Aspheric Contact Research Articles

비구면 콘택트렌즈 코아 몰드 제작용 새그 데이터 출력 프로그램 개발

비구면 콘택트렌즈 코아 몰드 제작용 새그 데이터 출력 프로그램 개발

Effeciency contact correction of hypermetropia in children of school-age in the distant term of caution

Objective – to study the affectiveness of contact correction of hypermetropia in school-age children in the long of observetion.Materials and methods. The study included 56 children (112 eyes) aged 6 to 16 years with hyperopic refraction and astigmatism, who used soft silicone hydrogel contact lenses to correct ametropia. In these patients, a study of visual acuity, objective and subjective clinical refraction, axial length of the eye, corneal thickness and diameter, keratometry, as well as phorometric data (accommodation, vergence, dispar areas of the oculomotor system and their interaction) in early and late observation periods. Results. When using contact correction in school-age children with hyperopia and hyperopic astigmatism, statistically significant after 3 years of observation there was an increase in uncorrected visual acuity by 85 % (t = 7.9; p <0.01), corrected visual acuity by 7 % (t = 7.4; p <0.01), keratometry in the weak meridian by 1 % (t = 6.1; p <0.01), by 1 % (t = 8.9; p <0.01) in the strong meridian, the thickness of the cornea in the central zone by 4 % (t = 4.6; p <0.01), as well as a decrease in the sphere equivalent by 38 % (t = 3,1; p <0,01), the amplitude of accommodation by 20 % (t = 5.8; p <0.01), the negative part of the relative accommodation by 20 % (t = 3.0; p <0.01), the positive part of the relative accommodation by 18 % (t = 3.5; p <0.01), excess accommodation response by 64 % (t = 7.2; p <0.01), foria by 33 % (t = 4.4; p <0.01), foria by close by 22 % (t = 2.8; p <0.01), the ratio of accommodation convergence to accommodation by 18 % (t = 3.1; p <0.01).Conclusions. As a result of 3-year observation of school-age children with hypermetropia in which correction was used by various optical methods, it was established that correction with soft silicone-hydrogel aspheric contact lenses is the most effective way to control this ametropia, which is confirmed by an increase in visual acuity, spheroequivalent indicators, as well as changes in the front surface of the cornea: an increase in thickness in the central zone, and an improvement in keratometry, as well as a positive effect on accommodation ability, muscle balance and stereoscopic vision.

Nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control contact lens.

A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.

Effect of Multiple Front Surface Aspheric Design Functional Contact Lenses on Accommodative Function and Visual Quality

Purpose : To compare the differences in visual quality and accommodative functions after wearing single and multiple front surface aspheric functional contact lenses in the twenties having sufficient accommodation. Methods : Thirteen subjects(21.38±0.65 years) were evaluated for visual acuity, contrast sensitivity, stray light, total higher order aberrations, spherical aberration, coma aberration, accommodative response, binocular accommodative facility and near point of accommodation after wearing two types of contact lenses, respectively. Results : There was no significant difference in visual acuity, contrast sensitivity, stray light, total high order aberration, spherical aberration and binocular accommodative facility. Coma aberration increased slightly in wearing multi front aspheric functional contact lenses at 4 and 5 mm pupil size(p=0.037). Accommodative response(p=0.006) and near point of accommodation(p=0.005) were significantly reduced and shorter in wearing multi front aspheric functional contact lens. Conclusion : There was no difference in visual quality in wearing multiple front aspheric functional contact lenses compared to in wearing single front aspheric contact lenses. But it is thought to be useful as a functional contact lens for young adults because it has the effect on reducing the accommodative burden.

To Evaluate the Efficacy and Safety of Aspherical Soft Contact Lens in Myopia Control

To Evaluate the Efficacy and Safety of Aspherical Soft Contact Lens in Myopia Control

Nonpupil adaptive optics for visual simulation of a customized contact lens.

