The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Jennifer Smythe - One of the best experts on this subject based on the ideXlab platform.
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the effect of add power on distance vision with the acuvue Bifocal Contact Lens
Optometry - Journal of The American Optometric Association, 2004Co-Authors: David Ardaya, Giulia Devuono, Ivy Lin, Annie Neutgens, Peter Bergenske, Patrick Caroline, Jennifer SmytheAbstract:Purpose This study was designed to determine if subjective evaluation of quality of distance vision with the Acuvue Bifocal Contact Lens could be correlated with high- and low-contrast acuity scores. Methods LogMAR visual acuities of 20 non-presbyopic subjects were measured using high and low-contrast Bailey–Lovie charts. Each subject wore an Acuvue Bifocal Contact Lens with add powers +1.00, +1.50, +2.00, and +2.50, each optimized for best distance acuity. Results Subjects showed significantly decreased acuities with increasing add; a low-contrast target heightened this effect. Subjects reported a reduction in quality of distance vision, increasing fluctuation, ghosting/shadows, and halos around lights that correlated with increasing add power. Conclusions Our findings suggest that the Acuvue Bifocal Contact Lens may be expected to perform best for presbyopes with low-to-moderate Bifocal add requirement, and that clinicians should anticipate decreased low-contrast acuity and reduced overall quality of vision as add powers are increased.
Larry N Thibos - One of the best experts on this subject based on the ideXlab platform.
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diffractive properties of the diffrax Bifocal Contact Lens
Ophthalmic and Physiological Optics, 1993Co-Authors: David A Atchison, Larry N ThibosAbstract:We have verified that the Pilkington Diffrax® Lens behaves optically as a diffractive Bifocal Contact Lens. The longitudinal chromatic aberration of the Lens is similar to that predicted by theory, both on and off the eye. The over-refraction with the Lens on the eye is similar to the distance subjective refraction, which is also as predicted.
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Chromatic aberration and optical power of a diffractive Bifocal Contact Lens
Optometry and Vision Science, 1992Co-Authors: Ming Ye, Harun A. Rahman, Arthur Bradley, Xiaoxiao Zhang, Michael J. Collins, Larry N ThibosAbstract:Although diffractive Contact Lenses have been well documented in theory, no definitive experimental data have been reported which confirm that the near image is in fact created by diffraction rather than by refraction. We have tested the diffraction hypothesis for one type of diffractive Contact Lens (the Hydron Echelon Bifocal) experimentally by measuring its longitudinal chromatic aberration in isolation and when worn on the eye. The basis of this test is that, according to theory, diffractive Lenses should have chromatic aberration which is opposite in sign to that measured for the eye. Objective measurements of chromatic aberration were made with a focimeter when the Lens was in a wet cell. Subjective measurements were made with a Badal optometer when the Lens was worn on the eye. Four control experiments were conducted to provide baseline measurements of the eye’s chromatic aberration, against which we compared the results obtained for the diffractive Contact Lens. The data were also compared with conventional measurements of refractive error obtained by standard subjective techniques and by an automated infrared refractor. Our results showed that the longitudinal chromatic aberration of the diffraction image of the Echelon Bifocal Lens was about one-half that obtained under the four control conditions: for the naked eye, for the nondiffraction image of the Echelon Lens, or for either image of a refractive Bifocal Contact Lens (CIBA Bisoft). These results are consistent with the theoretical prediction that the negative chromatic aberration of a diffractive Contact Lens should partially cancel the positive chromatic aberration of the human eye. Conversely, it would be difficult to explain these results on the basis of any other known technique for achromatizing the human eye. We therefore conclude that diffraction is responsible for one of the images formed by the Echelon Bifocal Lens.
David Ardaya - One of the best experts on this subject based on the ideXlab platform.
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the effect of add power on distance vision with the acuvue Bifocal Contact Lens
Optometry - Journal of The American Optometric Association, 2004Co-Authors: David Ardaya, Giulia Devuono, Ivy Lin, Annie Neutgens, Peter Bergenske, Patrick Caroline, Jennifer SmytheAbstract:Purpose This study was designed to determine if subjective evaluation of quality of distance vision with the Acuvue Bifocal Contact Lens could be correlated with high- and low-contrast acuity scores. Methods LogMAR visual acuities of 20 non-presbyopic subjects were measured using high and low-contrast Bailey–Lovie charts. Each subject wore an Acuvue Bifocal Contact Lens with add powers +1.00, +1.50, +2.00, and +2.50, each optimized for best distance acuity. Results Subjects showed significantly decreased acuities with increasing add; a low-contrast target heightened this effect. Subjects reported a reduction in quality of distance vision, increasing fluctuation, ghosting/shadows, and halos around lights that correlated with increasing add power. Conclusions Our findings suggest that the Acuvue Bifocal Contact Lens may be expected to perform best for presbyopes with low-to-moderate Bifocal add requirement, and that clinicians should anticipate decreased low-contrast acuity and reduced overall quality of vision as add powers are increased.
Jaume Pujol - One of the best experts on this subject based on the ideXlab platform.
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image quality in wearers of a centre distance concentric design Bifocal Contact Lens
Ophthalmic and Physiological Optics, 2002Co-Authors: Joan Gispets, Montserrat Arjona, Jaume PujolAbstract:The optical performance of eyes wearing Bifocal concentric Contact Lens was studied using the double-pass technique. Retinal image quality was measured for four subjects wearing CIBA Bisoft Contact Lenses presenting the central zone for correcting distance vision. Lenses with two different central optic zone diameter (COZD), 3.2 and 3.8 mm, were studied and the influence of pupil diameter and viewing distance were analysed. Results show that the best optical performance is obtained for far vision conditions when no Lens is worn even if the pupil coverage by the COZD is complete. For near vision conditions, the optical performance when the Lens is worn is, in general, better than when no Lens is worn. When the Lens is worn the best optical performance corresponds to a pupil diameter of 3 mm and far vision conditions. For this pupil diameter, variations in the situations analysed can be explained by changes in the percentage of pupil coverage corresponding to the far or the near vision zone of the Lens. For a pupil diameter of 5 mm, the retinal image quality is more similar in all situations studied and pupil coverage alone cannot explain the results obtained and the influence of other parameters related to the design or Contact Lens fitting characteristics must be considered.
Ivy Lin - One of the best experts on this subject based on the ideXlab platform.
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the effect of add power on distance vision with the acuvue Bifocal Contact Lens
Optometry - Journal of The American Optometric Association, 2004Co-Authors: David Ardaya, Giulia Devuono, Ivy Lin, Annie Neutgens, Peter Bergenske, Patrick Caroline, Jennifer SmytheAbstract:Purpose This study was designed to determine if subjective evaluation of quality of distance vision with the Acuvue Bifocal Contact Lens could be correlated with high- and low-contrast acuity scores. Methods LogMAR visual acuities of 20 non-presbyopic subjects were measured using high and low-contrast Bailey–Lovie charts. Each subject wore an Acuvue Bifocal Contact Lens with add powers +1.00, +1.50, +2.00, and +2.50, each optimized for best distance acuity. Results Subjects showed significantly decreased acuities with increasing add; a low-contrast target heightened this effect. Subjects reported a reduction in quality of distance vision, increasing fluctuation, ghosting/shadows, and halos around lights that correlated with increasing add power. Conclusions Our findings suggest that the Acuvue Bifocal Contact Lens may be expected to perform best for presbyopes with low-to-moderate Bifocal add requirement, and that clinicians should anticipate decreased low-contrast acuity and reduced overall quality of vision as add powers are increased.