The value of Femtosecond Laser Assisted Intrastromal Astigmatic Keratotomy in correction of astigmatism during Femtosecond Laser Assisted Cataract Surgery

Abstract

Astigmatism (> 0.5 diopters) is a commonly encountered refractive error, accounting for about 13 % of the refractive errors of the human eye. It is estimated that 15% to 29% of patients presenting for cataract surgery have more than 1.50 D of corneal astigmatism. As little as 0.50 to 0.75 D of uncorrected cylinder after cataract surgery can leave a patient with visual disturbances including blur, halos, and ghosting. Furthermore, in patients with multi-focal IOLs, even small amounts of residual astigmatism may reduce visual acuity noticeably, especially at near. Aside from glasses or contact lenses, treatment options for patients with cataracts who have preexisting corneal astigmatism include excimer laser refractive procedures; astigmatic keratotomy (AK), limbal or, corneal-relaxing incisions; and toric IOLs. Corneal or limbal relaxing incisions can be used in combination with monofocal, toric, or presbyopia-correcting IOLs at the time of cataract surgery. In astigmatic keratotomy, incisions can be limbal, arcuate, or transverse and are traditionally performed free-hand or with a mechanized keratome. The instruments used for astigmatic keratotomy are front cutting diamond blades and mechanized trephines, which can lead to corneal perforations, irregular astigmatism, undercorrections and worsening of the pre-existing astigmatism. Femtosecond laser technology offers the ability to control the desired shape, length, radius and depth of incisions in astigmatic keratotomy. Multiple studies have found femtosecond-assisted laser arcuate keratotomy to have enhanced predictability and a reduced rate of complications.