Wavefront analysis of wearing rigid gas permeable contact lenses with different designs
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Objective To compare aberrations in eyes wearing different designs of rigid gas permeable contact lenses (RGPCLs) using a wavefront analyzer.Methods Forty-eight eyes of 24 patients were included in this two-phase crossover design study.They were randomly divided into two groups with 24 eyes of 12 patients in each group.One group wore Meikang lenses (spherical design) first and then wore Menicon Z lenses (aspherical design) one month later.The order was reversed for the other group.An Allegretto wavefront analyzer was used for analyzing aberrations.data were analyzed with crossover design ANOVA.Results There were no significant differences for the root mean square (RMS) values with different lens designs:RMSMenicon [(0.439±0.183)μm] vs RMSMeikang [(0.427±0.190)μm].However,there were some differences for single aberrations:Z20 (F=56.175,P＜0.01) was larger with Menicon lenses than with Meikang lenses.On the contrary,Z22 (F=4.263,P=0.029) and Z44 (F=3.410,P=0.037) were larger with Meikang than with Menicon.Conclusion Different designs for RGPCLs had no significant effect on the RMS values.However, the negative tear-lens caused by aspheric lenses may lead to more positive defocus.At the same time, the aspheric lens design can control astigmatism and some higher-order aberrations better than the spherical lens.
Key words:
Aberration; Contact lenses,rigid gas permeable; Contact lenses,aspheric; CorneaKeywords:
Astigmatism
Root mean square
Purpose Contact lenses (CLs) used for myopia control incorporate variable power distribution across the optic zone potentially creating degradation of the high-order aberrations. The present study aims to evaluate the retinal image quality and visual performance in three prototypes of CLs intended to control axial elongation of the eye before they are considered for clinical trials.Methods This is a non-dispensing cross-over, double-blind study where 30 right eyes of myopic subjects worn 3 multifocal test lenses and 1 monofocal control lens in random order. Lens 1 was a radial refractive gradient design (center distance) and Lens 2 and 3 center-near with an additional annular ring for near. Nominal add power was 2.00D, 1.50D, and 2.00D, respectively. Subjects had an age 21.96 ± 2.23 years [18–30] and mean spherical equivalent refraction M = −2.23 ± 1.50D [−0.75 to −5.50] with refractive astigmatism below −0.75D. Higher-order aberrations (HOA), glare formation (halo), high- and low-contrast LogMAR visual acuity (VA), and contrast sensitivity function (CSF) was measured under monocular conditions.Results All individual terms of HOA and total root mean square from 3rd to 8th order increased significantly with the 3 test lenses compared to control. Between test lenses, Lens 1 increased significantly the higher HOA compared with Lens 2 and Lens 3. Halo size was significantly larger with test lenses compared with control, with Lens 1 showing the largest. VA under high-contrast conditions was similar for all lenses. Under low-contrast conditions, Lens 1 and Lens 2 performed significantly worse than control (Bonferroni post hoc correction, p < 0.001). CSF was below normal limits with Lens 1 for 3 and 6 cpd spatial frequency but was not significantly different between test lenses and control.Conclusions Lenses with larger stabilized areas for distance vision interfere less with VA and induce lower values of HOA and image degradation.
GLARE
Astigmatism
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Purpose: To investigate ocular higher order aberrations (HOA) and spherical aberration changes caused by an aspheric soft contact lens designed to reduce spherical aberration (SA) of the eye. Methods: Fifty subjects who have successfully experienced soft contact lenses were refitted with aspheric design (Soflens Daily Disposable: SDD, Bausch+Lomb) soft contact lens. Ocular higher order aberrations (HOA) and stand alone SA were measured and analyzed for a 4-mm pupil size using Wave-Scan Wavefront aberrometer (VISX, Santa Clara, CA, USA). High and low contrast log MAR visual acuity and contrast sensitivity function (CSF) were also measured under photopic and mesopic conditions (OPTEC 6500 Vision Tester). All measurements were conducted monocularly with an undilated pupil. Results: The RMS mean values for total HOA with SDD contact lenses were significantly lower than those at with unaided eyes (p) (p and , respectively under photopic and and , respectively under mesopic condition. Contrast Sensitivity Function (CSF) with SDD lenses under both photopic and mesopic conditions was and , respectively. Conclusions: The SDD contact lens designed to control SA reduced the total ocular HOA and SA of the eye, resulting in compensating for positive SA of the eyes. Thus, the optical benefits of the lens with SA control would be adopted for improving the quality of vision.
