Optical performance of multifocal intraocular lenses

Imaging Function and Relative Light Transmission of Explanted Opacified Hydrophilic Acrylic Intraocular Lenses

We evaluated the influence of intraocular lens (IOL) opacification on the optical performance of explanted hydrophilic acrylic IOLs. We performed a laboratory analysis of 32 Lentis LS-502-1 (Oculentis GmbH, Berlin, Germany) IOLs, explanted due to opacification, in comparison with six clear unused samples of the same IOL model. Using an optical bench setup, we obtained modulation transfer function (MTF), Strehl ratio, two-dimensional MTF, and United States Air Force (USAF) chart images. In addition, we assessed light transmission through the IOLs. The MTF values of opacified IOLs at 3-mm aperture were similar to those of clear lenses, with the median (interquartile range) values of 0.74 (0.01) vs. 0.76 (0.03) at the spatial frequency of 50 line pairs per millimeter in clear and opacified IOLs, respectively. The Strehl ratio of opacified lenses was not lower than that of clear lenses. The USAF-chart analysis showed a considerable reduction in brightness in opacified IOLs. The median (interquartile range) relative light transmission of opacified IOLs in comparison to clear lenses was 55.6% (20.8%) at the aperture size of 3 mm. In conclusion, the explanted opacified IOLs had comparable MTF values to those of clear lenses but significantly reduced light transmission.

Comparison of visual performance between two aspheric monofocal intraocular lens models

CLINICAL RELEVANCE

It is important to distinguish between visual acuity, optical quality and quality of vision when outcomes obtained with intraocular lenses are evaluated. These parameters, that includeobjective and subjective tests, should be assessed to obtain results that are not biased.

BACKGROUND

To assess the difference in visual and optical quality between two monofocal intraocular lens models.

METHODS

: This was a prospective, parallel and randomised clinical study conducted at Miranza IOA, a private clinic in Madrid, Spain. Sixty patients were implanted bilaterally, 30 per group, with two aspheric IOLs with induced spherical aberration of -0.27 μm for Group A and -0.20 μm for Group B. Visual outcomes obtained at 1 and 3 months after surgery included both uncorrected (UCVA) and corrected monocular distance visual acuity (DCVA), objective scattering index (OSI), modulation transfer function (MTF) cut-off, Strehl Ratio (SR), contrast sensitivity defocus curve (CSDC), intraocular lens spherical aberration (SA), and longitudinal chromatic aberration of the eye. Activity limitations in daily life were assessed using CatQuest-9SF questionnaire.

RESULTS

There were statistically significant differences for DCVA (0.04 LogMAR; p = .008) and SR (0.03; p = .003) between groups. Outcomes related to CSDC showed statistically significant differences for vergences between -0.50 D and +1.00 D (3 mm pupil) and for vergences of 0.00 D and +0.50 D (4.5 mm pupil) between groups. Overall, Group A showed better results regarding visual and optical quality, including a lower longitudinal chromatic aberration result in comparison to Group B. Patient satisfaction evaluated with CatQuest-9SF showed that Group A achieved better outcomes, although the differences were statistically significant only for the 'Reading text on television' item (p = 0.027).

CONCLUSIONS

Both intraocular lens models showed excellent quantity of vision, optical and visual quality as well as high patient satisfaction. Despite this, the the Group A model provided slightly better outcomes than the Group B model.

Citation network analysis of the various types of multifocal intraocular lenses

BACKGROUND AND OBJECTIVE

The implantation of multifocal intraocular lens (IOL) has increased in recent years, allowing patients to achieve good quality vision at all distances, independence from use of glasses, and consequently, an increase in quality of life. The main purpose of this study was to analyse the links between publications and authors via citation networks, as well to as identify the different research areas and determine the most cited publications.

MATERIAL AND METHODS

The publication search was performed through the Web of Science database, using the terms «Multifocal intraocular lens», «Bifocal intraocular lens», «Trifocal intraocular lens», «Diffractive intraocular lens», «Refractive intraocular lens», «Accommodative intraocular lens» and «Extended depth of focus intraocular lens», for a time interval from 1989 to August 2020. The software used to analyse the publications was the Citation Network Explorer.

RESULTS

A total of 1293 publications were found, with 11,730 citations generated in the network, and 2019 had the highest number of publications of any year. The most cited publication was «European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens» by Kohnen et al., published in 2006. Four groups about different research areas in this field were found using the Clustering functionality: visual quality, IOL designs, ocular aberrations, or defocus curves.

CONCLUSIONS

The citation network offers an objective and comprehensive analysis of the main articles on the different designs and classes of multifocal IOL.

Citation network analysis of the various types of multifocal intraocular lenses

BACKGROUND AND OBJECTIVE

The implantation of multifocal intraocular lens (IOL) has increased in recent years, allowing patients to achieve good quality vision at all distances, independence from use of glasses, and consequently, an increase in quality of life. The main purpose of this study was to analyse the links between publications and authors via citation networks, as well to as identify the different research areas and determine the most cited publications.

