Results 151 to 160 of about 78,366 (184)

Aspheric Intraocular Lens Selection Based on Corneal Wavefront

Journal of Refractive Surgery, 2009
Purpose: To determine the feasibility of selectively targeting zero total postoperative spherical aberration by selecting the best fit aspheric intraocular lens (IOL) based on preoperative topographically derived corneal spherical aberration. Methods: Candidates for cataract surgery
Mark, Packer, I Howard, Fine, Richard S, Hoffman   +2 more
openaire   +2 more sources

[Corneal asphericity in myopes].

Journal francais d'ophtalmologie, 2002
To study the variations of corneal asphericity in a population of myopic patients.One hundred consecutive myopic patients were included in this study. The EyeSys videokeratoscope was used to assess the corneal topography of these patients seeking refractive surgery.
M, Haouat, D, Gatinel, M H, Duong, H, Faraj, O, Prisant, F, Reyal, T, Hoang-Xuan   +6 more
openaire   +1 more source

Corneal Asphericity and Visual Function After Radial Keratotomy

Cornea, 1993
Corneal asphericity was measured before and after surgery in 81 radial keratotomy eyes. Asphericity was calculated between keratoscope rings 2 and 9, representing corneal diameters of 2.3 mm and 7.6 mm. Statistical methods were used to assess the relationship between postoperative asphericity and undilated, uncorrected visual acuity.
openaire   +2 more sources

[A review of mathematical descriptors of corneal asphericity].

Journal francais d'ophtalmologie, 2002
Corneal asphericity may be modeled on a conic section which can be described by the apical radius of curvature in the meridian studied and by a measure of the degree of asphericity.Through an extensive review of the literature, we expose the principles, the population variations and report the application of such corneal modeling.The aspheric anterior ...
D, Gatinel, M, Haouat, T, Hoang-Xuan
openaire   +1 more source

Characterization of the aspheric corneal surface with intrastromal corneal ring segments.

Journal of refractive surgery (Thorofare, N.J. : 1995), 1999
Anterior corneal surface asphericity was examined in eyes of Phase II clinical trial participants, before and after intrastromal corneal ring segments (ICRS, Intacs) refractive surgery, and surveyed for relationship to clinical visual performance.Aspheric test objects with surface asphericity (Q) ranging from -0.01 Q to -1.44 Q and base radius of ...
D K, Holmes-Higgin, P C, Baker, T E, Burris, T A, Silvestrini   +3 more
openaire   +1 more source

Corneal Asphericity and Its Related Factors in 1052 Chinese Subjects

Optometry and Vision Science, 2011
ABSTRACT Purpose. To observe and analyze corneal asphericity and its related factors in Chinese subjects. Methods. The corneal asphericity of 1052 right eyes from a Chinese population was determined using the ...
Zhengwei, Zhang, Jiayin, Wang, Weiran, Niu, Mingming, Ma, Kelimu, Jiang, Ping, Zhu, Bilian, Ke   +6 more
openaire   +2 more sources

Corneal Asphericity and Its Implications for Photorefractive Keratectomy: a Mathematical Model

Journal of Refractive Surgery, 1996
ABSTRACT BACKGROUND: Several clinical trials investigating myopic excimer laser photorefractive keratectomy (PRK) report an initial change in refraction from myopia to hyperopia, followed by a gradual regression toward emmetropia and occasionally to recurrent myopia.
S, Patel, J, Marshall
openaire   +2 more sources

Corneal Asphericity and Visual Function After Wavefront‐Guided LASIK

Optometry and Vision Science, 2006
ABSTRACT Purpose. In recent years, a theory has been advanced that corneal asphericity in and of itself determines visual function; that the natural, optimal shape of the cornea is prolate; and that changing the cornea from prolate to oblate negatively impacts visual results.
Kuang-mon Ashley, Tuan, Dimitri, Chernyak   +1 more
openaire   +2 more sources

Precision of Orbscan II Assessment of Anterior Corneal Curvature and Asphericity

Journal of Refractive Surgery, 2009
Purpose: To determine the number of measurements required to produce a representative mean result for corneal apical radius and asphericity and to examine the repeatability of this mean result. Methods: The Bausch & Lomb Orbscan II corneal topographer was used to ...
William Arthur, Douthwaite, Annette, Parkinson   +1 more
openaire   +2 more sources

Reducing edge lift of an aspheric corneal lens

International Contact Lens Clinic, 1990
It is because a cornea1 lens with an aspheric ocular surface is a continuous curve that becomes progressively flatter from the apex toward the periphery that the edge lift of the lens can increase as the overall lens size is made larger. Making the overall lens size smaller will reduce the amount of edge lift and make the lens fit more secure.
openaire   +1 more source