We present a method for determining the deformable mirror profile to simulate the optical effect of a customized contact lens in the central visual field. Using nonpupil-conjugated adaptive optics allows a wider field simulation compared to traditional pupil-conjugated adaptive optics. For a given contact lens, the mirror shape can be derived analytically using Fermat's principle of the stationary optical path or numerically using optimization in ray-tracing programs. An example of an aspheric contact lens simulation is given to illustrate the method, and the effect of eye misalignment with respect to the deformable mirror position is investigated. The optimal deformable mirror conjugation position is found to be near the posterior corneal surface. Chromatic aberration analysis is also presented, and our findings indicate that the polychromatic simulation quality is similar to that of the monochromatic case, even though the mirror is a reflective component. The limitations of a single continuous surface deformable mirror to mimic a contact lens are outlined, with some recommendations for improving the quality of simulation.

Experimental investigation of accommodation in eyes fit with multifocal contact lenses using a clinical auto-refractor.

Multifocal or multi-zone contact lenses are increasingly being fit to young eyes in an attempt to control myopia progression. However, success in achieving this aim may depend on how much the eye accommodates. The purpose of the current work was to evaluate the ability of an open-field clinical autorefractor to measure on-axis refractive state and accommodation in eyes fit with multifocal contact lenses (CLs). Refractive state was measured with a Grand Seiko WAM-5500 autorefractor (www.grandseiko.com) and a clinical Shack-Hartmann Complete Ophthalmic Analysis System (COAS) aberrometer (www.wfsci.com) in subjects fit bilaterally with single vision aspheric contact lenses, centre distance, and centre near zonal multifocal CLs, and an experimental myopia control multi-zone bifocal CLs (MiSight). Autorefractor measurements were obtained when aligned with the pupil centre, pupil margin, and mid-periphery. Accuracy of refractive state measurements was evaluated using a fully presbyopic (62-year-old) dilated (pupil diameter = 7.1 mm) eye measured through known added spherical powers (trial lenses) of +1.00 D to +6.00 D. Refractive state and accommodation were measured for seven young myopic eyes (23.71 ± 2.87 years) with six target vergences ranging from -0.33 D to -5.00 D. Irrespective of the CL fitted, measured changes in refractive state of the calibration eye were within ≤0.25 D of the added sphere power and the slope (measured refractive state/trial lens power) was approximately -1.0 D/D for both Shack-Hartmann (COAS) aberrometer and Grand Seiko instruments. Also, the Grand Seiko data were highly repeatable (mean measurement standard deviation = 0.04 D) as long as measurements occurred at the same pupil location, but exhibited a hyperopic bias that increased to +1.00 D when eyes were fit with CLs containing significant negative spherical aberration. Centre and marginal refractive states could differ by >3.00 D due to the combined spherical aberration contained in the eye plus the different CL designs. Measured refractive states of young accommodating eyes also varied with measurement location in the pupil. The accommodation gains were similar at each pupil location, irrespective of contact lens design. With consistent sampling at the same pupil location, the open field Grand Seiko clinical autorefractor proved an effective tool for assessing the on-axis refractive state and accommodative responses of eyes fit with multi-zone bifocal and multifocal CLs.

20대의 단초점 및 비구면 중심 근용 멀티포컬 소프트 콘택트렌즈 교정 시 조절기능 및 안구운동 반응 비교

20대의 단초점 및 비구면 중심 근용 멀티포컬 소프트 콘택트렌즈 교정 시 조절기능 및 안구운동 반응 비교

Accommodative Behavior of Eyes Wearing Aspheric Single Vision Contact Lenses.

