PURPOSE To determine the safety and efficacy of wavefront-guided LASIK for the correction of low to moderate myopia, as performed by surgeons employed by Optical Express, a large corporate provider. METHODS Data were extracted from the Optical Express central database on 22,900 patients (42,143 eyes) who underwent primary LASIK to treat low to moderate myopia and/or astigmatism. All treatment...

The corneal topographer is an indispensable tool and plays a critical role in the practice of refractive surgery. In corneal refractive surgery, corneal topography is used preoperatively to detect irregular astigmatism, ectatic corneal disorders, or other abnormalities, and to monitor topographic stability following discontinuation of contact lens wear. Postoperatively, it is used to monitor an...

PURPOSE To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. METHODS The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were als...

Laser vision correction is a rapidly growing field for correcting nearsightedness, farsightedness as well as astigmatism with dominating laser-assisted in situ keratomileusis (LASIK) procedures. While the technique works well for correcting spherocylindrical aberrations, it does not fully correct high order aberrations (HOAs), in particular spherical aberration (SA), due to unexpected induction...

PURPOSE To observe torsional movements of the eye in refractive surgery, and their possible consequences in the surgery outcome. METHODS In a prospective study, 49 eyes of 40 patients were submitted to surgical correction of astigmatism, by the LASIK technique. Patients were divided in two groups based on the cylindric power. Group A from -0.25 to -2.00D; group B from -2.25 to -6.00D. The occ...

PURPOSE The authors describe a technique of laser in situ keratomileusis (LASIK) for the management of postkeratoplasty ametropia using a femtosecond laser for flap creation. METHODS The first step was the placement of a disposable suction fixation ring to ensure that it was well-centered on the graft. The applanation cone was applied; the border of the flap was adjusted according to the edge...

Keratoconus (KCN) is an ectatic disorder with progressive corneal thinning and a clinical picture of corneal protrusion, progressive irregular astigmatism, corneal fibrosis and visual deterioration. Other ectatic corneal disorders include: post-LASIK ectasia (PLE) and pellucid marginal degeneration (PMD). Corneal crosslinking (CXL) is a procedure whereby riboflavin sensitization with ultraviole...

Optical aberrations lead to defects in image-forming, the image obtained being imperfect and thereby decreasing the quality of vision. When an optic system is not perfect, as happens with the eye, the rays of light that pass through the system produce optical aberrations. The purpose of this review is to describe optical aberrations and their impact on vision and how refractive surgery outcomes...

OBJECTIVE To assess the preoperative central corneal thickness (CCT) of myopic and/or astigmatism patients presenting for refractive surgery in a tertiary hospital in Yemen. METHODS In this hospital-based cross-sectional study, 2,304 subjects aged 18-50 years with myopia and myopic astigmatism who presented to the refractive surgery unit were recruited. Data for the current study was collecte...