Residual Spherical Aberration Research Articles

Improving retinal imaging by corneal refractive index matching

Imaging the retina at high resolution requires a dilated pupil, which in turn exposes more corneal irregularities. We diminish the optical errors of the cornea by refractive index matching. Lens-fitted goggles were used for corneal immersion, to reduce its aberrations, while keeping the ocular power. An additional aspheric plate reduced the residual ocular spherical aberration. A comparison of the index-matching-based retinal images with those acquired directly shows resolution improvement for subjects with normal extent of ocular aberrations. A simulation of the point spread function, obtained from an averaged ocular and corneal wavefront error, also reveals substantial improvement when using corneal index matching. The demonstrated improvement using index matching may enable further improvement of current retinal imaging techniques or relaxing requirements for active ocular aberration correction.

Effect of pupil size on residual wavefront aberration with transition zone after customized laser refractive surgery

The analysis of the change in residual wavefront aberrations after laser refractive surgery is important for the development of visual correction technology. Based on the ablation profile for wavefront-guided refractive surgery including optical zone and transition zone, the effect of pupil size on residual wavefront aberrations was studied. The research revealed that the optical zone to pupil ratio had a significant influence on the residual wavefront aberrations. The residual spherical aberration and coma were obviously larger than other individual Zernike higher-order terms when pupil diameter was larger than the optical zone size, and they increased rapidly as the pupil size increased. In addition, when the ablation zone diameter was kept constant, the residual higher-order aberrations increased rapidly as the blend coefficient increased for a 6 mm or 7 mm pupil. Furthermore, the residual higher-order aberrations with treatment decentration were distinctly larger than those without decentration. In the achievement of the best postoperative visual performance, the design of ablation profile played a crucial role in decrease of the residual wavefront aberrations after refractive surgery, especially optical zone size and the ablation pattern of transition zone.

Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system

To measure the impact of corneal aberrations on the through-focus image quality of presbyopia-correcting intraocular lenses (IOLs) using an adaptive optics IOL metrology system. Flaum Eye Institute, University of Rochester, Rochester, New York, USA. Experimental study. An adaptive optics IOL metrology system comprising a model eye, wavefront sensor, deformable mirror, and an image-capturing device acquired through-focus images of a letter chart with 3.0 mm and 5.0 mm pupil diameters. The system was used to induce corneal astigmatism and higher-order aberrations (HOAs) in previously measured pseudophakic presbyopic eyes. A single-optic accommodating IOL (Crystalens HD (HD500), an apodized (Restor +3.0 diopter [D] SN6AD1) and full-aperture (Tecnis ZM900) diffractive multifocal IOL, and a monofocal IOL (Acrysof SN60AT) were evaluated. Image quality was quantified using the correlation-coefficient image-quality metric. The single-optic accommodating IOL and monofocal IOL performed similarly; however, with a 3.0 mm pupil, the former had better intermediate (1.50 D) image quality. The multifocal IOLs had bimodal through-focus image quality trends. Corneal astigmatism reduced through-focus image quality and depth of focus with all IOLs; however, the multifocal IOLs had the most severe decline in depth of focus. Ocular spherical aberration had the strongest impact on image quality when typical pseudophakic corneal HOAs were present. The uncorrected corneal astigmatism and HOAs in pseudophakic eyes significantly affected through-focus performance of presbyopia-correcting IOLs. Although multifocal IOLs significantly increased depth of focus, this benefit diminished when more than 0.75 D astigmatism remained uncorrected. Residual ocular spherical aberration had a significant effect on image quality in the presence of other corneal HOAs.

Depth of Focus Through Different Intraocular Lenses in Patients With Different Corneal Profiles Using Adaptive Optics Visual Simulation