Mesopic vision
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Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE).
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Astigmatism
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ABSTRACT PURPOSE: To assess visual, optical, and fitting characteristics for wavefront-guided soft contact lenses produced for one habitual soft lens-wearing moderate keratoconic eye. METHODS: A process for production and evaluation of custom wavefront-guided soft contact lenses was developed. Wavefront aberrations were quantified with the COAS-HD wavefront sensor (Wavefront Sciences); soft contact lenses containing both high and low order aberrations were designed with custom software and produced using an ophthalmic lens lathe. Photopic high and low contrast logMAR visual acuity were recorded with the lens in place over an artificial 5-mm pupil and residual 2nd to 10th order root-mean-square (RMS) aberrations were analyzed overa 5-mm pupil. Comparisons were made to the eye's habitual to rie soft contact lens using t tests. RESULTS: Photopic high contrast values for habitual and final custom contact lenses for a 5-mm pupil were 0.07?0.06 and -0.08?0.05, respectively. Photopic low contrast values were 0.73?0.06 and 0.62?0.07, respectively. Habitual and final custom correction low order RMS over a 5-mm pupil were 2.08 and 0.34 ???, and high order RMS levels were 0.77 and 0.39 ??t?, respectively. CONCLUSIONS: The final custom contact lens showed 1.5 lines of improvement for photopic high contrast (P=. 03) and 1 line for photopic low contrast (P=. 11) over a 5-mm pupil compared to habitual correction. Low and high order aberrations were reduced by 84% and 50% over a 5-mm pupil, respectively. Further improvements in performance of custom lenses may be achieved with further wavefront iterations. [J Refract Surg. 2007;23:960-964.]
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This study investigated in-vivo changes of peripheral refraction with commercially available single vision and multifocal soft contact lenses, utilizing different designs and various corrective power values. Starting at the fovea, wave-front aberrations were measured up to 30o nasal retinal eccentricity, in 10o increments, using a commercially available Shack-Hartmann aberrometer. Three different types of contact lenses were fitted in an adult subject's right eye: Acuvue Oasys Single Vision (ASV), Proclear Multifocal D with 2.50 diopters (D) add power (PMD), and ArtMost SoftOK (SOK). Each lens type was fitted in corrective power values of -2.00 D, -4.00 D, and -6.00 D. Refractive errors were computed in power vector notation: The spherical equivalent (M), the Cartesian Jackson-Cross-Cylinder (J0), and the oblique Jackson Cross Cylinder (J45) from measured second order Zernike terms. Acuvue Oasys Single Vision lenses produced a slight myopic shift at 30o retinal periphery (-0.32 D ± 0.05) without significant differences between the various lens power values. Proclear Multifocal D lenses did not create clinically significant myopic shifts of at least -0.25 D. All SOK lenses produced clinically significant relative myopic shifts at both 20o (-0.61 D ± 0.08) and 30o (-1.42 D ± 0.15) without significant differences between the various lens power values. For all lens types and power values, off-axis astigmatism J0 was increased peripherally and reached clinical significance beyond 20o retinal eccentricity. The increased amount of off-axis astigmatism J0 did not show a significant difference for the same type of lenses with different dioptric power. However, at 30o retinal eccentricity, SOK lenses produced significantly higher amounts of off-axis astigmatism J0, compared with ASV and PMD lenses (SOK versus ASV versus PMD: -1.67 D ± 0.09, -0.81 D ± 0.07, and -0.72 D ± 0.15). Both ASV and SOK lenses showed no clinically significant differences in the amount of introduced astigmatic retinal image blur, with various lens power values. Proclear Multifocal D lenses showed a systematic increase of astigmatic retinal image blur with an increase of add power. At 30o retinal eccentricity, -6.00 D SOK lenses introduced 0.73 D astigmatic retinal image blur, while PMD and ASV lenses introduced 0.54 D and 0.37 D, respectively. In conclusion, relative peripheral refractions, measured in-vivo, were independent of the contact lenses central corrective power. The SOK contact lenses demonstrated a stronger capability in rendering relative peripheral myopic defocus into far periphery, compared to the other lens designs used in this study. This was accompanied by higher amounts of introduced astigmatic retinal image blur.
