Femtosecond laser allows one-step LASIK in postPK eyes

Chicago-IntraLASIK as a one-step procedure is safe and effective for correction of ametropia after penetrating keratoplasty (PK), although the best refractive results may be achieved in eyes with only mild-to-moderate astigmatism, said Irina S. Barequet, MD, at the refractive surgery subspecialty day meeting sponsored by the International Society of Refractive Surgery of the American Academy of Ophthalmology.

Dr. Barequet, lecturer, department of ophthalmology, Tel Aviv University, Israel, presented results from a retrospective review of outcomes at 2 months postIntraLASIK in a group of ten eyes that had undergone PK an average of 47.2 months earlier. Prior to IntraLASIK, mean astigmatism for the group was –6.5 D, three eyes were hypermetropic, and four eyes were myopic.

Limits of the flap were planned to be within the corneal graft margins. Flap diameters ranged from 7.6 to 7.7 mm and measured 90 to 100 µm in thickness. The ablation was performed with a Bausch & Lomb laser at an optical zone ranging from 4.5 to 6 mm at an average depth of 102 µm.

There were no intraoperative complications and no graft rejections or corneal neovascularization developed postoperatively. The procedure had a safety index of 1.14 and uncorrected visual acuity was improved in 78% of eyes with mean values improving from 0.08 preoperatively to 0.29 at 2 months. Spherical error was reduced by 94% and SE by 78% as the mean reduction in cylinder was only 45%.

“The femtosecond laser microkeratome allows controlled flap creation within the graft margins and avoids involvement of the graft host junction as well as creation of a lamellar cut in a thin host area. Those benefits probably provide immunological and mechanical advantages and reduce the effect of the flap creation on astigmatism to allow for a one-step versus staged flap creation-ablation procedure,” said Dr. Barequet.