To evaluate the depth of focus with monofocal intraocular lenses (IOLs) in patients with different corneal profiles using adaptive optics (AO) visual simulation. An AO visual simulator (crx1, Imagine Eyes) was used to simulate the aberration pattern of three monofocal IOLs (Acrysof IQ SN60WF [Alcon Laboratories Inc]; Akreos Adapt AO [Bausch & Lomb]; and Triplato [AJL Ophthalmic]) of different optic designs. Five groups were considered: patients without any corneal refractive surgery (normal cornea group) and with prior low and high myopic and hyperopic ablations (low myopic ablation, high myopic ablation, low hyperopic ablation, and high hyperopic ablation groups). Defocus curves for all situations were measured, with the target being moved from -5.00 to +2.50 diopters (D) in 0.25-D steps, and visual acuity was measured at all vergences. Ten eyes from 10 patients were evaluated. The higher residual spherical aberration (SA) for all IOLs was obtained for the high myopic ablation group and the most negative residual SA was obtained for the high hyperopic ablation group. The best compromise between distance visual and depth of focus for the normal cornea, low myopic ablation, and high myopic ablation groups was obtained with the aspheric designs, whereas the best results for the low hyperopic and high hyperopic ablation groups were obtained with the spherical IOL. The results of this study suggest that the better compromise between distance visual acuity and depth of focus with the three IOLs and the different corneal profiles relies on a certain amount of positive SA. Above a certain limit of residual SA (positive or negative), visual acuity decreases at all vergences, worsening the depth of focus.

Visual simulation through different intraocular lenses using adaptive optics: Effect of tilt and decentration

To analyze visual quality differences between intraocular lenses (IOLs) and assess the impact of IOL decentration and tilt on visual quality. University of Valencia, Valencia, Spain. Cohort study. The crx1 adaptive optics visual simulator was used to simulate the wavefront aberration pattern of 2 commercially available aspheric aberration-correcting IOLs (Acrysof IQ SN60WF and Tecnis ZA9003) and 2 spherical IOLs (Akreos Adapt and Triplato) in 5 situations: centered, decentered 0.2 mm and 0.4 mm, and tilted 2 degrees and 4 degrees. Monocular distance visual acuity at 100%, 50%, and 10% contrast and the depth of focus were measured. Ten eyes of 10 patients were evaluated. When the IOLs were centered, there were no differences in visual acuity between the 4 IOLs at any contrast. The aberration-correcting IOLs were more sensitive to tilt and decentration than the spherical IOLs; Tecnis ZA9003 IOL was the most sensitive to decentration and the Acrysof IQ SN60WF IOL was the most sensitive to tilt. Higher residual spherical aberration slightly improved depth of focus and the tolerance to defocus. The results in this study suggest that the aspheric aberration-correcting and spherical IOLs provided comparable visual quality when centered in eyes in which the corneal higher-order aberrations are those of the average of the human cornea. Tilt and decentration of the IOLs had an impact on visual quality, with aberration-correcting IOLs having a greater effect than the spherical IOLs.

Effect of interaction of macroaberrations and scattered light on objective quality of vision in pseudophakic eyes with aspheric monofocal intraocular lenses

To assess the impact of wavefront ocular aberrations on objective vision quality and depth of focus in pseudophakic patients. University Hospital Bretonneau of Tours, Francois Rabelais Medicine Faculty of Tours, France. Cohort study. Consecutive eyes having implantation of an aspheric monofocal intraocular lens (IOL) (Acri.Smart) were studied. Aberrometry measurements were performed under mesopic conditions with a 6.0 mm pupil using a Wavescan aberrometer. Objective evaluation of optical vision quality was performed using the Optical Quality Analysis System II. The 3 measurements were the modulation transfer function values (MTF cutoff); objective depth of focus, which was computed as the focus range at which Strehl ratio did not fall below 50% of the maximum; and the objective scatter index. Fifty-four eyes (30 patients) were enrolled. Six months postoperatively, MTF cutoff values were increased with decreasing total ocular spherical aberration, ocular trefoil, and 2nd-order astigmatism (P<.05). Objective depth of focus was positively correlated with 2nd-order astigmatism (r(2) = 0.171, P<.001) and total spherical aberration (r(2) = 0.091, P=.028). Objective scatter was more beneficial for depth of focus, with a significantly positive correlation with this parameter (r(2) = 0.28, P=.002), than compromising of optical quality (no significant correlation with MTF measurements in same multiple regression analysis). Three ocular aberrations (2nd-order astigmatism, trefoil, spherical aberration) seemed to interact with objective contrast sensitivity and depth of focus, whereas residual spherical aberration exerted opposite effects on image quality in individual patients.

