High-order aberrations in pseudophakia with different intraocular lenses

Long-Term Evaluation of Visual Outcomes and Patient Satisfaction after Binocular Implantation of a Bioanalogic Lens

Purpose

Long-term evaluation of the visual refractive outcomes and the quality of life after implantation of the WIOL-CF (Medicem, Czech Republic) in both eyes.

Design

retrospective, nonrandomized noncomparative case series.

Methods

50 eyes of 25 patients, including 11 women (44%) and 14 men (56%). The age range of the patients was 38 to 77 years (mean age 55.48 ± 10.97 years). All patients underwent bilateral implantation of the WIOL-CF. Exclusion criteria were previous ocular surgeries except for cataract surgery and refractive lens exchange, irregular corneal astigmatism of >1.0 diopter, and ocular pathologies or corneal abnormalities. Postoperative examinations were performed at 14 days and 3, 6, 12 months of surgery; the last follow-up was between 24 and 36 months after the procedure. All exams included manifest refraction, monocular uncorrected visual acuity (UCVA) and distance-corrected visual acuity (DCVA) in 5 m (Snellen), monocular uncorrected visual acuity in 70 cm and 40 cm (Jeager) and binocular UCVA, DCVA in 5 m, 70 cm, and 40 cm, binocular contrast sensitivity (CS) under photopic conditions, binocular defocus curves, high-order aberrations, quality-of-vision VF-14 questionnaire, and spectacle independence.

Results

Significant improvement in monocular visual acuity at all distances was demonstrated; the mean postoperative spherical equivalent was 0.32 ± 0.45D. The postoperative means of binocular distance UCVA and BCVA were also improved (p < .001) and so were the mean uncorrected intermediate VA (2.053 ± 1.268) and near uncorrected VA (2.737 ± 1.447). There was a significant improvement in contrast sensitivity at all spatial frequencies and higher-order aberration, compared to preoperative results.

Conclusions

The evaluation of a WIOL-CF showed good distance, intermediate, and near visual acuity. Contrast sensitivity increased after surgery in all spatial frequencies. Patient satisfaction was high despite some optical phenomena. The rate of postoperative spectacle independence also turned out high. Financial Disclosure. No author has a financial or proprietary interest in any material or method mentioned.

Recent advances in measurement of monochromatic aberrations of human eyes

The field of aberrations of the human eye is moving rapidly, being driven by the desire to monitor and optimise vision following refractive surgery. It is important for ophthalmologists and optometrists to have an understanding of the magnitude of various aberrations and how these are likely to be affected by refractive surgery and other corrections. In this paper, I consider methods used to measure aberrations, the magnitude of aberrations in general populations and how these are affected by various factors (for example, age, refractive error, accommodation and refractive surgery) and how aberrations and their correction affect spatial visual performance.

Optical aberrations, accommodation, and visual acuity with a bioanalogic continuous focus intraocular lens after cataract surgery

Purpose

To evaluate the visual outcomes, pseudoaccommodation, and wavefront aberrometry after implantation of Wichterle IOL-Continuous Focus (WIOL-CF^®, Gelmed International, Kamenne Zehrovice, Czech Republic) by i-Trace aberrometry.

Methods

In this retrospective interventional case series study, after cataract surgery with implantation of accommodative WIOL-CF^®, the patients were evaluated with i-Trace aberrometer for measurement of modulation transfer function (MTF), point spread function (PSF), total aberrations, higher order aberrations (HOAs) at far and near and pseudoaccommodation. The pre and postoperative visual acuity at near and distance were also measured.

Results

Forty eyes of 20 patients (aged 40-77 years) were enrolled in this study with mean follow-up time of up 13.10 ± 5.52 months. The mean logMAR corrected distance visual acuity (CDVA) improved from 0.20 ± 0.14 preoperatively to 0.10 ± 0.09 at the last follow-up after surgery (P = 0.002). The results were 60% J1, 70% J2, 85% J3, 90% J4, 95% J5 and 100% for J6. The mean pseudoaccommodation, range of accommodation volume, and average of peak accommodation were -2.52 ± 1.56 diopters (D), 1.50 to 5.25 D and -3.25 ± 1.25 D, respectively. The mean MTF at 5 cycles per degree at far was 0.200 ± 0.10 and for near was 0.207 ± 0.10. PSF at far and near was 0.0002 and 0.001, respectively. The mean root mean square (RMS) value of HOAs; total, coma spherical aberration, trefoil, and secondary astigmatism were 1.08 ± 0.48 μm, 0.89 ± 0.45 μm, -0.33 ± 0.23 μm, 0.25 ± 0.17 μm, and 0.15 ± 0.13 μm for far and 0.88 ± 0.49 μm, 0.73 ± 0.46 μm, -0.25 ± 0.22 μm, 0.19 ± 0.16 μm and 0.11 ± 0.10 μm for near, respectively. There was a decrease in HOAs at near relative to far (P < 0.05).