Astigmatism
Eccentricity (behavior)
Optical power
Subjective refraction
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Abstract Purpose To quantify the optical quality of various daily disposable contact lenses in vivo and to ascertain its variation in terms of wearing time by means of objective non‐invasive determination of wavefront patterns. Methods The crx1 adaptive‐optics system was used to measure the wavefront aberrations in 15 myopic eyes before and at 2‐h intervals after contact lens fitting, over a 12‐h wearing period. Seven types of contact lenses having different material, water content and lens design were evaluated in this study: D ailies T otal1, D ailies A qua C omfort P lus, P roclear 1 Day, 1‐Day A cuvue T ru E ye, 1‐Day A cuvue moist, S of L ens daily disposable and C lariti 1‐Day. The aberration data were analysed by fitting Z ernike polynomials up to the 5th‐order for 3 and 5‐mm pupils. The optical quality under each condition and at each point in time was described by means of the Root‐Mean‐Square ( RMS ) value of wavefront aberration, Modulation Transfer Function ( MTF ), Point Spread Function and cut‐off spatial frequency. Results A RMS increase was observed after contact lens fitting as well as over time, both for a 3‐mm and a 5‐mm pupil. Each type of lens induced a different amount of wavefront aberrations, which vary over time also in a different manner. Dailies Total1 showed the lowest RMS values both at baseline and at the end of the day. In addition, Dailies Total1 provided the best MTF out of all the contact lenses that were assessed. These observations were reflected in higher cut‐off spatial frequencies and visual resolution both at baseline and after 12 h of wearing time. Conclusions Aberrometry makes it possible to analyse accurately and in vivo the optical quality of contact lenses and to assess how lenses having different characteristics – such as material or water content – behave for different wearing times. These variations across contact lenses may result in differences in visual performance.
Optical transfer function
Root mean square
Point spread function
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Purpose. The aim of this study was to investigate the effect of contact lenses on the optical performance of the eye by measuring wavefront aberrations for the eyes with or without contact lenses. Method. A sensitive aberrometer was used to measure wavefront aberrations for 54 eyes in 27 subjects for three conditions: with no contact lens (non-CL), with soft-contact lenses (soft-CL) and with rigid gas permeable contact lenses (RGP-CL). The root mean square (RMS) value of the wavefront aberrations and Zernike aberrations were calculated. Results. A change in the RMS values of wavefront aberrations with CL wear was observed for every eye. The change in wavefront aberrations with CL wearing was found to vary substantially from individual to individual. Relative to the mean RMS value of the group for the non-CL condition, the mean RMS value was increased for the soft-CL condition and was significantly reduced for the RGP-CL condition. A significant increase in mean RMS for the soft-CL condition was found when astigmatisms were removed. Although soft-CL wearing resulted in significant increases in higher orders of Zernike aberrations (fourth, fifth, and higher), the RGP-CL condition led to a significant decrease in second-order Zernike aberrations. For the eyes with low wavefront aberrations in the non-CL condition, either soft-CL wearing or RGP-CL wearing results in increases in the RMS values. Conclusion. Contact lens wearing, either with soft lenses or the RGP lenses, causes changes in the wavefront aberrations of the eye. The changes in wavefront aberrations vary substantially from eye to eye. Although soft-CL wearing tends to induce more higher-order aberrations, RGP-CL effectively reduces the astigmatisms. Both soft-CL and RGP-CL induce more aberrations for the eyes that have low wavefront aberrations. The change in wavefront aberrations due to contact lens wearing may explain the changes in visual performance for contact lens wearers reported previously.
Root mean square
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【Objective】To investigate the effect of soft and rigid gas permeable (RGP) contact lenses on imageq uality in myopic eyes and to determine the mechanism of the progression of myopia controled by RGP.【Methods】Wave- front aberrations were tested on 40 myopic eyes of 20 subjects who had good corrected visual acuities using a subjective aberrometer. Every subject was measured without contact lenses, with soft contact lenses, and with RGP.【Results】The root of mean square (RMS) of the second and fourth order Zernike aberrations in patients with RGPwas significantly smaller than that without contact lenses (P 0.05). The RMS of the second, third, and sixth orderZernike aberrations in patients with soft contact lenses was significantly greater than that without contact lenses (P0.05). In myopia with astigmatism, the RMS of the second and fourth order Zernike aberrations in patients with RGPis significantly smaller than that without contact lenses (P 0.05). The RMS of fourth, sixth, and seventh orderZernike aberrations in the patients with soft contact lenses was significantly greater than that without contact lensesin myopia with astigmatism (P 0.05). 【Conclusion】 The subjects with RGP yielded significantly better optical quality than the soft contact lens. The mechanism that RGP of controling or reducing the progression of myopia in adolescent maybe via improving retinal image quality.
Astigmatism
Root mean square
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