Clinical Study of Customized Selected Aspherical Intraocular Lens Implants

Aims: To compare if there is an improvement in visual functions with age-related cataracts between patients receiving customized selected aspherical intraocular lens (IOL) implants and patients randomly assigned lenses. Methods: Ninety-four patients (94 eyes) with age-related cataracts were placed in experimental group or a group receiving randomly assigned (RA) lenses. All patients were undergone Pentacam corneal spherical aberration measurement before surgery; The targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm in experimental group. Patients with a corneal spherical aberration ≤ 0.3 μm were implanted with a zero-spherical aberration advanced optics (AO) aspherical intraocular lens and patients with an aberration 0.3 μm received a Tecnis ZA9003 aspherical lens. RA patients were randomly implanted with an AO lens or a Tecnis ZA9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and LogMAR vision were measured. Results: Statistical analysis on LogMAR vision showed no significant difference between two groups (P = 0.308). The post-surgical total spherical aberration was 0.120 ± 0.097 μm and 0.158 ± 0.152 μm in the experimental and RA groups, respectively (P = 0.08). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P = 0.00; P = 0.04; P = 0.01). The mesopic with glare contrast sensitivity in the RA group at a spatial frequency of 18 c/d was also significantly higher vs. the RA group (P = 0.02). Conclusion: Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical intraocular lens implants improved mesopic contrast sensitivities and mesopic with glare contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical intraocular lens implants.

Spherical aberration: Friend or Foe ?

AbstractPurpose To determine the level of residual spherical aberration that gives the best objective and subjective quality of image after cataract surgery with intraocular lens (IOL) implantation.Methods Six months after microincision (1.8 mm) cataract surgery with aspheric IOL implantation, total aberrations were computed using a Wavescan aberrometer. The modulation transfer function (MTF), Strehl ratio, and objective index of scattering were measured using the Objective Quality Analysis System. Objective depth of focus was computed as the focus range at which the Strehl ratio did not fall below 50% of maximum. Subjective depth of focus was calculated as the difference between the vergence of the punctum remotum and that of the punctum proximum.Results Thirty patients (54 eyes) were evaluated. The MTF cutoff values were higher with decreasing total ocular spherical aberration (r = 0.56; P&lt;.05). Objective and subjective depth of focus were positively correlated with total spherical aberration (r = 0.26 and r = 0.46, respectively; P&lt;.05).Conclusion A final spherical aberration of zero obtained by compensation of IOL asphericity gave the greatest improvement in objective quality of vision and better MTF contrast. However, a final target ocular spherical aberration between 0.07 μm and 0.10 μm should be considered to be the best compromise between subjective depth of focus and objective contrast sensitivity.

Effect of residual ocular spherical aberration on objective and subjective quality of vision in pseudophakic eyes

To determine the level of residual spherical aberration that gives the best objective and subjective quality of image after cataract surgery with intraocular lens (IOL) implantation. Department of Ophthalmology, CHU Bretonneau, Tours, France. Cohort study. Six months after microincision (1.8 mm) cataract surgery with aspheric IOL implantation, total aberrations were computed using a Wavescan aberrometer. The modulation transfer function (MTF), Strehl ratio, and objective index of scattering were measured using the Objective Quality Analysis System. Objective depth of focus was computed as the focus range at which the Strehl ratio did not fall below 50% of maximum. Subjective depth of focus was calculated as the difference between the vergence of the punctum remotum and that of the punctum proximum. Thirty patients (54 eyes) were evaluated. The MTF cutoff values were higher with decreasing total ocular spherical aberration (r = 0.56; P < .05). Objective and subjective depth of focus were positively correlated with total spherical aberration (r = 0.26 and r = 0.46, respectively; P < .05). A final spherical aberration of zero obtained by compensation of IOL asphericity gave the greatest improvement in objective quality of vision and better MTF contrast. However, a final target ocular spherical aberration between 0.07 μm and 0.10 μm should be considered to be the best compromise between subjective depth of focus and objective contrast sensitivity. No author has a financial or proprietary interest in any material or method mentioned.

基于哈特曼-夏克波前测量原理的焦距测量

A novel means of lens focal length measurement was proposed based on Hartmann-Shack principle of wavefront detection.Mathematical approaches of focal length measurement were deduced.In the experiments,laser sources with wavelength of 633 nm and 780 nm were separately used and focal length of three pieces of doublets were measured by the two wavelengths.The results show that the measured result can truly reflect the designed focal length by using 633 nm wavelength laser beam,which indicates that this measurement method is feasible and reliable.Meanwhile,the measured result by using 780 nm wavelength laser beam shows larger differences compared with its 633 nm counterpart,which reveals that this method can also be used to evaluate residual spherical aberrations,chromatic aberrations and manufacturing tolerance.