MATERIAL AND METHODS

The publication search was performed through the Web of Science database, using the terms «Multifocal intraocular lens», «Bifocal intraocular lens», «Trifocal intraocular lens», «Diffractive intraocular lens», «Refractive intraocular lens», «Accommodative intraocular lens» and «Extended depth of focus intraocular lens», for a time interval from 1989 to August 2020. The software used to analyse the publications was the Citation Network Explorer.

RESULTS

A total of 1293 publications were found, with 11730 citations generated in the network, and 2019 had the highest number of publications of any year. The most cited publication was «European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens» by Kohnen et al., published in 2006. Four groups about different research areas in this field were found using the Clustering functionality: visual quality, IOL designs, ocular aberrations, or defocus curves.

CONCLUSIONS

The citation network offers an objective and comprehensive analysis of the main articles on the different designs and classes of multifocal IOL.

Standard Results and Contrast Sensitivity Reestablishment after Implantation of a Trifocal Intraocular Lens

PURPOSE/AIM

To assess, following the standards, the results of safety, efficacy and predictability for a trifocal intraocular lens and to evaluate contrast sensitivity and visual acuity defocus curve.

MATERIALS AND METHODS

Fifty subjects operated on cataract surgery or refractive lens exchange with a trifocal intraocular lens have been recruited for the study. The monocular uncorrected visual acuity (VA) at far, intermediate (67 cm) and near (40 cm) distances in addition to corrected VA at far and near distances was evaluated at 1 week, 1 month and 3 months after surgery. Postoperative refraction, binocular contrast sensitivity function (CSF) and binocular defocus curves were also collected at the 3-month follow-up visit.

RESULTS

Mean uncorrected VA was 0.10, 0.07 and 0.05 logMAR at far, intermediate and near distances. Corrected distance VA at far and near distances was 0.04 and 0.02 logMAR. Ninety percent and 100% achieved a spherical equivalent in ±0.50 D and ±1.00 D, respectively. CSF was above normal range for 12 and 18 cycles per degree (cpd) in all the conditions, inside the normal range in 1.5, 3 and 6 cpd and only decreased below normal range for 1.5 and 3 cpd in mesopic vision without glare.

CONCLUSIONS

The procedure achieved a safety, efficacy and predictability similar to those reported by previous studies. The CSF was generally enhanced after the procedure in comparison to those reported in non-operated subjects above 60 years old. Previous studies might underestimate the effective distance of the intermediate and near foci.

Posterior Segment Visualization in Eyes With Small-Aperture Intraocular Lens

PURPOSE

To evaluate the posterior segment visualization in patients with small-aperture intraocular lens (IOL) implantation.

METHODS

In this prospective, comparative case series, 15 patients who had unilateral implantation of the small-aperture IOL in their non-dominant eyes were recruited. Their fellow eyes were pseudophakic with a monofocal IOL in 14 patients and phakic in 1 patient. All underwent bilateral posterior segment clinical investigations including fundus photography, threshold perimetry, and optical coherence tomography of the posterior pole including optic nerve head. The results from these investigations were graded by a clinician masked to the laterality and type of IOL. Patient 11 developed postoperative endophthalmitis 4 weeks following cataract surgery with implantation of a small-aperture IOL and underwent pars plana vitrectomy. The intraoperative view of the posterior segment was subjectively evaluated by the retinal surgeon.

RESULTS

All 15 patients had successful image captures with all clinical investigative tools with no differences in image quality detected between the images obtained from the monofocal pseudophakic and small-aperture IOL eyes. The small-aperture IOL did not subjectively obstruct the intraoperative view for the retinal surgeon during pars plana vitrectomy.

CONCLUSIONS

Standard posterior segment investigations including non-mydriatic fundus photography, optical coherence tomography, and automated perimetry can be safely and effectively performed in eyes with small-aperture IOLs. There is no difference in the image quality. [J Refract Surg. 2019;35(8):538-542.].

Fast Measure of Visual Acuity and Contrast Sensitivity Defocus Curves with an iPad Application

Objective:

To evaluate the repeatability of the fast measurement of the visual acuity (VADC) and contrast sensitivity (CSDC) defocus curves with a new test as well as the agreement of measurements at far distance obtained with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart and the ClinicCSF test for measuring Contrast Sensitivity Function (CSF).

Method:

Records from fifty-nine subjects implanted with Multifocal Intraocular Lenses (MIOLs) were retrieved from our database. VADC and CSDC were measured from +1.00 D to -4.00 D in 0.50 D steps. The agreement with the ETDRS and the CSF at far distance was assessed in comparison to the 0 D location of the VADC and the CSDC, respectively. The repeatability was evaluated in 34 subjects who consecutively repeated two measures.

