Myopia with astigmatism treated with high-speed excimer laser

July 25, 2012
Lynda Charters

Myopia with astigmatism can be treated by performing myopic LASIK and LASEK using a high-speed excimer laser (Schwind Amaris 750S).

Muscat, Oman-Myopia with astigmatism can be safely, effectively, and predictably treated by performing myopic LASIK and LASEK using a high-speed excimer laser (Schwind Amaris 750S). The results of the two treatments were very similar in the refractive outcomes and visual acuity, according to Maria C. Arbelaez, MD.

Dr. Arbelaez, medical director, Muscat Eye Laser Center, Muscat, Sultanate of Oman, conducted a retrospective, non-comparative case series study that included 225 eyes that underwent LASIK and 82 eyes that underwent LASEK. She and her co-authors measured the manifest refraction, visual acuity, and corneal higher-order aberrations preoperatively and 6 months postoperatively. All eyes were targeted for emmetropia. The preoperative mesopic contrast sensitivity was measured in 92 eyes that underwent LASIK.

She reported that data were available for 190 eyes in the LASIK group and for 60 eyes treated with LASEK that were examined at the 6-month time point.

Preoperatively, the spherical equivalent in the LASIK group ranged from –0.5 to –9.5 D (mean –3.29 ± 1.72 D), the sphere ranged from –8.75 to 0.00 D (mean –2.96 ± 1.71 D), and the cylinder ranged from –4.75 to 0 D (mean –0.67 ± 0.64 D).

Dr. Arbelaez reported that at the 6-month examination the spherical equivalent was from –0.5 to +0.13 D (mean –0.09 ± 0.13 D), the sphere was from ­0.50 to +0.25 D (mean –0.04 ± 0.12 D), and cylinder was from –0.75 to 0 D (mean –0.10 ± 0.15 D).

In the 82 eyes in the LASEK group, the mean preoperative spherical equivalent ranged from 1.00 to –8.75 D (mean –3.72 ± 1.75 D), the sphere ranged from –8.75 to –0.75 D (mean –3.39 ± 1.77 D), and the cylinder ranged from –2 to 0 D (mean –0.67 ± 0.64 D). In the 60 eyes that completed the 6-month examination, the results were almost identical to those in the LASIK group.

The results indicated that both groups of patients fared extremely well. In commenting on the results, Dr. Arbelaez showed scattergrams for the LASIK and LASEK groups.

“The scattergrams showed comparable values with low scatter in both groups at 6 months,” she said.

In both groups, 93% of the eyes were within ± 0.25 D of the intended correction.

She also pointed out that the cylinder correction was excellent in both groups.

At the 6-month examination, no eyes in either group lost more than one line of best spectacle-corrected visual acuity. Both the uncorrected visual acuity and the best-corrected visual acuity were similar in both groups. The stability of the correction was also found to be similar between the two procedures.

Corneal analysis showed that there was almost no change in the corneal higher-order aberrations in the two groups.

The LASIK group showed a gain in contrast sensitivity. No such data were collected in the LASEK group.

“We found the 750-Hz laser procedure to be safe and predictable,” Dr. Arbelaez concluded. “At the 6-month evaluation there were no significant differences between the two groups in refractive outcomes and visual acuity.”

Dr. Arbelaez reported a financial interest in this technology and receives travel expenses from Schwind. This procedure has not received FDA approval.

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