Conclusion

WIOL-CF^® seems to be an acceptable accommodative intraocular lens (IOL) in terms of uncorrected near and distant visual outcomes, MTF and HOA.

Comparative study of visual function and ocular aberrations of two different one-piece designed hydrophilic acrylic intraocular lens

PURPOSE

To determine whether the aspherical IOL, Tecnis ZCB00, can improve the visual quality by measuring visual acuity, wavefront aberrations, and contrast sensitivity.

METHODS

It was a retrospective case series. Patients who underwent phacoemulsification cataract surgery were divided into two groups. One group (Group TC) was implanted with one-piece aspherical acrylic IOL (Tecnis ZCB00, AMO); the other (Group SA) was implanted with one-piece spherical acrylic IOL (Sensar AAB00, AMO). Eighty-eight eyes were selected into this study, among them 43 eyes in 26 male cases and 45 eyes in 29 female cases. Thirty-six eyes in 23 cases were in Group TC, and 52 eyes in 32 cases were in Group SA. Three months postoperatively, aberrations were analyzed with i-Trace visual function analyzer (Tracy Technologies, USA). Contrast sensitivities were measured with Takaci-CGT-1000 contrast glare tester (Seiko, Japan).

RESULTS

All the 88 eyes underwent phacoemulsification with intraocular lens implantation, without complications during or after surgery. Three months postoperatively, the uncorrected vision acuity in Group TC was significantly better than in Group SA (P = 0.007). At the pupil size of 5.0 mm, higher-order aberrations in Group TC were significantly higher than in Group SA (P = 0.02), especially the spherical aberration (Z ₄⁰ ) (P < 0.001); at the pupil size of 4.0 mm, Z ₄⁰ in Group SA was statistically higher than in Group TC (P < 0.001); at the pupil size of 3.0 mm, higher-order aberrations such as coma (Z ₃^-1,1 ) and trefoil aberration (Z ₃^-3,3 ) in Group SA were obviously higher than in Group TC (P = 0.01). In the low spatial frequency, the contrast sensitivity and the glare sensitivity in Group TC were significantly higher than in Group SA (P < 0.05).

CONCLUSIONS

By the short-term follow-up (3 months), the aspherical acrylic IOL can reduce the higher-order aberrations (especially the spherical aberration) and increase the contrast sensitivity to improve the visual performance.

Comparison of monochromatic aberrations in young adults with different visual acuity and refractive errors

PURPOSE

To compare the monochromatic aberrations in a large cohort of 20-year-old Australians with differing levels of visual acuity and explore the relationship between these aberrations and refractive error.

SETTING

Lions Eye Institute, Perth, Western Australia, Australia.

DESIGN

Cross-sectional analysis of a population-based cohort.

METHODS

Monochromatic aberrations were measured using a Zywave II wavefront aberrometer with natural pupils in a dark room. The logMAR corrected distance visual acuity (CDVA) was measured monocularly under normal illumination. Cycloplegic autorefraction was also performed.

RESULTS

The study enrolled 2039 eyes of 1040 participants. Data from 1007 right eyes were analyzed. The median CDVA and spherical equivalent were -0.06 logMAR (interquartile range [IQR], -0.10 to 0.00) and +0.25 diopters (D) (IQR, -0.38 to 0.63), respectively. The median 6.0 mm higher-order aberration (HOA) was 0.58 μm (IQR, 0.44 to 0.79). Coma-like aberrations and 3rd-, 4th-, and 5th-order HOAs were significantly different between subjects with a CDVA of -0.10 logMAR or better and those with a CDVA worse than -0.10 logMAR. Fourth-order aberrations Z(4,-4) (P=.024) and Z(4,-2) (P=.029) and 2nd-order aberration Z(2,0) (P<.001) differed significantly between myopic eyes, emmetropic eyes, and hyperopic eyes. Subjects with higher myopia had slightly higher total HOAs.

CONCLUSIONS

The HOAs in this population were marginally higher than previously reported values. The findings confirm there is a difference in monochromatic aberrations between different vision and refractive groups. Results in this study will benefit decision-making processes in the clinical setting.

Comparing the effect of two different intraocular lenses on optical aberrations in bilaterally operated eyes for cataract

OBJECTIVE

To assess high order and spherical aberrations results of hydrophobic acrylic AMO Sensar AR40E and hydrophobic acrylic Alcon AcrySof SA60AT intraocular lenses after implantation in cases with bilateral cataract.