Results:

Median Visual Acuity (VA) was -0.1 logMAR with the VADC at 0 D of defocus and 0 logMAR with the ETDRS (p>0.05). A total of 45.8% of eyes showed no differences between both tests and the difference was less than one line of VA in 96.6% of the eyes. The intrasubject repeatability was under one line of VA along all the defocus curve except for positive defocus levels. The CSDC showed the best agreement with the CSF for 18 cycles per degree. The CSDC was less repeatable than VADC. Mean time spent on completing the VADC and CSDC was 7.81 and 7.98 minutes, respectively.

Conclusion:

The VADC showed good agreement with the ETDRS and good repeatability despite the short testing time. In contrast, poorer repeatability was found for CSDC. Our method would facilitate the inclusion of VADC in clinical practice as it is a fast test, being also the first one including the measure of CSDC.

A Survey of Intraocular Lens Explantation: A Retrospective Analysis of 23 IOLs Explanted during 2005

Purpose

To evaluate the indications, lens styles, perioperative findings, and results of intraocular lens (IOL) explantation or exchange performed in the authors department in 2005.

Methods

The retrospective analysis comprised 22 patients (23 eyes). Twenty-one eyes had previous phacoemulsification and IOL implantation, one eye secondary aphakic IOL, and one eye phakic IOL implantation. The indications for IOL explantation/exchange and perioperative complications were evaluated. The best-corrected visual acuity (BCVA) before and after surgery was compared.

Results

Time from initial surgery to explantation/exchange varied from 1 to 121 months, median value was 46 months. The IOLs were explanted using local anesthesia and in 21 eyes replaced with new lens. Indications for IOL removal were opacification of the IOL in 12 eyes, malposition of the IOL in 5 eyes, postoperative refractive error in 2 eyes, recurrent toxic anterior segment syndrome in 1 eye, pseudophakic dysphotopsia in 1 eye, endothelial cell loss in phakic anterior chamber IOL in 1 eye, and visual discomfort with intraocular telescopic lens in 1 eye. The mean BCVA (decimal scale) before and after IOL explantation/exchange was 0.562±0.279 and 0.627±0.276, respectively. There was no significant difference in visual acuity before and after IOL exchange (Wilcoxon test).

Conclusions

The most frequent indications for IOL explantation/exchange were opacification of the IOL and IOL malposition. Surgeries were uneventful in most cases. Final visual results have been largely good. Long-term follow-up of patients with various types of IOLs should be maintained.

Patient-Perceived and Laboratory-Measured Halos Associated with Diffractive Bifocal and Trifocal Intraocular Lenses

PURPOSE

To examine and assess the halos generated in distance vision by multifocal intraocular lenses (IOLs) using both in vitro objective and in vivo subjective methods.

SETTING

The objective method was carried out in the optics laboratory of the Applied Optics and Image Processing Group (Universitat Politècnica de Catalunya -Barcelona). The psychophysical and subjective methods were carried out in the Instituto de Oftalmología Avanzada Madrid Innova Ocular.

DESIGN

Optical bench results and prospective evaluation of consecutive cases.

METHODS

The IOLs examined were TECNIS^®one-piece bifocals with addition powers of +4.00 D, +3.25 D, and +2.75 D and the trifocals AT-LISA-tri^® and FineVision^®. In the objective assessment, we examined halos around the far focus images of a pinhole formed by each IOL in an optical bench. For the in vivo study, we recruited 100 patients who had been bilaterally implanted one month earlier with the IOLs under study. Participants were subjected to psychophysical halometry (Halo v1.0) on the eye with better, distance-corrected, visual acuity and were required to subjectively grade halos by responding to the question "How much do halos bother you?"

RESULTS

The objective method revealed that the halo size increased with addition power and that the two trifocals gave rise to a double-halo pattern. Scores in the halometry also indicated a direct relationship between the halo size and addition power. The subjective results indicated fewer complaints about halos associated with the trifocal than bifocal IOLs.

CONCLUSIONS

The addition power of the tested IOLs affected both laboratory-measured and patient-perceived halos. Trifocal lenses generated fewer complaints about halos. Precise: Multifocal intraocular lenses (MIOLs) give rise to halos observed by patients under conditions of dim lighting. This study compares laboratory characterized halos generated by five MIOLs with patient-perceived halos.

Multifocal versus monofocal intraocular lenses after cataract extraction

BACKGROUND

Good unaided distance visual acuity (VA) is now a realistic expectation following cataract surgery and intraocular lens (IOL) implantation. Near vision, however, still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal) IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs.

OBJECTIVES

To assess the visual effects of multifocal IOLs in comparison with the current standard treatment of monofocal lens implantation.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to June 2016), Embase (January 1980 to June 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 13 June 2016.

