Comparison of fitting stability of the different soft toric contact lenses

Momeni‐Moghaddam, Hamed; Naroo, Shehzad A.; Askarizadeh, Farshad; Tahmasebi, Fatemeh

doi:10.1016/j.clae.2014.05.003

Cited by 15 publications

(18 citation statements)

References 7 publications

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“…Note that the value of C 0 2;x;y for which Sγ is maximized is the same for all graphs and can be calculated from Eq. (26). An easier alternative would be to insert a toric lens between the pupil and the planar image plane.…”

Section: B Strehl Ratio For Zc Aberrations In a Squaregaussian Pupilmentioning

confidence: 99%

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Strehl ratio and amplitude-weighted generalized orthonormal Zernike-based polynomials

Mafusire

Krüger

2017

Appl. Opt.

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The concept of orthonormal polynomials is revisited by developing a Zernike-based orthonormal set for a non-circular pupil that is transmitting an aberrated, non-uniform field. We refer to this pupil as a general pupil. The process is achieved by using the QR form of the Gram Schmidt procedure on Zernike circle polynomials and is interpreted as a process of balancing each Zernike circle polynomial by adding those of lower order in the general pupil, a procedure which was previously performed using classical aberrations. We numerically demonstrate this concept by comparing the representation of phase in a square-Gaussian pupil using the Zernike-Gauss square and Zernike-circle polynomials. As expected, using the Strehl ratio, we show that only specific lower-order aberrations can be used to balance specific aberrations, for example, tilt cannot be used to balance spherical aberration. In the process, we present a possible definition of the Maréchal criterion for the analysis of the tolerance of systems with apodized pupils.

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Section: B Strehl Ratio For Zc Aberrations In a Squaregaussian Pupilmentioning

confidence: 99%

“…This is a lens with different optical power and focal length in two orientations perpendicular to each other. This explains why toric lenses are used by ophthamologists to treat patients with astigmatism [26].…”

Section: B Strehl Ratio For Zc Aberrations In a Squaregaussian Pupilmentioning

confidence: 99%

Strehl ratio and amplitude-weighted generalized orthonormal Zernike-based polynomials

Mafusire

Krüger

2017

Appl. Opt.

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“…Firstly, there are potentially greater difficulties in the prescription of toric CLs compared with spherical CLs. For example, there may be limitations in the availability of astigmatic powers and meridians (particularly oblique) for different CL designs as stock lenses, 11 the need to deal with CL rotation, 14 , 15 (hence axis of the cylinder) and the potential for resultant differential prism between the right and left eyes in the case of prims or peripheral ballast CL designs in individuals with monocular astigmatism. 16 With respect to lens rotation and mislocation, oblique astigmatism and with-the-rule astigmatism are thought to be more challenging to correct with CLs than against-the-rule astigmatism due to CL thickness profiles and their interaction with the eyelids on the blink, which may result in poor or unstable vision.…”

Section: Introductionmentioning

confidence: 99%

Comparing spectacle and toric contact lens prescribing trends for astigmatism

Chu

Boon²,

Noh³

2018

OPTO

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BackgroundThe purpose of this study is to investigate and compare spectacle and contact lens (CL) prescription trends, with an emphasis on astigmatic refractive error prescribing differences for patients who purchase spectacles or CLs in South Korea.MethodsA retrospective study of patient records of a major optical chain in South Korea was conducted. De-identified data of age, gender, power of prescribed spectacles and/or CLs were extracted from the practice database. Inclusion criteria were being within the first 10,000 purchasers of spectacles or CLs or both.ResultsThe first 10,000 purchases comprised spectacles (59%) and CLs (41%) (male:female ratio 4:6). The proportion of purchasers who were female was significantly higher for CLs (88% female, 12% male) than spectacles (43% female, 57% male) (χ2=4480.36, df=1, P<0.0001). There was a significant difference in the proportions of purchases by age group for spectacles and CLs (χ2=3246.69, df=3, P<0.0001). Spherical power distribution of prescribed lenses was similar between the groups; however, cylinder power and axis were significantly different (P<0.0001). CL astigmatic powers were more likely to be 1.00 DC or greater, whereas the majority of spectacle lenses had astigmatic power of 0.75 DC or less. In total, 90% of toric CLs were prescribed ×180 and 9% other meridians, unlike spectacles where 50% were prescribed ×180, 14% ×90 and 40% at oblique meridians.ConclusionThere is scope for providing increased toric lens correction amongst CL wearers and increasing the proportion of wearers who are male. The estimated gap for toric lens prescription amongst CL wearers who have clinically significant astigmatism ≥0.75 DC is about 59%.

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“…Toric lenses, for the correction of the astigmatism, are characterized by a spherical value, a difference value to the most negative meridian (cylinder) and the according axis. To realize sufficient cylindrical correction using contact lenses, the angular stabilization of the lens is essential [4]. This critical angular stabilization can be affected by e.g.…”

Section: Introductionmentioning

confidence: 99%