Influence of ocular longitudinal chromatic aberration on the selection of aspheric intraocular lenses

Polychromatic defocus could affect the optimal residual spherical aberration that could yield the best image quality for patients with intraocular lenses (IOLs). Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus. The maximum MTF volume occurred at + 0.05 μm of overall ocular spherical aberration. For 3 case studies, the optimal overall ocular spherical aberration was ~0.05 μm more positive with the contribution of polychromatic defocus than without it. Overall, the model indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.

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.

Postoperative wavefront analysis and contrast sensitivity of the multifocal RestorTM IOL versus the AcrylisaTM IOL

Abstract Purpose To compare visual acuity, total and high order wavefront aberrations (coma, spherical aberration, and other terms of high order aberration), and contrast sensitivity in eyes implanted with the multifocal Restore IOL versus the multifocal Acrylisa IOL. Methods Patients were divided in two groups: group 1 (8 patients, 16 eyes implanted with Restor) and group 2 (15 patients / 30 eyes implanted with Acrylisa). All eyes were targeted for emmetropia. Complete ophthalmological examination, including uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA) was performed. Contrast sensitivity evaluation,and wavefront analysis, were performed with the Imagine Eyes IRX3 wavefront aberrometer. Measurements with the IRX3 were performed in triplicate in order to verify the robustness of the data. Results All eyes in all groups had BSCVA &gt; or = 20/20 postoperatively. Measurements with the IRX3 were easily obtained. The triplicate measurements confirmed the robustness of the data. Mean total aberration root‐mean‐square (RMS) values and higher order aberrations (HOA) value were not significantly different between the two groups. Residual spherical aberration values were comparable in both groups and appeared inferior if to the ones previously obtained with non aspheric standard monofocal IOLs. Mean contrast sensitivity values were comparable in both groups. Conclusion The measurement of higher order aberrations in patients implanted with multifocal IOLs is easy and reproducible with the IRX3. There is no statistical difference between the values obtained in the 2 groups regarding RMS and HOA. Contrast sensitivity revealed similar values in both groups.

Custom selection of aspheric intraocular lenses after wavefront-guided myopic photorefractive keratectomy

To determine the optimum amount of spherical aberration in an intraocular lens (IOL) to maximize optical quality after previous wavefront-guided myopic photorefractive keratectomy (PRK). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Aspheric IOL implantation was simulated in 102 eyes of 77 patients. The amount of spherical aberration in the IOL was varied to produce residual ocular spherical aberration from -0.50 to +0.50 microm. Using ZernikeTool software, the polychromatic point-spread function with Stiles-Crawford effect was calculated for residual ocular higher-order aberrations (HOAs) (3rd to 6th order) for 4.0 mm and 6.0 mm pupils and defocus of 0.00 diopter (D), -0.50 D, and +0.50 D. The IOL spherical aberration at which maximum image quality was achieved was determined. Stepwise multiple regression analysis was performed to assess the predictors of optimum IOL spherical aberration. With 0.00 D, -0.50 D, and +0.50 D defocus, respectively, the mean optimum IOL spherical aberration (6.0 mm) ranged from -0.49 to -0.42 microm, -0.22 to -0.18 microm, and -0.75 to -0.64 microm (6.0 mm pupil) and from -0.34 to -0.20 microm, +0.08 to +0.44 microm, and -1.12 to -0.83 microm (4.0 mm pupil). Of the Zernike terms that significantly predicted optimum IOL spherical aberration, 4th-order spherical aberration Z(4,0) made the greatest contribution, followed by the 6th-order spherical aberration Z(6,0). The amount of IOL spherical aberration producing the best image quality after previous myopic wavefront-guided PRK varied widely and could be predicted based on the full spectrum of corneal HOAs.