SELECTION CRITERIA

All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included. We also considered trials comparing multifocal IOLs with "monovision" whereby one eye is corrected for distance vision and one eye corrected for near vision.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We assessed the 'certainty' of the evidence using GRADE.

MAIN RESULTS

We found 20 eligible trials that enrolled 2230 people with data available on 2061 people (3194 eyes). These trials were conducted in Europe (13), China (three), USA (one), Middle East (one), India (one) and one multicentre study in Europe and the USA. Most of these trials compared multifocal with monofocal lenses; two trials compared multifocal lenses with monovision. There was considerable variety in the make and model of lenses implanted. Overall we considered the trials at risk of performance and detection bias because it was difficult to mask participants and outcome assessors. It was also difficult to assess the role of reporting bias.There was moderate-certainty evidence that the distance acuity achieved with multifocal lenses was not different to that achieved with monofocal lenses (unaided VA worse than 6/6: pooled RR 0.96, 95% confidence interval (CI) 0.89 to 1.03; eyes = 682; studies = 8). People receiving multifocal lenses may achieve better near vision (RR for unaided near VA worse than J3/J4 was 0.20, 95% CI 0.07 to 0.58; eyes = 782; studies = 8). We judged this to be low-certainty evidence because of risk of bias in the included studies and high heterogeneity (I² = 93%) although all included studies favoured multifocal lenses with respect to this outcome.People receiving multifocal lenses may be less spectacle dependent (RR 0.63, 95% CI 0.55 to 0.73; eyes = 1000; studies = 10). We judged this to be low-certainty evidence because of risk of bias and evidence of publication bias (skewed funnel plot). There was also high heterogeneity (I² = 67%) but all studies favoured multifocal lenses. We did not additionally downgrade for this.Adverse subjective visual phenomena were more prevalent and more troublesome in participants with a multifocal IOL compared with monofocals (RR for glare 1.41, 95% CI 1.03 to 1.93; eyes = 544; studies = 7, low-certainty evidence and RR for haloes 3.58, 95% CI 1.99 to 6.46; eyes = 662; studies = 7; moderate-certainty evidence).Two studies compared multifocal lenses with monovision. There was no evidence for any important differences in distance VA between the groups (mean difference (MD) 0.02 logMAR, 95% CI -0.02 to 0.06; eyes = 186; studies = 1), unaided intermediate VA (MD 0.07 logMAR, 95% CI 0.04 to 0.10; eyes = 181; studies = 1) and unaided near VA (MD -0.04, 95% CI -0.08 to 0.00; eyes = 186; studies = 1) compared with people receiving monovision. People receiving multifocal lenses were less likely to be spectacle dependent (RR 0.40, 95% CI 0.30 to 0.53; eyes = 262; studies = 2) but more likely to report problems with glare (RR 1.41, 95% CI 1.14 to 1.73; eyes = 187; studies = 1) compared with people receiving monovision. In one study, the investigators noted that more people in the multifocal group underwent IOL exchange in the first year after surgery (6 participants with multifocal vs 0 participants with monovision).

AUTHORS' CONCLUSIONS

Multifocal IOLs are effective at improving near vision relative to monofocal IOLs although there is uncertainty as to the size of the effect. Whether that improvement outweighs the adverse effects of multifocal IOLs, such as glare and haloes, will vary between people. Motivation to achieve spectacle independence is likely to be the deciding factor.

Pseudolentogenic astigmatic effect of multifocal intraocular lenses: non-corneal ocular residual astigmatism (N-CORA) as a new parameter in astigmatic change analysis

PURPOSE

This study was initiated to introduce the term non-corneal ocular residual astigmatism (N-CORA) as a new parameter in astigmatic change analysis after implantation of two different types of non-toric, multifocal intraocular lenses (MIOL).

METHODS

Seventy-two eyes from 72 consecutive patients after MIOL surgery were studied in terms of a retrospective, cross-sectional data analysis. Two types of spherical MIOL were used. Surgical technique in all patients was a 2.4-mm incision phacoemulsification, performed by one surgeon. To investigate the magnitude and axis of astigmatic changes, the true corneal astigmatism and Alpins vector method were applied.

RESULTS

There were no statistically significant between-group differences related to the preoperative refraction or ocular residual astigmatism (ORA). After surgery, the mean refractive surgically induced astigmatism (RSIA) and the topographic SIA (TSIA) did not differ significantly between the lenses. The magnitude and orientation of ORA and N-CORA changed after surgery.

CONCLUSIONS

There are no statistically significant differences in postoperative ORA in magnitude or axis when implanting different types of MIOL. The similarity of N-CORA between both MIOL types shows that both diffractive and refractive asymmetric MIOLs with plate haptics have the same pseudolentogenic astigmatic effect which could be presented in terms of the newly introduced parameter N-CORA.