METHODS

Cases diagnosed as bilateral cataract were included in the study and preoperative aberration measurements were recorded by using Nidek OPD SCAN-ARK 1000. Groups were created by implanting AMO Sensar AR40E to one eye of the patients, while Alcon AcrySof SA60AT into the other in a prospective and randomized manner. Aberration measurements were recorded after one and two months of surgery.

RESULTS

Overall, 40 eyes in 20 patients (11 women and 9 men) were included in the study. All patients underwent bilateral phacoemulsification surgery due to cataract. There were 20 eyes in both groups. Mean age was 62.4 (range: 31-82) years. There was no significant difference in aberrations recorded before surgery and one and two months after surgery in both groups. (p<0.05).

CONCLUSION

There was no difference among spherical intraocular lenses used in this study.

Effect of variation in derived corneal wavefront aberrations by calculation methods on intraocular lens selection

PURPOSE

To compare topographically derived corneal wavefront aberrations between the NIDEK Magellan corneal topographer with built-in software (NIDEK Co Ltd) and VOL-CT software (Sarver and Associates) and determine their effects on intraocular lens (IOL) choice based on spherical aberration profiles.

METHODS

Data were collected prospectively for 28 eyes without existing corneal disease prior to undergoing cataract surgery. Corneal higher order aberrations were calculated using Zernike polynomial expansions from topographic data and compared between the builtin NIDEK software and VOL-CT software.

RESULTS

Using two-tailed paired t tests, statistically significant (P<.05) differences were found between the two calculations at 4 mm for 4th order aberrations (NIDEK: 0.2005 μm, VOL-CT: 0.1202 μm) and 6th order aberrations (NIDEK: 0.0985 μm, VOL-CT: 0.0546 μm). Statistically significant differences were noted between the two calculations at 6 mm for 5th order aberrations (NIDEK: 0.2757 μm, VOL-CT: 0.1618 μm) and 6th order aberrations (NIDEK: 0.2641 μm, VOL-CT: 0.0920 μm). No statistically significant differences existed for 3rd order, spherical aberration, and total higher order aberrations. However, using spherical aberration-based IOL selection criteria, the ultimate IOL selection would have differed in 13 eyes if calculated using the NIDEK versus VOL-CT software.

CONCLUSIONS

Statistically significant differences were present in wavefront aberration calculations using the NIDEK versus VOL-CT software for 4- and 6-mm pupil sizes. These differences in spherical aberration could influence wavefront-optimized IOL selection for cataract surgery.

Visual and optical performance with hybrid multifocal intraocular lenses

During the past years, the wish to become independent of spectacles has been growing among cataract and presbyopic patients due to many factors, such as the increase in near visual demands, the aesthetic need for a spectacle-free image and ageing of refractive surgery patients, among others. This review assesses recently published studies that analyse visual and optical performance through different metrics of eyes implanted with multifocal intraocular lenses (IOLs), particularly hybrid IOL designs. The published evidence suggests that hybrid multifocal IOLs provide very good outcomes in a number of visual and optical performance parameters. Patients implanted with this type of IOL obtain a satisfactory full range of visual functions, including patients of particular characteristics such as highly ametropic or post-LASIK.

Problems testing diffractive intraocular lenses with Shack-Hartmann sensors

Shack-Hartmann wavefront sensors have found widespread application for testing ocular aberrations. These sensors provide an accurate map of the wavefront emerging from an eye in most cases. However, there is a growing class of patients with diffractive intraocular lenses that will potentially be measured incorrectly with Shack-Hartmann devices. We explore the pitfalls of measuring diffractive lenses with this technology.

Wavefront analysis of acrylic spherical and aspherical intraocular lenses

PURPOSE

To compare higher order wavefront aberrations in eyes implanted with acrylic aspherical intraocular lenses (IOLs) with a modified prolate anterior surface with conventional acrylic spherical IOLs by using the optical path difference method.

METHODS

In a nonrandomized parallel cohort investigation, 36 eyes of 31 patients implanted with aspherical IOLs (Tecnis ZA9003) and 37 eyes of 23 age-matched patients implanted with spherical IOLs (SENSOR AR40e) were evaluated with a wavefront analyzer (OPD-Scan II) preoperatively and 1 month after surgery. The higher order aberrations for a 4.0-mm pupil diameter were expanded into Zernike's polynomial expression. Coma aberration, spherical aberration, and total higher order aberrations were evaluated as root mean square values.

RESULTS

Postoperatively, coma and total higher order aberrations of spherical and aspherical IOLs significantly improved in both eyes. Spherical aberration improved in eyes with aspherical IOLs only (P < 0.01).

