Search results for "refractive error"
showing 5 items of 125 documents
Optical quality of the diabetic eye: a review
2014
Diabetes mellitus is a metabolic disorder characterized by the presence of chronic hyperglycaemia. Several structural, morphological, and physiological changes in each of ocular component have been described in detail during the past decades. Due to these abnormalities, the diabetic patient undergoes a degradation of the retinal image by an increase of higher ocular aberrations and ocular scattering coming from mainly tear film, cornea, and crystalline lens. This review aims to provide an overview of current knowledge about the effects of diabetes mellitus in these optical phenomena and its consequence on the visual quality of the diabetic patient.
Role of the tear film in the optical quality of the human eye.
2007
This paper reviews recent studies of the role of the tear film in the optical quality of the eye. Recent investigations focus on the dynamics of the tear film after a blink and its important role in the optical quality of the eye. The results in this review were used in an attempt to understand the optical and visual impact of tear-film breakup in normal eyes and dry eyes. It was noted that patients with dry-eye syndrome have large optical aberrations compared with those in normal eyes, which may be the cause of blurry vision associated with the syndrome. In addition, instillation of artificial tears reduces optical aberrations and thus improves the optical quality of vision in these patien…
Optical quality of hyperopic and myopic phakic intraocular lenses
2013
Aims: To assess and compare the optical quality of the myopic and hyperopic implantable collamer lens (ICL) from its wavefront aberrations for different powers and pupil diameters. Settings and Design: Prospective study. Material and Methods: The wavefront aberrations of two myopic (−3 and −6 diopters (D)) and two hyperopic V4b ICLs (+3 and +6D) were measured in vitro . To assess and compare the optical quality of different powers of ICLs, we analyzed the root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration at 3- and 4.5-mm pupil. In addition, the point spread functions (PSFs) of each ICL evaluated were ca…
Associations of Children’s Close Reading Distance and Time Spent Indoors with Myopia, Based on Parental Questionnaire
2022
Purpose: To study the association of parents’ reports about their children’s near work and outdoor habits with myopia in their children. Methods: Data from a questionnaire study conducted in 1983 among Finnish schoolchildren were reanalyzed. Vision screening had been performed for all the schoolchildren (n = 4961) in the 1st, 5th, and 8th grades (7-, 11-, and 15-year-olds) in an area of Central Finland. The questionnaire, including information about myopia, was returned by 4305 (86.7%) participants. Items concerned parents’ estimates of their child’s habitual reading distance, time spent indoors as compared with age peers, daily near work, outdoors time, and parents&…
Virskorekcijas pielietojamība tuvredzības progresijas novērtēšanā ortokeratoloģijas pacientiem
2022
Darbs ir uzrakstīts angļu valodā uz 93 lapaspusēm. Tas satur 49 attēlus, 24 tabulas un 95 atsauces uz literatūras avotiem. Šī darba mērķis ir pārbaudīt, vai virskorekcija ir derīga metode tuvredzības progresēšanas novērtēšanai ortokeratoloģijā. Hipotēze ir atrast lielākas izmaiņas gados jaunākiem pacientiem nekā pieaugušajiem, kā tas ir norādīts literatūrā. Pētījumā iekļauti 192 Eiropeīdās rases subjekti vecumā no 6 līdz 56 gadiem (vidēji 19,61±10,30). Izmantojot retrospektīvu analīzi, no objektīva BOZR kontaktlēcas parametra tiek iegūta virskorekcija (ORX). Jaunākiem cilvēkiem ir lielākas ORX vērtības, bet pieaugušajiem nav atšķirības (p<0,05). Vidēji tuvredzība progresēja par –0,18±0,44 D…