Search results for "Corneal topography"
showing 10 items of 61 documents
The utility of measuring tear film break-up time for prescribing contact lenses.
2017
Abstract Purpose To evaluate the clinical value of non-invasive keratograph tear film breakup time (NIKBUT) in the assessment of pre-corneal and pre-lens tear film quality for prescribing contact lenses (CLs). Methods Forty-six subjects aged 25.5 ± 4.3 (mean ± standard deviation) years were recruited. Visual acuity (VA), anterior eye health checks and NIKBUT were evaluated. On the following day, subjects were fitted with a daily Silicon Hydrogel (SiHy) CL in one eye and a Hydrogel (Hy) CL in the other. After four hours one material for both eyes was chosen based on a qualitative analysis which included VA, CL fitting and comfort. Information about the first and the mean NIKBUT was then cont…
What is the influence of parents' myopia on their children's myopic progression? A 22-year follow-up study.
2016
Purpose To study the connection between parental myopia and their children's myopia from school age to adulthood. Methods Two hundred and forty myopic schoolchildren (119 boys, 121 girls, mean age 10.9 years) with no previous spectacles for myopia were recruited to a 3-year treatment trial with different use of spectacles. Follow-ups were performed at mean ages of 13.9, 23.7 and 33.2 years for 238, 176 and 170 subjects respectively. Subjective refraction was calibrated to the spherical equivalent at corneal level (SEcor). Corneal refractive power (CR) and axial length (AL) were measured. Parental myopia was assessed with a questionnaire and the children assigned accordingly to one of three …
Genome-wide association meta-analysis of corneal curvature identifies novel loci and shared genetic influences across axial length and refractive err…
2020
Corneal curvature, a highly heritable trait, is a key clinical endophenotype for myopia - a major cause of visual impairment and blindness in the world. Here we present a trans-ethnic meta-analysis of corneal curvature GWAS in 44,042 individuals of Caucasian and Asian with replication in 88,218 UK Biobank data. We identified 47 loci (of which 26 are novel), with population-specific signals as well as shared signals across ethnicities. Some identified variants showed precise scaling in corneal curvature and eye elongation (i.e. axial length) to maintain eyes in emmetropia (i.e. HDAC11/FBLN2 rs2630445, RBP3 rs11204213); others exhibited association with myopia with little pleiotropic effects …
Lentes de contato corneoesclerais adaptadas em córneas irregulares após cirurgia LASIK
2018
ABSTRACT Purpose: We aimed to describe the outcomes of corneoscleral contact lens fitting with multi-aspherical geometry designs in patients with irregular corneas after laser-assisted in situ keratomileusis (LASIK). Methods: This was a retrospective series of 18 patients (age, 26-38 years) selected from an eye clinic database. Participants were required to have unsatisfactory visual acuity with their current contact lenses or spectacles after LASIK for myopia correction. All patients were fitted with corneoscleral contact lenses designed to correct corneal surface irregularities. A diagnostic trial set was used for fitting, and assessments were performed according to a standardized methodo…
Corrigendum to “Short-term changes in light distortion in orthokeratology subjects"
2015
Artigo completo publicado na revista "BioMed Research International, (2015), 1-7" e disponível no RepositóriUM em: http://hdl.handle.net/1822/33375
The relationship between central corneal thickness and Goldmann applanation tonometry
2003
The aim of this study was to investigate the relationship between Goldmann applanation tonometry and central corneal thickness in a large sample of healthy eyes.Five hundred eyes of 500 subjects (253 women, 50.6 per cent and 247 men, 49.4 per cent) were analysed in a prospective healthy population study. Mean age of the sample was 31 +/- 8 years. Goldmann applanation tonometry was carried out by one physician. Tonometric values were the mean of three consecutive readings. Subsequently, another physician carried out ultrasonic pachymetry with the DGH 2000 AP ultrasonic pachymeter (DGH Technology Inc, San Diego, USA). Ten measurements were made at the centre of the cornea of each eye. The low…
Reproducibility of optical biometry using partial coherence interferometry: intraobserver and interobserver reliability
2001
Abstract Purpose: To evaluate the intraobserver and interobserver variability in axial length (AL), anterior chamber depth (ACD), and corneal radius measurements using an optical biometry instrument based on partial coherence interferometry (PCI). Setting: Johannes Gutenberg University, Mainz, Germany. Methods: In this observational case series and interobserver reliability trial, 30 healthy, emmetropic to moderately myopic eyes of 15 volunteers were evaluated. The AL, ACD, and corneal radius were measured 20 times in 10 eyes by 1 observer to evaluate the intraobserver variability. To evaluate the interobserver variability, the measurements were taken in 20 eyes by 5 different observers. Me…
Interchangeability among five devices that measure anterior eye distances.
2014
The aim was to study the interchangeability of various devices that measure anterior chamber depth (ACD) and white-to-white (WTW) distance.Eighty right eyes of eighty patients aged 20 to 40 years were included. Their spherical equivalent ranged from -4.25 to +1.00 dioptres. Each eye's ACD and the WTW distance were measured using the following devices: a Castroviejo surgical calliper, CA-200F Corneal Analyser, Orbscan II, Pentacam HR and IOLMaster 500.The Pentacam HR measured significantly greater ACD (p0.01) than the other two devices, whereas IOLMaster 500 and Orbscan II yielded comparable (p0.01) distances. Nonetheless, in every device comparison, the mean difference was within clinically…
Repeatability of whole-cornea measurements using an anterior segment imaging device based on OCT and Placido-disk
2017
Current advances in refractive surgery require high accuracy of corneal measurements. We aim to evaluate the repeatability of topographic measurements using an integrated Placido disk - OCT device.Thirty right eyes of thirty healthy and young subjects were included. The topographic parameters of simulated keratometry, asphericity, minimum pachymetry, white-to-white distance, spherical aberration and corneal elevation were studied. Three measurements were taken by the same observer using the Visante omni device. The coefficient of repeatability (CoR), coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated to assess the repeatability. The Bland-Altman grap…
Assessment of modifications in thickness, curvatures, and volume upon the cornea caused by disposable soft contact lens wear.
2015
Purpose To assess the effect of different disposable soft contact lenses on several corneal parameters–-thickness, anterior and posterior curvature, and volume–-by means of a Scheimpflug imaging-based device (Pentacam HR). Diurnal variations of these parameters were taken into account. Methods Twenty-one young, healthy subjects wore 4 different types of daily disposable soft contact lenses on 4 different days: Dailies AquaComfort Plus, SofLens, Dailies Total1, and Acuvue TruEye. The lenses had different material and water content. Pachymetry and curvature maps and corneal volume values were obtained using the Pentacam HR twice a day: one before putting the lens on and one after an 8-hour pe…