Results 201 to 210 of about 109,795 (255)

Calculation of the thickness of an intraocular lens

Journal of Cataract and Refractive Surgery, 1993
Lens manufacturers do not usually supply information about the central thickness of an intraocular lens optic. This paper describes a method to calculate the central lens thickness from variables normally supplied by the manufacturer, i.e., the total lens power in situ, the edge thickness, the optic diameter, and some knowledge of the optic ...
K, Naeser, E V, Naeser
openaire   +2 more sources

The Impact of Hydrogel Lens Settling on the Thickness of the Tears and Contact Lens

Investigative Ophthalmology and Visual Science, 2004
To investigate the effect of contact lens insertion on the thickness on the prelens tear film (PLTF), the contact lens, and the postlens tear film (PoLTF).Twelve contact lens wearers (mean age, 32.7 years; four males) inserted etafilcon A hydrogel lenses (power: -2.00 D, base curve: 8.3 mm) in both eyes immediately before testing.
Jason J. Nichols, P Ewen King-Smith
exaly   +3 more sources

The Definition of Thickness for a Lens

American journal of optometry and physiological optic, 1979
Abstract The thickness of a lens depends upon the direction of the measuring vector. The thickness as commonly used from the sagittal height formula does not give the path length for movement of gas, water, or heat through a lens.
openaire   +2 more sources

Characteristics of the thick, compound refractive lens

Applied Optics, 2003
A compound refractive lens (CRL), consisting of a series of N closely spaced lens elements each of which contributes a small fraction of the total focusing, can be used to focus x rays or neutrons. The thickness of a CRL can be comparable to its focal length, whereupon a thick-lens analysis must be performed.
Richard H, Pantell, Joseph, Feinstein, H Raul, Beguiristain, Melvin A, Piestrup, Charles K, Gary, Jay T, Cremer   +5 more
openaire   +2 more sources

THE GEL LENS—TRANSFERRED CORNEAL TORICITY AS A FUNCTION OF LENS THICKNESS

Optometry and Vision Science, 1972
ABSTRACT This study was designed to determine the corneal toricity which is transferred to the front surface of a gel contact lens as the thickness of the lens varies. Five different Griffin Hydrogel contact lenses of essentially the same dimensions, except thickness. were used.
A N, Lee, D S, Sarver
openaire   +2 more sources

Determination of the Average Thickness of a Contact Lens

Optometry and Vision Science, 1981
Abstract The amount of gas moving through a contact lens depends upon its permeability to the gas and its thickness. The lens thickness used to calculate transmissibility is often the center thickness, which is rarely the average lens thickness.
openaire   +2 more sources

Understanding lens thickness

Optician, 2016
Andy Sanders takes a look at lens thickness and what should be borne in mind to offer our patients the best appearance and wearing comfort when dispensing any particular refractive correction.
openaire   +1 more source

Application of Hydrogel Lens Average Thickness

Optometry and Vision Science, 1984
ABSTRACT The equation for the average thickness of a hydrogel lens is a complex function. This report gives a simple method of estimating this parameter. By structuring the information into nomograms, an accurate system is derived which facilitates the design of a contact lens to provide a required average oxygen transmissibility ...
openaire   +2 more sources

Aberration design of zoom lens systems using thick lens modules

Applied Optics, 2014
A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval ...
Jinkai, Zhang, Xiaobo, Chen, Juntong, Xi, Zhuoqi, Wu   +3 more
openaire   +2 more sources

Relationship of the actual thick intraocular lens optic to the thin lens equivalent

American Journal of Ophthalmology, 1998
To theoretically derive and empirically validate the relationship between the actual thick intraocular lens and the thin lens equivalent.Included in the study were 12 consecutive adult patients ranging in age from 54 to 84 years (mean +/- SD, 73.5 +/- 9.4 years) with best-corrected visual acuity better than 20/40 in each eye. Each patient had bilateral
J T, Holladay, K J, Maverick
openaire   +2 more sources