Wearing aspheric contact lenses adds significant amounts of negative spherical aberration (SA). Also, when accommodated and converged to near targets, pupil size shrinks and SA shift from positive to more negative direction. Interestingly, in this study, pupil miosis was fully or partially able to compensate for the additional accommodation-induced negative SA. The present study aims to examine the accommodative response characteristics of young eyes fit with aspheric single vision contact lenses (SVCLs) that add significant negative SA to the eye responding to a wide range of accommodation stimuli. Using a Shack-Hartmann aberrometer, the accommodation behavior in eight young adult eyes (mean age and spherical equivalent is 27.25 ± 2.05 years and -1.75 ± 1.80D, respectively) was measured while subjects fixated binocularly and monocularly 20/40 letter E, which were moved from 2 m to 20 cm (0.5 to 5D) in 0.25D steps. Using natural pupils, refractive state was defined using three standard criteria: the dioptric power that (1) minimized the root mean square error (minRMS), (2) best-fit paraxial, and (3) provided the peak image quality (peak IQ). Wearing aspheric lenses with negative SA shifts the mean SA of the unaccommodated eyes from +0.05 μm (eyes only) to -0.029 μm (eyes + SVCL) and increases the negative SA for the eye + lens when accommodating from -0.029 to -0.07 μm for natural pupils. Aberration changes with accommodation were attenuated by the accommodative pupil miosis, which reduced binocular viewing pupil diameters from 3.9 to 3.3 mm. This alteration of the typical SA levels by the aspheric SVCL did not prevent accurate accommodation (mean ± standard deviation accommodative lag under binocular viewing were -0.08 ± 0.12D, -0.38 ± 0.12D, and -0.26 ± 0.08D for paraxial, minRMS, and peak IQ, respectively). These data clearly show that aspheric contact lenses designed to correct some or all of the unaccommodated eye's positive SA do not interfere with accommodation.

Study on Injection Molding of Shell Mold for Aspheric Contact Lens Fabrication

This study aims to propose a method to reduce the shrinkage error of shell molds in the injection molding process. The shell molds are used for casting bi-aspheric soft contact lens with HEMA material. Moldex3D R13.0 is used to simulate and analyze the shrinkage of the front contact lens curve on the front shell mold in Z-axis direction. First, the design of experiment (DOE) method is applied to obtain the optimal setting parameters (melt temperature, injection velocity, and packing pressure). Amount of the shrinkage error is used to compensate the original design curve to improve the shrinkage error in the next simulations. The simulation result after compensation shows that the shrinkage error is reduced as 80.8%. The adding value to compensate the original design curve should be optimized to minimize shrinkage error. Result of this study can effectively improve the shrinkage error before fabricating the shell molds of the soft aspheric contact lens.

矫正近视和老视的非球面衍射型隐形眼镜

矫正近视和老视的非球面衍射型隐形眼镜

Wavefront Aberrations in Subjects Wearing Soft Aspheric Contact Lenses and Those Wearing Spherical Ones

Purpose: To measure the level of higher order aberrations (HOA) when wearing a soft aspheric contact lens (CL), compared to a spherical CL, in myopic subjects.
 Method: Fifteen myopic subjects aged 20-30 years were tested for the presence of dry eye. Aberrometry measurements were done without a contact lens as well as with a spherical CL and an aspheric CL. Root mean square error (RMS) of HOA, spherical aberration (SA) and coma were measured five times in an interval of 15 seconds without blinking for each of the 3 conditions.
 Results: Wearing a spherical CL produced a significant increase of SA and horizontal coma compared to an eye without a contact lens. When wearing an aspheric CL, there was a trend towards a smaller increase of these aberrations. However, the difference between both types of lens was not statistically significant. In terms of total HOA, these were higher when wearing the spherical CL, while they tended to be less with the aspheric CL. As for the variations between blinks, there was a similar increase in total HOA and individual modes with time for the three conditions.
 Conclusion : Wearers of aspheric CL seem to show a tendency towards smaller amounts of SA, horizontal coma and HOA in general in comparison with wearers of SCL. However, total HOA increases during a long interval between blinks, no matter the condition.