CONCLUSION

After implantation of acrylic aspherical IOLs, postoperative higher order aberrations were not necessarily lower than after implantation of acrylic spherical IOLs, but compared with levels following implantation of acrylic spherical IOLs, a significant reduction in spherical aberration was achieved.

Correlation of higher-order wavefront aberrations with visual function in pseudophakic eyes

AIM

To study the correlation between higher-order wavefront aberrations and visual function in eyes with a spherical monofocal intraocular lens (IOL), and to see if the aberrations differ between eyes that received different types of IOLs.

METHODS

One hundred forty-eight eyes of 148 patients who underwent phacoemulsification and implantation of one of five types of acrylic IOL were enrolled. At 1 month after surgery, ocular aberrations were measured using a Hartmann-Shack aberrometer and corneal aberrations were measured using videokeratography. In addition, the aberration of internal optics was determined by subtracting the corneal aberration from the ocular aberration. These aberrations were correlated with visual acuity and with contrast visual acuity under both photopic and mesopic conditions.

RESULTS

Ocular, corneal, and internal optic aberrations (total aberration, coma, and spherical aberration) were all correlated significantly with visual acuity, as well as with photopic and mesopic contrast visual acuity. The associations between internal optic aberrations and visual function tended to be stronger than were those of corneal aberrations. Furthermore, ocular aberrations differed significantly between eyes with the five different IOLs (P< or =0.0078). Specifically, the internal optic spherical aberration was markedly significantly different between eyes (P=0.0142), and the corneal coma showed a marginally significant difference (P=0.0421).

CONCLUSION

Ocular, corneal, and internal optic higher-order wavefront aberrations are correlated significantly with visual function in eyes with a spherical monofocal IOL. The spherical aberration of the internal optics and coma of the cornea vary between eyes with different types of IOL.

Clinical Ocular Wavefront Analyzers

PURPOSE

To provide a summary of the methods used by clinical wavefront analyzers and their historical, current, and future applications.

METHODS

Review of the literature and authors' experience with the various devices.

RESULTS

A wide range of clinical wavefront aberrometers, which use different principles, are available to clinicians and researchers.

CONCLUSIONS

Applications of wavefront analyzers in vision sciences range from assessment of refractive error, refractive surgery planning, evaluation of outcomes, optimization of contact lenses and IOL designs, evaluation of pathology relating to optical performance of the eye, and evaluation of accommodation alterations.

Theoretical Comparison of Aberration-correcting Customized and Aspheric Intraocular Lenses

PURPOSE

To assess the performance and optical limitations of standard, aspheric, and wavefront-customized intraocular lenses (IOLs) using clinically verified pseudophakic eye models.

METHODS

White light pseudophakic eye models were constructed from physical measurements performed on 46 individual cataract patients and subsequently verified using the clinically measured contrast sensitivity function (CSF) and wavefront aberration of pseudophakic patients implanted with two different types of IOLs. These models are then used to design IOLs that correct the astigmatism and higher order aberrations of each individual eye model's cornea and to investigate how this correction would affect visual benefit, subjective tolerance to lens misalignment (tilt, decentration, and rotation), and depth of field.

RESULTS

Physiological eye models and clinical outcomes show similar levels of higher order aberration and contrast improvement. Customized correction of ocular wavefront aberrations with an IOL results in contrast improvements on the order of 200% over the control and the Tecnis IOLs. The customized lenses can be, on average, decentered by as much as 0.8 mm, tilted > 10 degrees , and rotated as much as 15 degrees before their polychromatic modulation transfer function at 8 cycles/degree is less than that of the Tecnis or spherical control lens. Correction of wavefront aberration results in a narrower through focus curve but better out of focus performance for +/- 0.50 diopters.

CONCLUSIONS

The use of realistic eye models that include higher order aberrations and chromatic aberrations are important when determining the impact of new IOL designs. Customized IOLs show the potential to improve visual performance.

Changes of Ocular Higher Order Aberration in On- and Off-Eye of Rigid Gas Permeable Contact Lenses

PURPOSE

To investigate ocular higher order aberration (HOA) changes caused by rigid gas permeable (RGP) contact lens (CL) wear.

METHODS

Twenty-two eyes of 22 myopic patients and 14 eyes of 14 keratoconic patients who were fitted with an RGP CL were enrolled to examine ocular HOAs using a Hartmann-Shack wavefront sensor before and after RGP wear. Root mean square (RMS) values and Zernike coefficients in RGP-on and RGP-off eyes were compared for both myopic and keratoconic eyes, or between patient groups divided according to their prefitted total HOA value (RMS<0.33 microm or>or=0.33 microm in myopic eyes and RMS<0.46 microm or>or=0.46 microm in keratoconic eyes). All HOA values were recomputed for a 4-mm pupil for comparison purposes.