Ocular residual astigmatism (ORA) in pre-cataract eyes prior to and after refractive lens exchange

The purpose of this study was to analyze ocular residual astigmatism (ORA) before and after implantation of two different optical types of non-toric multifocal intraocular lenses (MIOL) in pre-cataract patients. This retrospective cohort study analyzed 72 eyes from 72 consecutive patients after MIOL surgery . To investigate magnitude and axis of astigmatic changes, the concepts of true corneal astigmatism and Alpins vector method were applied. There were no statistically significant between-group differences prior to surgery. The mean refractive surgically induced astigmatism (RSIA) (P = 0.063) and the topographic SIA (TSIA) (P = 0.828) did not differ significantly between the lenses, and the summated vector mean for ORA was reduced in terms of magnitude by approximately 0.30 Diopter. ORA in pseudophakic eyes mainly results from the posterior corneal surface and less from IOL tilting, postoperative posterior capsule shrinkage, or secondary cataract.

Modelling the effects of secondary spherical aberration on refractive error, image quality and depth of focus

PURPOSE

To examine the role of Zernike secondary spherical aberration and its component terms on refraction, image quality and depth of focus.

METHODS

Computational methods were used to define wavefronts with controlled levels of r(6) , r(4) and r(2) terms, and image quality associated with these terms for a range of target vergences. Target vergences that generated maximum image quality were used as an objective measures of refractive error.

RESULTS

Unlike primary Zernike spherical aberration, which generates peak image quality with a near paraxial focus, in the absence of other higher order aberrations, peak image quality with secondary spherical aberration is achieved with a near marginal focus. When alone, positive primary and secondary spherical aberration induce small hyperopic shifts in refraction, but in the presence of other higher order aberrations, secondary spherical aberration can induce significant myopic shifts in refractive error, as predicted by the combined lower order r(4) & r(2) component of Z60. The predicted expansion in depth of focus associated with increased primary or secondary spherical aberration is mostly absent if a strict image quality criterion is applied. The expansion of depth of focus observed with a low image quality criterion when opposite sign Z40 and Z60 are combined is primarily due to the elevated r(4) term.

CONCLUSIONS

Secondary Zernike spherical aberration can have a significant impact on refractive error, image quality and depth of focus, but mostly due to the lower order components within this polynomial. Our analysis shows that the r(6) term that defines secondary spherical aberration actually narrows rather than expands depth of focus, when in the presence of the r(4) term within Z60. Therefore, a multifocal lens generated with exclusively primary spherical aberration is likely to be more effective than one that includes opposite sign of primary and secondary spherical aberration.

Straylight Measurements in Two Different Apodized Diffractive Multifocal Intraocular Lenses

PURPOSE

To evaluate differences in straylight between eyes implanted with a hydrophilic multifocal IOL (Seelens MF; Hanita Lenses, Hanita, Israel) and a hydrophobic multifocal IOL (SN6AD1; Alcon Laboratories, Inc., Fort Worth, TX).

METHODS

In a prospective cohort study, routinely obtained straylight measurements (C-Quant; Oculus Optikgeräte, Wetzlar, Germany) 3 months after standard phacoemulsification for either cataract or refractive lens procedures were compared. Patients were implanted with either the SeeLens MF IOL or the SN6AD1 IOL. Postoperative straylight values, visual acuity, and refractive outcomes were compared.

RESULTS

The SeeLens MF IOL was implanted in 84 eyes and the SN6AD1 IOL in 79 eyes. The difference in straylight was 0.08 (P = .01), with the SeeLens MF IOL having less straylight. Postoperative CDVA was logMAR -0.03 ± 0.06 in the SeeLens MF group, and logMAR -0.02 ± 0.08 in the SN6AD1 group. Mean postoperative refraction was +0.01 ± 0.43 and +0.06 ± 0.35 D, respectively.

CONCLUSIONS

The Seelens MF IOL showed a stray-light of log(s) 0.08 lower than the SN6AD1 IOL. In terms of spherical equivalent and visual acuity the lenses performed equally. More study will aid in understanding the causes and clinical impact of this difference.

Long-term visual function and patient satisfaction after bilateral implantation and combination of two similar multifocal IOLs

PURPOSE

To evaluate the visual outcome, spectacle independence, and patient satisfaction after implantation of two Acrysof ReSTOR (Alcon Laboratories, Inc., Fort Worth, TX) intraocular lenses (IOLs) with different addition power or their combination in both eyes.

METHODS

One hundred twenty eyes of 60 patients with bilateral multifocal IOL implantation were divided into three groups of 20 consecutive patients each: the SV25T0 (the T0 group), the SN6AD1 (the D1 group), or a combination of both the SN6AD1 and SV25T0 (the combined group). Patients were observed 18 months postoperatively for visual acuity (40, 50, and 60 cm, and 4 m), defocus curves (range: +1.0 to -4.0 diopters), and contrast sensitivity. Quality of vision, patient satisfaction, and spectacle independence were evaluated by the National Eye Institute Refractive Error Quality of Life Instrument-42 questionnaire.

