Femtosecond - Assisted Astigmatic Keratotomy

T he treatment of moderate to high astigmatism is challenging for the refractive surgeon. Even in experienced hands, 40% of patients who undergo penetrating keratoplasty (PKP) are left with more than 4.00 D of astigmatism.1 Spectacles, contact lenses, excimer laser ablation, toric IOLs, and tissue-relaxing procedures have been used for a long time in the treatment of preexisting and postsurgical corneal astigmatism.2-4 We propose the use of femtosecond-assisted astigmatic keratotomy (AK) for treatment of moderate to high astigmatism. Because AK is a simple and effective technique to manage astigmatism,5 it is the most commonly used surgical treatment for post-PKP astigmatism.6 The technique is similar to limbal relaxing incisions; the corneal incisions perpendicular to the steep meridian produce a flattening effect along the axis centered over the incision (Figure 1).7 Likewise, the incisions induce steepening at the nonincised meridian 90o away. This coupling effect avoids significant change in the spherical equivalent refraction.7,8 AK can be performed with a freehand technique, but mechanized devices such as the Hanna arcitome (Moria, Antony, France) allow more reproducible results.9 Nevertheless, corneal perforation, wound dehiscence, and the decreased efficacy that result from such events lessen the reliability of these devices.2,7 Surgeons have described use of the femtosecond laser as an alternative to perform AK.10-12 Combining the predictability of the femtosecond laser with the simplicity and effectiveness of AK enhances reproducibility and improves accuracy and safety.10,11 In this article, we demonstrate our surgical technique for femtosecond-assisted AK in a case with high againstthe-rule corneal astigmatism after PKP. Femtosecond-Assisted Astigmatic Keratotomy