Aspheric intraocular lenses: effect of residual spherical aberration on objective quality of vision

Abstract Purpose To assess the impact of residual spherical aberration (SA) on objective quality of vision in pseudophakic patients. Methods 15 patients (25 eyes) were divided into 2 groups: 13 eyes received an aspherical AcriSmart36A® generating a negative SA, 12 eyes received a zero‐aberration AcriSmart46LC®. Postoperative evaluations were conducted 6 months after a 1.8mm micro incision cataract surgery. Aberrometric measurements were done for a standardized pupil size of 5 mm in mesopic conditions using Wavescan Aberrometer®. Modulation Transfer Function (MTF), Strehl ratio and depth of field were measured with Objective Quality Analysis System®. Results Best corrected 100% LogMar distance visual acuity (BCVA) was similar in both groups (p=0.89). 20% and 9% BCVA was increased in 36A® group (p=0.009 and 0.005). Mesopic contrast sensitivity was better and total spherical aberration were significantly less with 36A® IOL(SA=0.075±0.05 μm with 36A® and 0.20±0.05 μm with 46LC®,p=0,0002). Coma and trefoil were not different between the two groups (p&gt;0,05). 36A® induced better image quality with an average MTF of 32.7±9.6 c/deg with 36A® and 23.8±8.1 c/deg with 46LC®, p=0.0002. The 36A® group had 1D less depth of focus than the 46LC® group at 6 months : respectively 1.3±0.59D and 2.27±0.63D. For the whole population, depth of focus appeared to be correlated with SA (r2=0.28, p=0.02) and with trefoil (r2=0.49, p=0.0009). Conclusion While reducing total ocular SA, aspheric IOLs improved mesopic contrast sensitivity, quality of vision with greater MTF values. Reduction of aberrations may be responsible for reduced depth of focus with 36A® IOLs. However, residual trefoil aberrations may be advantageous for depth of focus and reading ability.

Recent developments in aspheric intraocular lenses

Aspheric intraocular lenses (IOLs) were designed to improve functional vision on the assumption that reducing ocular spherical aberration would lead to improvements in contrast sensitivity. Although this has largely been confirmed by many studies, several recent studies have reported no difference in contrast sensitivity or in patient preference. The purpose of this article is to review recent findings and offer explanations for these apparently contradictory results. Studies report excellent and reliable visual acuity with aspheric IOLs. Compared with spherical IOLs, spherical aberration is either lower, or entirely eliminated, depending on the IOL implanted, and most earlier studies report a corresponding improvement in contrast sensitivity and various aspects of functional vision. Articles appearing in the past 12-18 months vary, with some reporting marked improvements in contrast sensitivity and patient preference, and others finding no difference either in functional vision or subjective evaluation. Possible reasons include suboptimal targeting of residual spherical aberration, insufficient follow-up for differences to become apparent and physiological limitations on perceived visual quality. Aspheric IOLs offer improved functional vision to patients but may need to be better targeted. As a growing number of younger patients undergo clear lens extraction, differences in visual quality may become better appreciated.

Spherical aberration in contact lens wear

The aim of the present studies was to investigate the effect on spherical aberration of different non custom-made contact lenses, both with and without aberration control. A wavefront analyser (Zywave, Bausch & Lomb) was used to measure the aberrations in each subject's right eye uncorrected and with the different contact lenses. The first study evaluated residual spherical aberration with a standard lens (Focus Dailies Disposable, Ciba Vision) and with an aberration controlled contact lens (ACCL) (Definition AC, Optical Connection Inc.). The second study evaluated the residual spherical aberrations with a monthly disposable silicone hydrogel lens with aberration reduction (PureVision, Bausch & Lomb). Uncorrected spherical aberration was positive for all pupil sizes in both studies. In the first study, residual spherical aberration was close to zero with the standard lens for all pupil sizes whereas the ACCL over-corrected spherical aberration. The results of the second study showed that the monthly disposable lens also over-corrected the aberration making it negative. The changes in aberration were statistically significant (p<0.05) with all lenses. Since the amount of aberration varies individually we suggest that aberrations should be measured with lenses on the eye if the aim is to change spherical aberration in a certain direction.

