Search results for "stigmat"
showing 10 items of 156 documents
Stereoacuity After Refractive Lens Exchange With AcrySof ReSTOR Intraocular Lens Implantation
2009
Purpose: To evaluate stereoacuity before and after refractive lens exchange (RLE) with AcrySof ReSTOR intraocular lens (IOL) implantation. Methods: Stereoacuity was measured using the Titmus stereotest at 40 cm under photopic conditions (85 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR Natural (SN60D3 model) implantation in 30 hyperopic eyes of presbyopes with low astigmatism (⩽1.00 diopter [D]). Stereoacuity measurements after implantation were compared with those found before surgery. Results: Stereoacuity was unchanged after RLE with pseudoaccommodative IOL implantation. In this population of non-cataractous hyperopes with excellent preoperative stereoacuity (46.42±1.36 se…
Astigmatism among myopics and its changes from childhood to adult age: a 23‐year follow‐up study
2014
Purpose To study the prevalence of and changes in astigmatism from the onset of myopia at school age. Methods Two hundred and forty myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983–1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Three annual examinations with subjective cycloplegic refraction were performed for 237–238 subjects. Subsequent examinations were performed at the mean ages of 23.2 and 33.9 years for 178 and 163 subjects, and the last examination, including data from prescriptions of different ophthalmologists, for 32 subjects. Corneal topography was studied at baseline, at the 3-year follow-up and at t…
Catalogue of the Mesostigmata mites in Finland
2016
This catalogue of Mesostigmata found in Finland is based on published records, material deposited in the Zoological Museum of Turku University, and collections by the author, deposited in the Zoological Museum of Helsinki University. The total number of recorded species is 451, including 15 unidentified or undescribed species. 121 of the identified species were not previously reported from Finland. General distribution in Finland and preferred habitats of the species are given, or of rare species the details of the records. peerReviewed
Effects of temperature and moisture fluctuations on an experimental soil microarthropod community
2001
Summary We established an experiment in microcosms with coniferous forest humus and birch leaf litter for testing the effects of constant vs. diurnally fluctuating temperature and uniform vs. varying moisture, on the population densities and species richness of Collembola and Mestostigmata. These parameters and the vertical distribution of populations were analysed by layers (top, centre, bottom) at two samplings (weeks 10 and 27). The hypotheses were that populations of at least some species benefit from fluctuating microclimate, and that varying conditions permit more species to coexist than uniform conditions. At fluctuating temperature regime, four species and total Collembola were more…
Effect of even and odd-order aberrations on the accommodation response
2017
Aim To investigate the potential effect that odd and even-order monochromatic aberrations may have on the accommodation response of the human eye. Methods Eight healthy subjects with astigmatism below 1 D, best corrected visual acuity 20/20 or better and normal findings in an ophthalmic examination were enrolled. An adaptive optics system was used in order to measure the accommodation response of the subjects' eyes under different conditions: with the natural aberrations being present, and with the odd and even-order aberrations being corrected. Three measurements of accommodation response were monocularly acquired at accommodation demands ranging from 0 to 4 D (0.5 D step). Results The acc…
Acs refrakcija un viņas noteikšana
1933
Titullapā norādīts autors: Apiņš, Kārlis
Statistical analysis when dealing with astigmatism: assessment of different spherocylindrical notations.
2001
Ophthalmic epidemiological studies frequently deal with ocular refractive errors, which are commonly expressed in the form sphere/cylinder x axis. However, this representation has been shown not to be the most suitable one for performing statistical analysis. Although alternative analytical and graphic methods to represent this kind of data have been developed, these formalisms have often gone unnoticed by researchers, despite their usefulness and versatility. Besides, there has been no discussion of how each of them fits in with a particular type of study. In this paper, several mathematical representations of dioptric power are revisited in a comprehensive way. The aim is to encourage res…
Optical Quality Comparison of Conventional and Hole-Visian Implantable Collamer Lens at Different Degrees of Decentering
2012
To compare the optical quality of implantable Collamer lens (ICL) with and without central hole (Hole ICL and conventional ICL) at different degrees of decentering.Experimental laboratory investigation.Wavefront aberrations of the -3, -6, and -12 diopter (D) V4b and -3, -6, and -12 D V4c ICLs were measured in 3 conditions-centered and decentered 0.3 and 0.6 mm-at 3-mm and 4.5-mm pupils. The root mean square of total higher order aberrations, trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, point spread function and simulated retinal images of ICLs were calculated from the wavefront aberrations for each ICL and all conditions of decenteri…
Predictability of intraocular lens power calculation after small-incision lenticule extraction for myopia
2019
PURPOSE To evaluate and compare the predictability of intraocular lens (IOL) power calculation after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism. SETTING Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany. DESIGN Retrospective comparative case series. METHODS Preoperative evaluation included optical biometry using IOLMaster 500 and corneal tomography using Pentacam HR. The corneal tomography measurements were repeated at 3 months postoperatively. The change of spherical equivalent due to SMILE was calculated by the manifest refraction at corneal plane (SMILE-Dif). A theoretical model, involving the virtual implantation of the same…
Residual astigmatism produced by toric intraocular lens rotation.
2010
Purpose To analyze changes in the eye’s refractive properties when a toric intraocular lens (IOL) rotates. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Design Experimental study. Methods The matrix definition of astigmatism was used in this theoretical study and compared with another vector representation. Two methods were compared: (1) The cylinder, C, resulting from the addition of 2 cylinders C1 and C2 whose axes form an angle a, is obtained by the addition of 2 vectors of values C1 and C2 forming an angle 2a; (2) the power matrix, F, of a thin astigmatic dioptric system that decomposes naturally into 3 orthogonal components: the purely spherical part Fnes, the orth…