RESULTS

The D1 group achieved better results for near vision (P < .01), whereas the T0 group achieved better intermediate vision (P = .01). The combined group showed a wider range of spectacle independence at all distances evaluated (P < .05). The contrast sensitivity was similar within the groups. The incidence of glare was lower for the T0 group (P = .054). The combined group had better results in terms of expectation (P = .021) and activity limitation (P = .003).

CONCLUSION

Although the bilateral implantation of the same multifocal IOL can maximize the vision for near or intermediate distances, the combination of these IOLs in both eyes can increase the range of spectacle independence without compromising the contrast sensitivity and quality of vision.

Depth-of-field of the accommodating eye

Purpose

To obtain experimental values of the depth-of-field (DOFi) of the human eye for different accommodative states.

Methods

First, the monochromatic ocular wavefront of seven eyes from young subjects (mean [±SD] age, 29.7 [±7.7] years) was measured at eight different accommodative demands (ADs) (from −1 to 6 diopters [D] in steps of 1 D). Then, in a second part, accommodation was paralyzed and an adaptive optics system was used to correct the aberrations of the paralyzed eye and to simulate, with the aid of an artificial pupil, the wavefront of the accommodated eye. The simulation was performed for each AD measured in the first part of the experiment. A Badal system was used to modify the stimulus vergence so as to obtain three repeated measurements of the subjective DOFi, based on the criterion of an objectionable blur.

Results

When increasing AD from 0 to 6 D, the mean intersubject pupil diameter and DOFi changed from 5.70 to 4.62 mm and from 0.85 ± 0.26 D to 1.07 ± 0.19 D, respectively. All subjects presented a similar DOFi for all AD (intrasubject SD never exceeded 0.23 D). Paraxial accommodation response showed a lag that increased with the AD. For the lowest (0 D) and the highest (6 D) values of AD, the refractive state of the eye was close to the nearest and furthermost ends of the DOFi, respectively.

Conclusions

The visual system takes advantage of the DOFi to change the refractive state less than necessary to form the paraxial image at the retina when it comes to focusing a near target (5 to 6 D of AD). This indicates that the main purpose of accommodation is not to maximize retinal image quality but to form one that is good enough.

Evaluation of optical quality parameters and ocular aberrations in multifocal intraocular lens implanted eyes

PURPOSE

We investigated the correlations between optical quality parameters obtained from the double-pass system and ocular aberrations obtained from the ray-tracing aberrometer in multifocal intraocular lens (IOL) implanted eyes.

MATERIALS AND METHODS

Twenty eyes from 20 patients were enrolled in this study. Modulation transfer function cutoff frequency, The Strehl ratio, objective scatter index, and objective pseudo-accommodation obtained from the double-pass system were compared with root mean square (RMS) total aberration, RMS higher-order aberration, and spherical aberration obtained from the ray-tracing aberrometer. Additionally, parameters of the double-pass system and ray-tracing aberrometer were compared with manifested refraction values and subjective visual acuity, respectively.

RESULTS

There was no statistically significant correlation between optical quality parameters obtained from the double-pass system and ocular aberrations, except between the Strehl ratio and RMS total aberration (r=-0.566, p=0.018). No significant correlations were found between the parameters of both devices, and manifested refraction values or subjective visual acuity.

CONCLUSION

Optical quality parameters, especially the Strehl ratio, in multifocal IOL implanted eyes were affected by RMS total aberration. Further studies based on accurate measurements of ocular aberrations and additional optical quality parameters are needed to delineate relationships between optical quality parameters and ocular aberrations in multifocal IOL implanted eyes.

Impact of contact lens zone geometry and ocular optics on bifocal retinal image quality

PURPOSE

To examine the separate and combined influences of zone geometry, pupil size, diffraction, apodisation and spherical aberration on the optical performance of concentric zonal bifocals.

METHODS

Zonal bifocal pupil functions representing eye + ophthalmic correction were defined by interleaving wavefronts from separate optical zones of the bifocal. A two-zone design (a central circular inner zone surrounded by an annular outer-zone which is bounded by the pupil) and a five-zone design (a central small circular zone surrounded by four concentric annuli) were configured with programmable zone geometry, wavefront phase and pupil transmission characteristics. Using computational methods, we examined the effects of diffraction, Stiles Crawford apodisation, pupil size and spherical aberration on optical transfer functions for different target distances.

RESULTS

Apodisation alters the relative weighting of each zone, and thus the balance of near and distance optical quality. When spherical aberration is included, the effective distance correction, add power and image quality depend on zone-geometry and Stiles Crawford Effect apodisation. When the outer zone width is narrow, diffraction limits the available image contrast when focused, but as pupil dilates and outer zone width increases, aberrations will limit the best achievable image quality. With two-zone designs, balancing near and distance image quality is not achieved with equal area inner and outer zones. With significant levels of spherical aberration, multi-zone designs effectively become multifocals.