RESULTS

In keratoconic eyes, RGP CL changed the direction of vertical coma from -0.185 to 0.134 microm (p=0.024). In the low HOA myopic group, total HOA increased from 0.23 to 0.35 microm (p=0.006) by RGP CL wear, mainly due to increased coma aberration from 0.0951 to 0.2146 microm (p=0.006). The direction of vertical coma changed from the inferior to superior cornea in the low HOA group (p=0.020). In the high HOA keratoconic group, total HOA decreased from 0.54 to 0.36 microm (p=0.049), and the direction of the vertical coma changed from the inferior to superior cornea (p=0.049).

CONCLUSIONS

RGP CL wear may enhance or reduce HOA based on original existing ocular aberration mainly through directional changes in vertical coma.

Wavefront analysis and contrast sensitivity of aspheric and spherical intraocular lenses: a randomized prospective study

PURPOSE

To compare visual performance, total and high order wavefront aberrations (coma, spherical aberration, and other terms), and contrast sensitivity in 120 eyes implanted with one monofocal aspheric intraocular lens (IOL) and two spherical IOLs.

DESIGN

Randomized prospective study.

METHODS

Sixty patients were randomized to receive three IOL types: Alcon AcrySofIQ (40 eyes), AcrySofNatural (40 eyes), and advanced medical optic (AMO)Sensar (40 eyes). Complete ophthalmologic examination including uncorrected visual acuity (UCVA), best-spectacle corrected visual acuity (BSCVA), corneal topography, and wavefront analysis were performed preoperatively, 30 days, and 90 days postoperatively. Pelli-Robson chart test and functional acuity contrast testing (FACT-Optec6500) were performed approximately 50 days after surgery. Statistical analyses were performed using analysis chi(2), analysis of variance (ANOVA), and multiple comparisons Tukey test.

RESULTS

After 90 days, all eyes had postoperative BSCVA > or =20/32. The AcrySofIQ IOL showed statistically significant less induction of spherical aberration (P < .001) when compared with the AMOSensar and the AcrySofNatural IOLs. The AMOSensar presented significantly less spherical aberration then the AcrySofNatural (P < .05). The AcrySofIQ also had lower values of total and high-order aberration (HOA) (P < .05) when compared with the AMOSensar and the AcrySofNatural. The mean values of trefoil 9, coma, and HOA root mean square (RMS) decreased between one and three months (P < .001, P < .001, P = .023, P < .001, respectively) in all groups. Mean Pelli-Robson contrast sensitivity values in photopic condition were similar between the groups. The AcrySofIQ showed better results in 3cpd spatial frequency in mesopic condition using FACT-Optec 6500 (P = .008), although there were no statistical differences in photopic and mesopic with glare conditions.

Effect of total higher-order aberrations on accommodation in pseudophakic eyes

PURPOSE

To analyze the effect of total higher-order aberrations (HOAs) on the range of accommodation in pseudophakic eyes and the size of near-vision optotypes.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHODS

The study comprised 30 patients (44 eyes) who were diagnosed with cataract at Nara University of Medical Science Hospital and Municipal Oyodo Hospital. Inclusion criteria included no other eye disorder and a best corrected distance acuity of 20/20 or better 1 month after cataract surgery. All patients had small-incision phacoemulsification followed by in-the-bag implantation of a monofocal intraocular lens (SA60AT, Alcon). All incisions were self-sealing. Accommodation in pseudophakic eyes was measured by the lens-loading method in an examination room under constant illumination. Ocular HOAs were measured using the KR-9000PW Hartmann-Shack wavefront analyzer (Topcon).

RESULTS

The mean patient age was 75.8 years +/- 5.4 (SD) (range 64 to 83 years). The Pearson correlation coefficient (r) showed a significant positive correlation between the range of accommodation and Z7 (vertical coma) for a 4.0 mm pupil using the 1.0 near-vision optotype. There was a significant negative correlation between the range of accommodation and Z12 (spherical aberration) for a 4.0 mm pupil using the 1.0 near-vision optotype (r = .311, P = .040 for Z7;r = -.365, P = .015 for Z12). No other parameter was significantly correlated with the range of accommodation.

CONCLUSIONS

Measurement of accommodation in pseudophakic eyes by the lens-loading method using the 1.0 near-vision optotype showed that eyes with larger vertical coma aberrations achieved a larger range of accommodation. In contrast, eyes with larger spherical aberrations had smaller amounts of accommodation. The size of the near-vision optotype may affect accommodation analysis in pseudophakic eyes.

Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration

AIM

To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations.

METHODS

In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured.

RESULTS

In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations.

