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...

In astigmatism variations in the curvature of the cornea or lens along different meridians prevent the light rays from focusing onto a single point. Corneal refraction depends on the corneal curvature. If the cornea is more curved, the power of refraction is higher and vice versa. Corneal and lenticular astigmatism can complement or cancel each other. Their summation represents the so called “t...

PURPOSE To demonstrate how higher-order corneal aberrations can cancel out, modify, or induce lower-order corneal astigmatism. PATIENTS AND METHODS Six representative eyes are presented that show different scenarios in which higher-order aberrations interacting with corneal astigmatism can affect the manifest refraction. WaveLight® Contoura ablation maps showing the higher-order aberrations a...

PURPOSE To demonstrate a case illustrating meridional lenticular astigmatism as a result of renal cell carcinoma uveal metastases. METHODS Case report with images. RESULTS Clinical findings and diagnostic testing of a patient with acquired meridional lenticular astigmatism are described. The refraction revealed best-corrected visual acuity of 20/20-1 OD (-2.50 + 0.25 × 090) and 20/50 OS (-8...

1.1 Definition Astigmatism (from the Greek “a” meaning absence and “stigma” meaning point) is a refractive error (ametropia) that occurs when parallel rays of light entering the nonaccommoding eye are not focused on the retina [American Academy of Ophthalmology (AAO), 2007]. Astigmatism occurs when incident light rays do not converge at a single focal point. The cornea of the normal eye has a u...

BACKGROUND The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. METHODS Eleven eyes with coma-like-aberrations-dominan...