CONCLUSION

Wave optics and pupil varying ocular optics significantly affect the imaging capabilities of different optical zones of concentric bifocals. With two-zone bifocal designs, diffraction, pupil apodisation spherical aberration, and zone size influence both the effective add power and the pupil size required to balance near and distance image quality. Five-zone bifocal designs achieve a high degree of pupil size independence, and thus will provide more consistent performance as pupil size varies with light level and convergence amplitude.

Multifocal versus monofocal intraocular lenses after cataract extraction

BACKGROUND

Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL) implantation. Near vision, however, still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal) IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs.

OBJECTIVES

The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses in people undergoing cataract surgery.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 2), MEDLINE (January 1946 to March 2012), EMBASE (January 1980 to March 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 March 2012. We searched the reference lists of relevant articles and contacted investigators of included studies and manufacturers of multifocal IOLs for information about additional published and unpublished studies.

SELECTION CRITERIA

All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included.

DATA COLLECTION AND ANALYSIS

Two authors collected data and assessed trial quality. Where possible, we pooled data from the individual studies using a random-effects model, otherwise we tabulated data.

MAIN RESULTS

Sixteen completed trials (1608 participants) and two ongoing trials were identified. All included trials compared multifocal and monofocal lenses but there was considerable variety in the make and model of lenses implanted. Overall we considered the trials at risk of performance and detection bias because it was difficult to mask patients and outcome assessors. It was also difficult to assess the role of reporting bias. There was moderate quality evidence that similar distance acuity is achieved with both types of lenses (pooled risk ratio (RR) for unaided visual acuity worse than 6/6: 0.98, 95% confidence interval (CI) 0.91 to 1.05). There was also evidence that people with multifocal lenses had better near vision but methodological and statistical heterogeneity meant that we did not calculate a pooled estimate for effect on near vision. Total freedom from use of glasses was achieved more frequently with multifocal than monofocal IOLs. Adverse subjective visual phenomena, particularly haloes, or rings around lights, were more prevalent and more troublesome in participants with the multifocal IOL and there was evidence of reduced contrast sensitivity with the multifocal lenses.

AUTHORS' CONCLUSIONS

Multifocal IOLs are effective at improving near vision relative to monofocal IOLs. Whether that improvement outweighs the adverse effects of multifocal IOLs will vary between patients. Motivation to achieve spectacle independence is likely to be the deciding factor.

[Vision with bifocal and multifocal intraocular lenses]

Bifocal or multifocal intraocular lenses (IOLs) can be used to replace natural lenses during cataract surgery. These lenses are recommended by cataract surgeons as the replacement lenses of choice when patients wish to avoid wearing spectacles. There are, however, drawbacks to these lenses: one drawback is that the contrast in the images of bifocal and multifocal lenses is reduced as documented in the ophthalmology literature. It is claimed that acuity is similar in multifocal compared to monofocal lenses, however, we show that any loss in contrast inevitably reduces visual acuity. The other drawback is that the sharp in-focus image is always seen superimposed on one or more blurred out of focus images of the same object. In the ophthalmology literature it is assumed that the brain can suppress the undesired blurred image and only perceive the sharp image. We argue that there are no known mechanisms that would make this possible. This means that vision with bifocal or multifocal implanted lenses cannot be as good as vision with monofocal implants supplemented by spectacles, and this should be explained to patients before undergoing surgery for lens replacement. The results also hold for bifocal and multifocal contact lenses.

Postoperative astigmatic outcomes based on the haptic axis of intraocular lenses inserted in cataract surgery

Purpose

This study was conducted to compare post-operative astigmatic outcomes of two groups, with-the-rule (WTR) and against-the-rule (ATR) astigmatism patients, according to the haptic axis of intraocular lenses (IOLs) inserted in cataract surgery.

Methods

Seventy-two eyes with WTR astigmatism and 79 eyes with ATR astigmatism had cataract surgery through a clear corneal temporal incision. These two groups of eyes were then each divided into 2 groups based on whether the haptic axis of the inserted IOL was at 180° or 90°. For ATR patients, the outcomes were analyzed according to the three types of IOLs.

Results

There was no difference in corneal astigmatism, but WTR patients with a 180° haptic axis of the inserted IOL and ATR patients with a 90° hepatic axis of the inserted IOL had a significant decrease in postoperative refractive astigmatism (p < 0.05). The changes in ATR astigmatism according to the IOL type were more effective in single-piece acrylic IOLs than in the three-piece polymethylmethacrylate haptic IOL group.

Conclusions

Insertion of the IOL at the 180° haptic axis in WTR patients and at 90° in ATR patients during cataract surgery may have an effect in reducing pre-existing astigmatism. This observed effect was not consistent among the different types of IOLs.