The relationship between the treatment zone diameter and visual, optical and subjective performance in Corneal Refractive Therapy™ lens wearers1

To investigate the stability of the treatment zone (TZ) size during Corneal Refractive Therapy (CRT) over 4 weeks of lens wear, and to determine the relationship between TZ diameter and visual, optical and subjective performance. Twenty-three myopic subjects wore CRT lenses overnight and removed their lenses on awakening. Visual Acuity (VA), subjective vision, refractive error, aberrations and corneal topography were measured at baseline, immediately after lens removal on the first day and 14 h later, and these measurements were repeated on days 4, 10 and 28. The TZ including the central flattened zone (CFZ) and the annular steepened zone (ASZ) was demarcated by the change in corneal curvature from negative to positive and vice versa, using the tangential difference map from the Atlas corneal topographer. After overnight CRT lens wear, the central cornea flattened and the mid-periphery steepened (both p < 0.001). After 4 weeks of lens wear, the CFZ (+/-SE) increased from 3.41 +/- 0.09 mm on day 1 morning to 3.61 +/- 0.07 mm on day 28 morning and the diameter of the ASZ increased from 8.17 +/- 0.16 mm (day 1 morning) to 8.85 +/- 0.14 mm (day 28 morning) (both p < 0.001). From day 10 onwards, the CFZ and ASZ diameter were stable in the morning (p > or = 0.404). Throughout the day, the CFZ became smaller during the first 10 days (all p < or = 0.022), whereas the ASZ diameter remained constant (all p > or = 0.079). There were positive correlations between the CFZ or ASZ and residual refractive error, subjective vision and spherical aberration. The CFZ was also correlated with astigmatism and higher order aberrations, and the ASZ was positively correlated with coma (r = 0.726 to 0.961, all p < or = 0.042). In addition, there were negative correlations between the CFZ or ASZ and total aberration and defocus and between the ASZ and VA (r = -0.707 to -0.953, all p < or = 0.050). The TZ changed during the first 10 days. Its size was associated with VA, residual refractive error, aberrations and subjective vision. The concept of a TZ is a useful metric of visual, optical and subjective performance in CRT lens wearers.

Aberration controll with contact lenses

Abstract Purpose: To investigate and compare the reduction in ocular aberrations with standard hydrogel contact lenses (i.e., lenses not designed to control aberrations) and with aberration controlled hydrogel and silicon‐hydrogel contact lenses. Methods: The aberrations with and without contact lenses were measured in 42 subjects between 20 and 37 years of age using a Zywave wave front sensor (B&amp;L). 22 subjects were fitted a standard contact lens and an aberration controlled hydrogel lens. The remaining 20 subjects were fitted aberration controlled silicon‐hydrogel lenses Results: With the standard lens the aberrations were controlled (i.e., close to zero) with a 4.0 mm pupil. Whereas, with both the aberration control lenses the residual spherical aberrations became negative. The reduction in aberrations differed significantly (p&lt;0.05) between all lenses. Conclusions: Since aberration controlled contact lenses in many subjects overcorrect the spherical aberrations when the pupil size is normal (~4.0 mm) we suggest measuring wave front aberrations in each patient both with and without contact lenses in order to achieve the desired effect.

Personalized correction of spherical aberration in cataract surgery

To compare contrast sensitivity after phacoemulsification with implantation of the Tecnis intraocular lens (IOL) between patients with a selected preoperative corneal spherical aberration and patients without a selected amount of aberration. Private practice, St. Catharines, Ontario, Canada. Thirty-three cataract patients were divided into 2 groups. The first group (n = 13) included consecutive patients with a spherical aberration of at least +0.33 microm measured with the Oculus Easygraph. Consecutive patients meeting the inclusion criteria (n = 20) were included in the second group. All patients had phacoemulsification with implantation of the Tecnis IOL. After 3 to 5 weeks, contrast sensitivity was measured by sinusoidal grating charts for distance under photopic (85 cd/m2) and mesopic (3 cd/m2) conditions with optical correction in place. Five standard spatial frequencies were tested. All surgical procedures and postoperative courses were uneventful. The IOLs were in the bag without decentration or tilt. The mean preoperative spherical aberration was +0.370 microm +/- 0.024 (SD) in the first group and +0.291 +/- 0.081 microm in the second group (P = .0010). Patients in the first group had better contrast sensitivity than those in the second group. Statistically significant differences were detected at spatial frequencies of 6.0 cycles per degree (cpd) and 12 cpd under photopic conditions (P = .0267 and P = .0215, respectively) and mesopic conditions (P = .0356 and P = .0217, respectively). The Tecnis IOL has a negative spherical aberration of -0.27 microm. Targeting for a postoperative mean residual spherical aberration of approximately +0.10 microm by selecting patients according to their preoperative spherical aberration resulted in better contrast sensitivity.