Search results for "emmetrop"
showing 10 items of 39 documents
The Effect of Anesthetic Eye Drop Instillation on the Distribution of Corneal Thickness
2012
PURPOSE To address the effect of topical instillation of oxybuprocaine on the relative distribution of corneal thickness (CT) in young healthy subjects. METHODS Prospective study involving 30 eyes of 30 emmetropic subjects (24 ± 3 years). Corneal thickness measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 4% using slit-scanning corneal topography (Orbscan topography system II). No acoustic correction factor was applied. The mean of 5 consecutive Orbscan measurements was obtained at the center and 3 mm from the visual axis in the temporal, superior, nasal, and inferior hemimeridians. RESULTS No significant mean differences were found at any corneal lo…
Clear Lens Extraction with Multifocal Apodized Diffractive Intraocular Lens Implantation
2007
Purpose To assess efficacy, safety, predictability, and stability after clear lens extraction (CLE) with multifocal diffractive intraocular lens (IOL) implantation. Design Prospective, nonrandomized, masked observational case series (self-controlled). Participants Two hundred twenty-four eyes of 112 consecutive patients after CLE with bilateral AcrySof ReSTOR Natural IOL implantation. Eyes were divided into myopic (mean spherical equivalent [SE], −6.01±2.71 diopters [D]) and hyperopic (mean SE, +3.86±2.52 D) groups. Methods Monocular and binocular uncorrected distance visual acuity (VA), best-corrected distance VA, uncorrected distance near VA, and best distance-corrected near VA were recor…
Relationship among Corneal Biomechanics, Refractive Error, and Axial Length
2014
Purpose To evaluate the relationship between different ocular and corneal biomechanical parameters in emmetropic and ametropic healthy white children. Methods This study included 293 eyes of 293 healthy Spanish children (135 boys and 158 girls), ranging in age from 6 to 17 years. Subjects were divided according to the refractive error: control (emmetropia, 99 children), myopia (100 children), and hyperopia (94 children) groups. In all cases, corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer system. Axial length (AL) and mean corneal power were also measured by partial coherence interferometry (IOLMaster), and central corneal thickne…
Effect of sport-tinted contact lenses for contrast enhancement on retinal straylight measurements
2008
PURPOSE: To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method. METHODS: Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred. RESULTS: The subjects' mean straylight values were 0.90 +/- 0.09 at baseline and 0.95 +/- …
Ocular Refraction at Birth and Its Development During the First Year of Life in a Large Cohort of Babies in a Single Center in Northern Italy
2020
The purpose of this study was to investigate refraction at birth and during the first year of life in a large cohort of babies born in a single center in Northern Italy. We also aimed to analyze refractive errors in relation to the gestational age at birth. An observational ophthalmological assessment was performed within 24 h of birth on 12,427 newborns. Refraction was examined using streak retinoscopy after the administration of tropicamide (1%). Values in the range of between +0.50 ≤ D ≤ +4.00 were defined as physiological refraction at birth. Newborns with refraction values outside of the physiological range were followed up during the first year of life. Comparative analyses were condu…
Clinical use of the ocular point spread function for retinal image quality assessment
2008
The purpose of this study is to demonstrate the clinical use of the point spread function (PSF) as metric for the assessment of retinal image quality in eyes with different ocular conditions. The PSF was computed from the wavefront aberrations obtained in seven eyes with different ocular conditions: emmetropia, myopia, hyperopia, post-myopic laser in situ keratomileusis (LASIK), post-hyperopic LASIK, keratoconus, Intacs ® in keratoconus, radial keratotomy (RK), LASIK after RK, cataract, phacoemulsification after cataract surgery, and LASIK after astigmatic keratotomy. The Strehl intensity ratio was calculated for all the PSFs computed. The PSF was correlated with the change in the optical e…
Genetic variants linked to myopic macular degeneration in persons with high myopia: CREAM Consortium.
2019
Purpose: To evaluate the roles of known myopia-associated genetic variants for development of myopic macular degeneration (MMD) in individuals with high myopia (HM), using case-control studies from the Consortium of Refractive Error and Myopia (CREAM). Methods: A candidate gene approach tested 50 myopia-associated loci for association with HM and MMD, using meta-analyses of case-control studies comprising subjects of European and Asian ancestry aged 30 to 80 years from 10 studies. Fifty loci with the strongest associations with myopia were chosen from a previous published GWAS study. Highly myopic (spherical equivalent [SE] ≤ -5.0 diopters [D]) cases with MMD (N = 348), and two sets of cont…
Pràctica 1. Presbícia. Laboratori d'Òptica Fisiològica
2023
El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València. Aquest és un guió de la pràctica 1 de l'assignatura d'Òptica Fisiògica, on s'aborda com estudiar i comprovar al laboratori què els passa als pacients prèsbites, i com cal compensar-los òpticament per a que funcionen bé, treballant amb un model d'ull simplificat i un altre de reduït. This is a script for practice 1 of Physiological Optics subject. In it, we addressed how to study and check in the laboratory what happens with presbyopic patients, and how to compensate them optically so that they work well. To do it, we will work with a simplified eye mod…
Neural Adaptation to Optical Quality Defects
2010
From an optical perspective the eye is far from perfect. This is a fact that is extensively supported by literature; for instance, Prof. Navarro recently provided us with a fantastic critical review on the various theories behind the different eye models and their flaws.1 The human eye has considerable amounts of higher-order aberrations even when it is emmetropic,2 with great inter-individual variability. Besides, higher-order aberrations are still postulated to have a role in the development of the refractive error, although it is not clear the extent to which this may be (see Charman WN for a review).3 The known optical limitations of the normal human eye raised the question as to what t…
Pràctica 1: Emmetropia i presbícia
2021
El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València. Guió de la primera pràctica de l'assignatura d'Òptica Fisiològica del Grau d'Òptica i Oprtometria de la Universitat de València Script of the first practice of Physiological Optics subject of the Optics and Optometry Degree of the University of Valencia