모노비전, 변형된 모노비전, 멀티포컬 콘택트렌즈로 교정 시 20대 성인의 조절기능 비교

Purpose: The purpose of this study was to compare the accommodative function of young adult in their 20s wearing monovision, modified monovision, and aspheric multifocal contact lenses at near task. Methods: Thirty young adults () were fitted with monovision, modified monovision (the application of single vision contact lenses and center-near low addition aspheric multifocal contact lenses), and aspheric center-near multifocal contact lenses. After wearing these modalities during a week for adaption, and after watching visual display at computer for inducing accommodative pressure for 1 hour. The following assessments of accommodative function were made: contrast visual acuity (VA) at distance and near; accommodative response; near accommodative facility; and negative relative accommodation (NRA)/positive relative accommodation (PRA). All measurements were carried out binocularly. Results: In binocular distance VA with contrast of 10%, monovision was the worst among the four modalities (p=0.005). In accommodative response at 1 m (1.00 D), monovision was the lowest (p

A randomized controlled clinical trial of the effectiveness and safety between aspherical and NUV soft hydrophilic contact lenses for myopia patients

Background The clinical effectiveness of soft corneal contact lens for correction of myopia has been confirmed.Theoretically, aspherical soft hydrophilic corneal contact lens has better visual qualify for myopic eyes, and the lenses have been applied widely.But abnormal tear film, even many cornea and conjuctiva diseases caused by soft contact lens have been reported, so the effectiveness and safety of aspherical soft hydrophilic corneal contact lens are worth concerning. Objective This clinical trail was to compare the effectiveness and safety between aspherical and NUV soft hydrophilic contact lens for myopic eyes. Methods A randomized, double-blind and controlled clinical study was performed under the approval of Ethic Committee of Qingdao Municipal Hospital and informed consent of each patient.One hundred and forty eyes of 70 myopic patients were enrolled in Qingdao Municipal Hospital from July to October, 2012.The subjects were randomized into the trial group and control group using random number table.Aspherical soft hydrophilic contact lenses were worn in the trial group and NUV soft hydrophilic contact lenses were worn in the control group.The characteristics of the lens surface, outcomes and the eye number in different scores of ocular signs and symptoms were assessed before and 15 minutes, 1 week, 2 weeks and 1 month after wearing lenses. Results The sores of humidity of anterior surface, the sediment in anterior and posterior surface are 0 in both lenses in various time points after wearing.The corrected visual acuity of all the subjects were ≥1.0.The eye number of 2-3 scores in various ocular signs was 0 in both groups, but the eye number of 1 score in palpebral conjunctival congestion and limbus congestion were more in the trail group than those in the control group in different time points (all at P 0.05). There was no eye for 2-3 scores of eye symptoms in both groups.The eye number for 1 score in foreign body sensation increased in the target-trail group compared to the control group at various time points (P=0.002, 0.006, 0.005, 0.005). However, there was no statistically significant differences in the eye number for 1 score in visual clearness and stability between the two groups at the follow-up duration (all at P>0.05). Conclusions Aspherical soft hydrophilic corneal contact lens has good outcomes in corrected visual acuity for myopia like NUV soft hydrophilic contact lens, but the wearing of aspherical soft hydrophilic corneal contact lens induces more ocular discomfortableness. Key words: Contact lenses, hydrophilic/adverse effects; Myopia; Aspherical lens; Effectiveness; Safety; Randomized controlled clinical trail

Efficacy of spherical aberration correction based on contact lens power

To investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses). Ocular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch+Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (-7.00 diopters (D), -5.00 D, -3.00 D, -1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone. For the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from -0.15 to -0.05 μm, for all lens powers except for the -1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at -7.00 D (p=0.040), -3.00 D (p=0.015), -1.00 D (p<0.001), +1.00 D (p=0.006), and +3.00 D (p<0.001) powers. An aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of -0.15 to -0.05 μm over a 6mm aperture.

