Results 21 to 30 of about 78,366 (184)

Corneal asphericity and its related factors [PDF]

Medical Hypothesis, 2023
Background: Proper correction of spherical aberration using intraocular lenses requires precise selection of the sphericity of intraocular lens surfaces based on individual biometric data and corneal asphericity coefficient (Q value). This study aimed to determine and analyze the corneal Q value and its related factors among Saudi participants. ...
Al-Somali A, Abouollo H, Al-Jindan M, Alothman A, Alhataln H.   +4 more
europepmc   +6 more sources

Anterior corneal profile with variable asphericity [PDF]

Applied Optics, 2009
We present a corneal profile in which the eccentricity, e(Q=-e(2)), has a nonlinear continuous variation from the center outwards. This nonlinear variation is intended to fit and reproduce our current experimental data in which the anterior corneal surface of the human eye exhibits different values of e at different diameters. According to our clinical
Marco A, Rosales, Montserrat, Juárez-Aubry, Estela, López-Olazagasti, Jorge, Ibarra, Eduardo, Tepichín   +4 more
core   +5 more sources

Corneal power modelling with OCT data - Thin and thick lens paraxial models versus raytracing. [PDF]

Acta Ophthalmol
Abstract Background Evaluating keratometric power with Zeiss index (PKZ), paraxial thick cornea power (Gullstrand [PG]) and power referenced to the front (PFV) and back vertex plane (PBV) and raytracing power (PR), and modelling the deviation from PKZ with a multivariable linear prediction model.
Langenbucher A, Szentmáry N, Cayless A, Hoffmann P, Wendelstein J.   +4 more
europepmc   +2 more sources

Ray-Tracing-Based Intraocular Lens Power Calculation in Combined Cataract Surgery and Descemet Membrane Endothelial Keratoplasty. [PDF]

Clin Exp Ophthalmol
ABSTRACT Background To compare the predictive accuracy of ray tracing‐based intraocular lens (IOL) power calculation formulas with the Barrett Universal II (BUII) formula in eyes with Fuchs endothelial corneal dystrophy (FECD) undergoing combined cataract surgery and Descemet membrane endothelial keratoplasty (triple DMEK).
Weber JO, Kaiser KP, Wendelstein JA, Dick HB, Kohnen T, Schmack I.   +5 more
europepmc   +2 more sources

Corneal tomographic and densitometric characteristics in children with allergic conjunctivitis: a comparative pentacam AXL study [PDF]

BMC Ophthalmology
Purpose To explore corneal tomographic and densitometric parameters associated with subtle corneal alterations in children with allergic conjunctivitis using the Pentacam AXL system. Methods This cross-sectional study included 64 eyes of 32 children with
Arzu Karakiraz, Semih Çakmak, Bekir Karakaya, Emre Altınkurt, Kamran Beyza Yalçın, Ecem Üstündaş Uzun, Zeynep Ülker Altınel   +6 more
doaj   +2 more sources

Age-Related Variations in Corneal Asphericity and Long-Term Changes

Eye & Contact Lens: Science & Clinical Practice, 2019
Purpose: Corneal front-surface asphericity is directly related with the optical quality of the eye and with contact lenses fitting. The purpose of this study was to evaluate the corneal asphericity as a function of age, sex, and refractive error measured with autokeratometry and corneal topography and its long-term changes (5 ...
Amorim-de-Sousa, Ana, Vieira, Ana Cláudia, González-Méijome, José Manuel, Queirós, A.   +3 more
openaire   +4 more sources

Age-related changes in corneal parameters in the Turkish population: a Pentacam-based study [PDF]

BMC Ophthalmology
Purpose To evaluate anterior and posterior corneal surfaces and anterior segment parameters in the Turkish population using Pentacam, and to analyze age-related changes.
Denizcan Özizmirliler, İsmet Durak
doaj   +2 more sources

Multi-aspheric description of the myopic cornea after different refractive treatments and its correlation with corneal higher order aberrations [PDF]

Journal of Optometry, 2012
Background: To analyse the asphericity of the anterior corneal surface (ACS) for different diameters, and correlate those values with corneal higher order aberrations (cHOA) before and after myopic treatments with corneal refractive therapy (CRT) for ...
António Queirós, César Villa-Collar, Jorge Jorge, Ángel Ramón Gutiérrez, José Manuel González-Méijome   +4 more
doaj   +2 more sources

Effects of corneal epithelial remodeling on corneal asphericity after FS-LASIK and Trans-PRK: A prospective study [PDF]

Indian Journal of Ophthalmology
Purpose: To observe the changes in corneal epithelial thickness after FS-LASIK and Trans-PRK surgery and to investigate the impact of corneal epithelial remodeling on Q-value and HOA.
Mingyu Xu, Fan Yang, Emmanuel Eric Pazo, Qiwei Li, Zheng Yang, Yue Huang, Shaozhen Zhao   +6 more
doaj   +2 more sources

Corneal asphericity and spherical aberration after refractive surgery

Journal of Cataract and Refractive Surgery, 2011
To evaluate changes in corneal asphericity (Q) and spherical aberrations after refractive surgery using Scheimpflug imaging.University of California, San Diego, Shiley Eye Center, La Jolla, California, USA.Cohort study.After wavefront-guided laser in situ keratomileusis, patients within ± 0.50 diopter of plano and with an uncorrected distance visual ...
Bottos, Katia M. UNIFESP, Leite, Mauro T. UNIFESP, Aventura-Isidro, Marichelle, Bernabe-Ko, Jennifer, Wongpitoonpiya, Noppamas, Ong-Camara, Nikki Heidi, Purcell, Tracy L., Schanz, David J.   +7 more
openaire   +4 more sources