CONCLUSION

In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.

Contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes

PURPOSE

To investigate the relation between contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes.

STUDY DESIGN

Prospective observational case series.

PARTICIPANTS

Three hundred seven eyes of 161 normal subjects, ranging in age from 15 to 60 years (30.9+/-8.0 [mean +/- standard deviation]).

METHODS

Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer. The root-mean-square of the third- and fourth-order Zernike coefficients was used to represent comalike and spherical-like aberrations, respectively. We measured contrast sensitivity, low-contrast visual acuity (VA), and letter contrast sensitivity. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. Pupil diameter in a photopic condition was recorded using a digital camera.

RESULTS

Multiple linear regression analysis revealed that comalike aberration (P = 0.002) was significantly associated with AULCSF, but spherical-like aberration (P = 0.200), age (P = 0.185), and photopic pupil diameter (P=0.252) were not. Comalike aberration showed a significant correlation with low-contrast VA (P<0.001), but spherical-like aberration (P = 0.293), age (P = 0.266), and pupil diameter (P = 0.756) did not. Comalike aberration was found to be significantly associated with letter contrast sensitivity (P<0.001), but spherical-like aberration (P=0.082), age (P = 0.370), and pupil diameter (P = 0.160) were not.

CONCLUSIONS

In normal human eyes, comalike aberration of the eye significantly influences contrast sensitivity function.

Ocular aberrations after cataract surgery with hydrophobic and hydrophilic acrylic intraocular lenses

PURPOSE

To compare tilt and some higher-order aberrations (HOAs) in patients who had cataract surgery and implantation of 2 types of acrylic intraocular lens (IOL), the hydrophobic MA60AC (Alcon) or the hydrophilic XLSTABI (Ioltech).

SETTING

Fondation Ophtalmologique Adolphe de Rothschild, Department of Pr Hoang-Xuan, Paris, France.

METHODS

Sixty eyes were included in this study. Eyes in group 1 (n = 30) received the acrylic hydrophobic MA60AC IOL, and eyes in group 2 (n = 30) received the acrylic hydrophilic XLSTABI IOL. Optical aberrations were measured with Nidek OPD-Scan at least 1 month after cataract surgery for a 6.0 mm pupil diameter using a 6th-order Zernike polynomials decomposition.

RESULTS

In group 1, the mean root-mean-square (RMS) coefficient for the total higher aberration was 0.86 microm +/- 0.38 (SD). The mean RMS of the tilt, coma, trefoil, tetrafoil, spherical aberration, and secondary astigmatism was 0.81 +/- 0.45 microm, 0.38 +/- 0.30 microm, 0.55 +/- 0.18 microm, 0.13 +/- 0.23 microm, 0.30 +/- 0.13 microm, and 0.17 +/- 0.21 microm, respectively. In group 2, the mean RMS coefficient for the total higher aberration was 0.72 +/- 0.31 microm. The mean RMS of the tilt, coma, trefoil, tetrafoil, spherical aberration, and secondary astigmatism was 0.55 +/- 0.30 microm, 0.24 +/- 0.19 microm, 0.50 +/- 0.23 microm, 0.07 +/- 0.22 microm, 0.32 +/- 0.13 microm, and 0.14 +/- 0.14 microm, respectively. There was a statistical difference in aberrations between the 2 groups for the tilt and the coma aberrations (P<.05). There were more aberrations in the MA60AC IOL group.

CONCLUSIONS

The design of the IOL influenced ocular aberrations after cataract surgery. There were more tilt and coma aberrations in the MA60AC IOL group.

Star testing: a novel evaluation of intraocular lens optical quality

BACKGROUND

Despite the importance of optical quality of an intraocular lens (IOL) on visual outcomes following cataract surgery, objective data on their optical quality are not readily available, and manufacturing standards are industry regulated. The star test is a classic test of optical quality based on examination of the Airy disc and expanded diffraction rings of a point source of light, used mainly for telescope and microscope objectives.

METHODS

A physical model eye cell allowed star testing of IOLs under conditions similar to the optical environment in which they operate. 18 IOLs were tested and results compared to actual images produced by these lenses in the model eye cell. Quantitative measures of star testing performance were developed.

RESULTS

The optical performance of the IOLs varied, some performing very poorly. Most lenses (13/17) performed better in reverse orientation, while aberrations induced by the haptics of foldable IOLs were also detected. There was excellent correlation between actual images formed and star testing parameters.

CONCLUSION

Star testing IOLs was a novel biomedical application of a centuries old, inexpensive method. A concerning variation of optical quality was found, suggesting IOL optical performance data should be more readily available. Independent, authority mandated IOL optical quality standards should be developed, and results readily available to ophthalmologists.