61 Comparison of spherical aberration controland visual acuity with aspheric and spherical contact lens optics

61 Comparison of spherical aberration controland visual acuity with aspheric and spherical contact lens optics

Accommodation in young adults wearing aspheric multifocal soft contact lenses

The aim of the present project was to investigate accommodative behavior in young adults and adolescents fitted with an aspheric multifocal (center distance) contact lens with focus on evaluating whether these lenses can be an alternative treatment for subjects in which a reduced level of blur and thereby accommodation in near vision is aimed at. Twenty normal subjects aged between 21 and 35 years participated in the study. Aberrometry was perfomed using a Zywave™ aberrometer, first on the uncorrected eyes of all subjects, and again while the subjects wore a multifocal contact lens with a +1.00 add. A Shin-Nippon N Vision-K 5001 Autoref-Keratometer was used to measure accommodative response with two different refractive corrections: (1) habitual spectacle correction only, and (2) habitual correction and a aspheric multifocal (center distance) contact lens. Four hours of adaptation to the lens was allowed. The lag when wearing only the habitual spectacles was compared with the lag while wearing both the habitual spectacles and the aspheric multifocal contact lens. The mean lag of accommodation for the subject group was 0.85 D (±0.57 SD) and 0.75 D (±0.52 SD) without and with the multifocal lens, respectively. Statistical analyses showed no difference in lag (t = 0.8479, p = 0.407) with and without the lens. In conclusion, young normal subjects do not relax accommodation when fitted with aspheric multifocal center distance lenses when the addition is +1.00. It is therefore unlikely that subjects with accommodative ability, in whom the treatment purpose is to reduce blur and thereby accommodation, can be effectively treated with such lenses.

Spherical aberration in relation to visual performance in contact lens wear

The aim of the present study was to evaluate changes in spherical aberration and their effect on visual quality (visual acuity and contrast sensitivity) in both distance and near with different non-custom-made contact lenses. A wavefront analyser was used to measure the aberrations in each subject's eyes uncorrected and with the contact lenses: a standard lens and two aspherical contact lenses. High-contrast visual acuity at distance was measured with Test-Chart 2000 (100% contrast) and at near with Sloan ETDRS Near Point chart (100% contrast). Low-contrast visual acuity at distance was measured with Test-Chart 2000 (10% contrast) and contrast measurements at near with Mars letter contrast sensitivity chart. Mean spherical aberration was positive for all pupil sizes in the uncorrected eye, residual spherical aberration was close to zero with the standard lens for all pupil sizes, whereas the two aspheric contact lenses over-corrected spherical aberration. The changes in aberration were statistically significant (p < 0.05) with all lenses. No significant difference could be detected between trial frame correction, spherical and aspherical soft contact lens designs with respect to visual quality. This was the case for both distance and near. The results are in line with previous studies and indicate that non-custom-made spherical aberration control contact lenses have little effect on visual quality as defined in this study.

Poster 26: Visual Outcomes Associated With Aspheric and Non-Aspheric Silicone Hydrogel Lenses

To investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses).Ocular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch + Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (−7.00 diopters (D), −5.00 D, −3.00 D, −1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone.For the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from −0.15 to −0.05 μm, for all lens powers except for the −1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at −7.00 D (p = 0.040), −3.00 D (p = 0.015), −1.00 D (p < 0.001), +1.00 D (p = 0.006), and +3.00 D (p < 0.001) powers.An aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of −0.15 to −0.05 μm over a 6 mm aperture.

054 Presbytie et lentilles souples multifocales : évaluation aberrométrique et résultats

Evolution of presbyopic lens designs, frequent replacement of contact lenses (CL) lead us to fit successfully more than 80% of patients. Special presbyopic refraction and examination are required in order to select contact lenses as: objective refraction, minimal addition required, pupill size, dominant eye, lids, tears and biomicrospic evaluation. Simultaneous vision is the most used correction concept. Aspheric CL designs may increase depth of focus for current near activities. We present results obtained with aspheric CL fitting with near addition in the center. Achieved distance vision is excellent for the vast majority of patients, even for emmetropic ones. Near vision is good for current near activities and can possibly be increased easily in some cases with somewhat plus power on the non dominant eye. Vision quality, evaluated by aberrometry, shows a very light increase of preexistant high order aberrations and few modifications concerning spherical aberrations. These results explain the rate of success of these CL, mainly in distance vision. In case of unsatisfactory results, aberrometry is a usefull tool to evaluate patient's initial high order aberrations and to select CL which are not likely to worsen this pre-existing abnormality.