Visual and Optics Impact of Refractive Surgery

Refractive surgery includes interventions to correct refractive errors, using a medical device such as a laser or an implant (intraocular lenses) or surgical instruments. The study distinguishes corneal interventions, carried on the surface of the eye, and intraocular interventions, performed on the lens or in the anterior or posterior chamber of the eye. The number of procedures in refractive surgery is growing significantly. They seem to offer satisfactory visual results but a number of issues remains unresolved. In order to get emmetropia, refractive surgery corrects optical defects by decreasing aberrations of lower orders (ie spherical refractive error and astigmatism). This increases high-order aberrations (the most common is a bright halo on the edge of the image). The cutting of the flap to the surface of the cornea in the case of LASIK increases high-order aberrations, which have the effect of reducing post-surgical visual performance (ie visual acuity and contrast sensitivity) and can't be corrected by glasses, while the adaptation of contact lenses on a post-operative cornea is more complex. It is therefore necessary to limit these post-surgical aberrations and to identify their possible sources. Indeed, some authors have provided insight into the effects of some high-order aberrations, but the influence of several factors characterizing the preoperative eye on refractive surgery are still unknown, such as pupillary diameter, depth of the anterior chamber, Intra Ocular Pressure or astigmatism.