A Comparison of Higher Order Aberrations Following Implantation of Four Foldable Intraocular Lens Designs

PURPOSE

To determine the higher order aberrations following implantation of four foldable intraocular lens (IOL) designs.

METHODS

One hundred twenty-two eyes were randomly assigned to undergo implantation with one of four foldable IOL designs--Collamer (STAAR Surgical, Monrovia, Calif), plate haptic silicone (STAAR Surgical), AcrySof (Alcon, Ft Worth, Tex), or the Sensar (Advanced Medical Optics, Santa Ana, Calif). All enrolled eyes underwent wavefront assessment using the Tracey Visual Function Analyzer (Tracey Technologies, Houston, Tex).

RESULTS

Preoperatively, no significant differences were noted in higher order aberrations between the four lens groups. No significant differences were noted among the plate haptic silicone, Sensar, or AcrySof lenses at 1 week or 1 month postoperatively, or among the Collamer, plate haptic silicone, or Sensar lenses, with regard to total higher order aberrations, although differences were observed in individual aberration terms. At 1 week and 1 month postoperatively, the Collamer IOL had significantly less higher order aberrations than the AcrySof lens (P < .01). Significantly less third and fourth order aberrations, coma, trefoil, spherical aberration, and tetrafoil were observed postoperatively with the Collamer than the AcrySof IOL. There were no parameters where the AcrySof had significantly less optical aberrations than the Collamer.

CONCLUSIONS

The Collamer IOL design is associated with fewer higher order aberrations than the AcrySof lens.

Postoperative Wavefront Analysis and Contrast Sensitivity of a Multifocal Apodized Diffrattive IOL (ReSTOR) and Three Monofocal IOLs

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 105 eyes implanted with 4 different types of intraocular lenses (IOLs) (1 multifocal apodized diffractive IOL and 3 monofocal IOLs).

METHODS

A prospective study comparing four types of IOLs (Alcon ReSTOR [50 eyes], Alcon Acrysof MA30AC [20 eyes], Alcon Acrysof SA60AT [20 eyes], and Mediphacos Acqua IOL [15 eyes]) was carried out. All eyes were targeted for emmetropia. Complete ophthalmological examination, including uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity (Pelli-Robson chart), and wavefront analysis, was performed 2 months postoperatively.

RESULTS

All eyes in all groups had BSCVA > or = 20/32 postoperatively. Mean total aberration root-mean-square (RMS) values were: 0.72 +/- 0.25 microm (ReSTOR), 0.94 +/- 0.26 microm (MA30), 0.84 +/- 0.23 microm (SA60), and 2.04 +/- 0.77 microm (Acqua). Mean higher order aberration values were: 0.35 +/- 0.15 microm (ReSTOR), 0.41+/- 0.12 microm (MA30), 0.43 +/- 0.13 microm (SA60), and 0.85 +/- 0.50 microm (Acqua). The Acqua IOL showed statistically significant more total and higher order aberrations when compared with the other IOLs (P < .05). The ReSTOR IOL showed statistically significant less induction of spherical aberration when compared to the monofocal IOLs (P < .05). Mean contrast sensitivity values were: 1.64 +/- 0.08 (ReSTOR), 1.72 +/- 0.08 (MA30), 1.70 +/- 0.07 (SA60), and 1.65 +/- 0.11 (Acqua).

CONCLUSIONS

Different types of IOLs resulted in measurably different postoperative higher order aberration patterns. The multifocal apodized diffractive IOL (ReSTOR) induced significantly less spherical aberration compared to the monofocal IOLs. Contrast sensitivity revealed better values with MA30 and SA60 IOLs when compared to ReSTOR. The integration of wavefront technology in evaluating pseudophakic patients represents a step towards better understanding and analyzing postoperative visual quality.

Limitations of Correcting Spherical Aberration With Aspheric Intraocular Lenses

PURPOSE

Aspheric intraocular lenses (IOLs) are deigned to correct spherical aberration in pseudophakic eyes. We predict the benefit from correcting spherical aberration based on simulations and aberrometry of pseudophakic eyes implanted with spherical IOLs.

METHODS

Ray tracing was performed through a model eye with an equi-biconvex spherical IOL and with a spherical aberration-correcting aspheric IOL. The IOLs were increasingly tilted and/or displaced, and the resulting transverse aberrations of 169 rays were transformed into Zernike coefficients for different pupil sizes. The benefit from correcting spherical aberration at individual esopic pupils was investigated by canceling C4(0) in the sets of Zernike coefficients for 41 eyes implanted with spherical IOL.

