purpose: to evaluate agreement between galilei, orbscan ii, and placido disk-based topography in terms of keratometry readings, and anterior and posterior elevation. methods: in this prospective comparative study, 184 eyes of 92 keratorefractive surgery candidates were evaluated with galilei, orbscan ii, and placido disk-based topography. keratometry readings and anterior and posterior elevatio...

UNLABELLED ABSTRACT Purpose: To describe change in corneal astigmatism in infants and children of a Native American tribe with a high prevalence of astigmatism. METHODS Longitudinal measurements of corneal astigmatism were obtained in 960 Tohono O'odham children aged 6 months to <8 years. Change in corneal astigmatism (magnitude (clinical notation), J0, J45) across age in children with high a...

purpose: to evaluate the correlation between refractive, corneal and lenticular astigmatism and higher order aberrations (hoa) in refractive surgery candidates methods: this cross-sectional descriptive-analytical study consisted of 400 eyes (200 patients) who were referred between 2011 to 2013 to farabi eye hospital for refractive surgery. refraction, topography and aberrometry were performed t...

PURPOSE To assess the repeatability of Equivalent Keratometry Readings (EKRs) obtained by the Pentacam HR (high resolution) in untreated and post-LASIK eyes, and to compare them with the keratometry (K) values obtained by other algorithms. METHODS In this prospective study, 100 untreated eyes and 71 post-LASIK eyes were included. In the untreated group, each eye received 3 consecutive scans u...

PURPOSE To show how an incorrect manifest astigmatism axis can cause an abnormal induced astigmatism on a new axis. PATIENTS AND METHODS Four eyes of three patients were treated primarily with WaveLight® EX500 wavefront optimized (WFO) treatments for astigmatism. All four eyes needed enhancements and were analyzed retrospectively via WaveLight® Contoura to determine the reason for the incorre...

BACKGROUND To examine the influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery. METHODS The study enrolled 64 pseudophakic eyes of 50 patients (71.8 ± 9.9 years old, mean ± standard deviation) who had undergone phacoemulsification with non-toric IOL implantation. Refractive astigmatism was measured using an auto ref-ker...

PURPOSE Astigmatic subjects are adapted to their astigmatism and perceptually recalibrate upon its correction. However, the extent to which prior adaptation to astigmatism affects visual performance, whether this effect is axis dependent, and the time scale of potential changes in visual performance after astigmatism correction are not known. Moreover, the effect of possible positive interactio...

PURPOSE To investigate the distribution of posterior corneal astigmatism in eyes with with-the-rule (WTR) and against-the-rule (ATR) anterior corneal astigmatism. METHODS We retrospectively examined six hundred eight eyes of 608 healthy subjects (275 men and 333 women; mean age ± standard deviation, 55.3 ± 20.2 years). The magnitude and axis orientation of anterior and posterior corneal astig...

In irregular astigmatism, the two meridians may be located at something other than 90 degrees apart (principal meridians are not perpendicular); or there are more than two meridians. Irregular astigmatism is that in which the curvature varies in different parts of the same meridian or in which refraction in successive meridians differs irregularly. Irregular astigmatism is associated with loss ...

PURPOSE To evaluate how small amounts of astigmatism affect visual acuity and the minimum astigmatism values that should be corrected to achieve maximum visual performance. SETTING Optics Laboratory, University of Murcia, Murcia, Spain. DESIGN Case series. METHODS A wavefront sensor was used to measure astigmatism and higher-order aberrations (HOAs) in normal young eyes with astigmatism r...