dr. Blum presented 6-month follow-up data on the first 45 eyes treated with the technique, which was first presented at the AAO annual meeting in 2006.
"We remove the intracorneal lenticule to adjust the refractive properties of the eye so we actually have tissue removal instead of tissue ablation, and the whole success depends on the precision of the cut," Dr. Blum said. This study was conducted using the VisuMax femtosecond system (Carl Zeiss Meditec).
The study showed that none of the patients lost two or more lines and only one lost one line after 6 months, he said, adding that 40% of patients gained one line and 14% gained two lines.
Refractively, 90% of patients were within ±1 D, but the 6-month results are not as good as the 3-month results, Dr. Blum said. When the researchers split the study group into the first 20 patients and the last 25 patients, the first 20 showed a slight shift toward hyperopia.
At 6 months, the uncorrected visual acuity in two-thirds of the patients was 20/20 or better and one patient was 20/40, he said. He added that there were no adverse effects or complications, but one patient had mild haze 6-months postoperatively.
"As you see, we are getting better. So we do have a learning curve," Dr. Blum said. He added that stability up to now is good, but predictability analysis showed slight overcorrections in less myopic patients.
The procedure consists of four steps: processing the bottom or back of the lenticule; processing the front side of the lenticule at a depth of 120 µm to 160 µm, which overlaps the lenticule; making a side cut; and lifting the flap to remove the lenticule.
The lenticule thickness was originally targeted at 25 µm, but Dr. Blum said they are now creating 15-µm lenticules. Diameter is determined by pupil size, he added, and the studied eyes were between 6 mm and 7.3 mm. Overlap between lenticule and flap averaged about 4.5 mm, and the governing ethics committee required a 300-µm stromal bed.
The study included myopes with up to 6 D of astigmatism, with an average of 4.5 D, and targeted refraction at –0.75 D, Dr. Blum said.
"It's a new approach in refractive surgery," he said.