RESULTS

Both the model eye and the real eye data predict that age-related miosis reduces spherical aberration in the eye implanted with a spherical IOL to approximately 1/3 of the spherical aberration at a 6-mm pupil. A reduction of similar magnitude occurs when spherical aberration-induced non-paraxial defocus is corrected by a spectacle lens. For natural mesopic pupils, canceling the Zernike C4(0) coefficient improved the objective image quality at a rate similar to changing defocus by 0.05 diopters. Average decentration and tilt levels diminish the lead of aspheric IOLs over spherical IOLs, depending on the direction of decentration.

CONCLUSIONS

The benefit from correcting spherical aberration in a pseudophakic eye is limited for some or all of the following reasons: wearing glasses, age-related miosis, tilt and decentration of IOL, small contribution of spherical aberration to all aberrations, and intersubject variability.

Effect of tilt of 2 acrylic intraocular lenses on high-order aberrations

PURPOSE

To investigate the high-order aberrations (HoAs) in pseudophakia between 2 foldable acrylic intraocular lenses (IOL) with differences in the tilt of IOL.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHOD

Sixty-four eyes that had uncomplicated phacoemulsification and IOL implantation were assigned to 1 of 2 groups: Acryfold 60BB (HOYA [n=30 eyes]) and AcrySof MA60AC (Alcon [n=34 eyes]). All patients had best corrected visual acuity better than 20/25. High-order aberrations were measured using the Hartmann-Shack aberrometer at 4.0 mm and 6.0 mm wavefront aperture diameters, and the IOL tilt and decentration were measured using Scheimpflug videophotography.

RESULTS

There was a significant difference in the IOL tilt (60BB=2.22 degrees +/- 1.44 (SD), 60AC=3.18 +/- 1.84 degrees; P=.041, Mann-Whitney U test), but no difference in IOL decentration (P>.05). In the cornea, there were no differences between the 2 groups in HoAs at 4.0 mm and 6.0 mm aperture diameters (P>.05, Mann-Whitney U test). In the whole eye, there was no difference between the 2 groups in spherical-like aberrations, coma-like aberrations, and total aberrations at the 4.0 mm and 6.0 mm aperture diameters (P>.05). The compensation of the internal optics with the 60BB group was better than with the 60AC group for coma-like (P=.037) and total aberrations (P=.010) at 6.0 mm aperture diameter.

CONCLUSION

The smaller tilt of the IOL induced more compensation for the coma-like and total aberrations at the 6.0 mm aperture diameter. The IOL tilt should be small, especially in a large pupil, with regard to HoAs.

Influence of intraocular lens optical design on high-order aberrations

PURPOSE

To compare differences in high-order aberrations (HOAs) between 2 intraocular lens (IOL) optical designs.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHOD

Sixty eyes that had uncomplicated phacoemulsification and IOL implantation were assigned to 1 of 2 groups based on the type of IOL optical design: more posteriorly curved biconvex shape (AcrySof MA30BA, Alcon) (n=30 eyes) or more anteriorly curved biconvex shape (AcrySof MA30AC) (n=30 eyes). All patients had best corrected visual acuity better than 20/25. High-order aberrations were measured using a Hartmann-Shack aberrometer at 4.0 mm and 6.0 mm wavefront aperture diameters.

RESULTS

At 4.0 mm aperture diameters, there were no differences between the 2 groups in HOAs (P>.05, Mann-Whitney U test) in the cornea and the whole eye. At 6.0 mm aperture diameters, MA30AC eyes had a smaller amount of spherical-like aberrations (P=.043) than MA30BA eyes; however, there were no significant differences between the 2 groups in coma-like aberrations and total aberrations in the whole eye (P>.05). At 6.0 mm aperture diameters, there were no differences between the 2 groups HOAs in the cornea. (P>.05).

CONCLUSION

The optical design of the spherical IOL influenced the spherical-like aberrations in the whole eye. This may reduce retinal image quality.

Wavefront's role in corneal refractive surgery

In the 5 years since the first wavefront-based LASIK treatment on normal eyes, the ophthalmology profession has had to confront a new language based on astronomy, optics and mathematics. Over this time wavefront technology has been used for diagnosis and treatment, and its application has made the profession define what is meant by good vision, and determine whether, with psychophysical and psychometric tests, it is possible understand how an individual perceives the world. The clinical application of wavefront technology has forced ophthalmologists and vision scientists with an engineering bias to talk to those with a biological bias, and to appreciate that if you try and change the corneal shape, its biological, anatomical and optical properties exist within a complex external eye environment. This perspective article demonstrates that wave-front analysis is a useful diagnostic tool, and that wavefront-based corneal refractive surgery is an improvement over conventional techniques. Its use by an ophthalmologist is a clinical decision specific to an individual patient.