BACKGROUND Albinism causes significant eye morbidity and amblyopia in children. The aim of this study was to determine the refractive state in patients with complete oculocutaneous albinism who were treated at the Gynaeco-Obstetric and Paediatric Hospital, Yaoundé, Cameroon and evaluate its effect on vision. METHODS We carried out this retrospective study at the ophthalmology unit of our hosp...

Corneal hysteresis (CH) is a parameter which measures the viscoelastic behaviour of the cornea, indicating its biomechanical integrity1. Some clinical conditions such as keratoconus, Fuchs corneal dystrophy, high myopia, glaucoma and corneal refractive surgery, may induce changes in corneal biomechanical properties, leading to a decrease in CH2-6. Astigmatism, a refractive error related to corn...

PURPOSE This study investigated the relationship between uncorrected astigmatism and early academic readiness in at-risk preschool-aged children. METHODS A vision screening and academic records review were performed on 122 three- to five-year-old children enrolled in the Philadelphia Head Start program. Vision screening results were related to two measures of early academic readiness, the tea...

Background To retrospectively analyse strategies for adjusting refractive surgery plans with reference to the preoperative manifest refraction. Methods We constructed seven nomograms based on the refractive outcomes (sphere, cylinder, axis [SCA]) of 150 consecutive eyes treated with laser in situ keratomileusis for myopic astigmatism. We limited the initial data to the SCA of the manifest ref...

BACKGROUND The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran. METHODS In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All c...

PURPOSE To determine the prevalence of refractive errors and to investigate factors associated with refractive error in adults 30 years of age and older in Bangladesh. DESIGN Cross-sectional study. PARTICIPANTS A nationally representative sample of 12 782 adults 30 years of age and older. METHODS The sample of subjects was selected based on multistage, cluster random sampling with probabi...

PURPOSE To demonstrate how using the Wavelight Contoura measured astigmatism and axis eliminates corneal astigmatism and creates uniformly shaped corneas. PATIENTS AND METHODS A retrospective analysis was conducted of the first 50 eyes to have bilateral full WaveLight® Contoura LASIK correction of measured astigmatism and axis (vs conventional manifest refraction), using the Layer Yolked Redu...

purpose : to determine the association between astigmatism and spherical refractive error in a clinical population methods : in this cross-sectional study, 2,000 patients who presented to our optometry clinic were enrolled. all were tested for objective refraction with a nidek ar-310a auto refractometer, and non-cycloplegic refraction. for those under 15 years of age, cycloplegic refraction was...

Lower order aberrations are another way to describe refractive errors: myopia, hyperopia and astigmatism, correctible with glasses, contact lenses or refractive surgery. Lower order aberrations is a term used in wavefront technology to describe second-order Zernike polynomials. Second-order Zernike terms represent the conventional aberrations defocus (myopia, hyperopia and astigmatism). Lower o...

In the optical system of the human eye, total refractive power consists mainly of corneal and lenticular components. Approximately two-thirds of the eye's converging power is at the air–cornea (tear film) interface; one-third is in the lens. Total corneal power is determined by corneal anterior and posterior curvature, corneal thickness, and the corneal refractive indices. Traditionally, anteri...