• Written By: Elizabeth M. Hofmeister, MD
    Refractive Mgmt/Intervention

    This prospective study assessed the effectiveness of a new ray-tracing algorithm for creating individualized LASIK ablation profiles to treat moderate to high myopic astigmatism. The results, which were reported in January in the Journal of Cataract & Refractive Surgery, demonstrate that ray tracing-guided LASIK is safe, efficacious and predictable for this condition.

    Clinical outcomes three months postoperatively were equal to or better than with wavefront-guided LASIK. While larger studies are needed, ray tracing-guided LASIK shows great promise for moderate to high myopic astigmatism and offers the potential of highly individualized corneal refractive treatment.

    The study's authors say that the newly developed algorithm uses data from every optically relevant structure in the eye and calculates an individual eye model from which a custom ablation profile is derived. Use of the algorithm eliminates the need for a nomogram.

    Seventy-one patients (127 eyes) at three centers in Europe were enrolled in the study. They had manifest refraction sphere ranging from 0.50 to -10.25 D (mean, -5.92 D) and/or astigmatism ranging from 0.00 to -4.50 D. The intended outcome was plano in most eyes, undercorrection of 0.50 D in one eye and undercorrection of 0.25 D in two eyes.

    Of the 111 eyes observed three months postoperatively, 93 (83.8 percent) had an uncorrected distance visual acuity of 20/20 or better. The mean manifest refraction spherical equivalent (MRSE) in all eyes was 0.03 ± 0.30 D. MRSE was within ± 0.50 D in 97 eyes (87.4 percent) and within ± 1.00 D in 107 (96.4 percent). No eye lost two or more lines of corrected distance visual acuity.