Visual impact of Zernike and Seidel forms of monochromatic aberrations

PURPOSE

The aim of this study was to examine the impact of different aberrations modes (e.g., coma, astigmatism, spherical aberration [SA]) and different aberration basis functions (Zernike or Seidel) on visual acuity (VA).

METHODS

Computational optics was used to generate retinal images degraded by either the Zernike or Seidel forms of second through fourth-order aberrations for an eye with a 5-mm pupil diameter. High contrast, photopic VA was measured using method of constant stimuli for letters displayed on a computer-controlled, linearized, quasimonochromatic (lambda = 556 nm) display.

RESULTS

Minimum angle of resolution (MAR) varied linearly with the magnitude (root mean square error) of all modes of aberration. The impact of individual Zernike lower- and higher-order aberrations (HOAs) varied significantly with mode, e.g., arc minutes of MAR per micrometer of root mean square slopes varied from 7 (spherical defocus) to 0.5 (quadrafoil). Seidel forms of these aberrations always had a smaller visual impact. Notably, Seidel SA had 1/17th the impact of Zernike SA with the same wavefront variance, and about 1/4th the impact of Zernike SA with matching levels of r wavefront error. With lower-order components removed, HOAs near the center of the Zernike pyramid do not have a large visual impact.

CONCLUSIONS

The majority of the visual impact of high levels of fourth-order Zernike aberrations can be attributed to the second-order terms within these polynomials. Therefore, the impact of SA can be minimized by balancing it with a defocus term that flattens the central wavefront (paraxial focus) or maximizes the area of the pupil with a flat wavefront. Over this wide range of aberration types and levels, image quality metrics based on the Point Spread Function (PSF) and Optical Transfer Function (OTF) can predict VA as reliably as VA measures can predict retests of VA, and, thus, such metrics may become valuable predictors of both VA and, via optimization, refractions.

Evaluation of the aspheric tecnis multifocal intraocular lens: one-year results from the first cohort of the food and drug administration clinical trial

PURPOSE

To evaluate the safety and effectiveness of the aspheric diffractive Tecnis multifocal ZM900 (TCMF) intraocular lens (IOL; Abbott Medical Optics, Inc, Santa Ana, California, USA).

DESIGN

One-year, nonrandomized, multicenter, evaluator-masked, bilateral, parallel-group comparative clinical evaluation.

METHODS

Subjects underwent bilateral implantation with the TCMF IOL or the CeeOn 911A monofocal (CEMN) IOL (Abbott Medical Optics, Inc) according to subject preference.

RESULTS

One-year results were available for 244 eyes of 125 TCMF IOL subjects and for 245 eyes of 123 CEMN IOL subjects. Mean distance visual acuities (VAs) were statistically and clinically equivalent between the 2 groups. Mean binocular and monocular uncorrected and distance-corrected near VAs were significantly better for the TCMF IOL versus the CEMN IOL group (P < .0001). A greater proportion of TCMF IOL versus CEMN IOL subjects achieved binocular combined VAs of 20/25 distance and 20/32 near (84.2% [96/114] vs 6.2% [7/113]; P < .0001). The TCMF IOL group had excellent depth of focus, maintaining a mean of 20/40 or better for far, intermediate, and near distances. Mean contrast sensitivity scores were lower for the TCMF IOL versus the CEMN IOL group, but the differences were not considered clinically significant. Halos and night glare were more common in the TCMF IOL versus the CEMN IOL groups. Both reading acuity (20/20 vs 20/47; P < .0007) and speed (148 vs 117 words/minute; P < .0001) were significantly better for the TCMF IOL versus the CEMN IOL group, as were the proportions of the TCMF IOL group versus the CEMN IOL group that achieved spectacle independence (84.8% vs 5.2%; P < .0001) and that functioned comfortably at near without glasses (96.4% vs 30.4%; P < .0001).

CONCLUSIONS

The TCMF IOL provided enhanced near VA, reading acuity per speed, depth of focus, and spectacle independence compared with the monofocal IOL.

Assessing the optical performance of multifocal (diffractive) intraocular lenses

BACKGROUND AND PURPOSE

While the optical performance of monofocal refractive lenses can be measured quite easily, more efforts are required to assess the performance of multifocal lenses, due to imaging to several foci. The purpose of this study was to develop a rugged test setup for evaluation of the optical properties of intraocular lenses (IOLs) in conformity to the International Standard ISO 11979.

METHODS

We built a test setup in order to measure the point spread function and to determine the modulation transfer function (MTF) of IOLs. We measured three multifocal IOLs with (1) a diffraction limited model cornea and (2) an individualized aspheric model cornea which shows a significant amount of spherical aberration.

RESULTS

All the three IOL samples tested showed a different impact of spherical aberration on the MTF. The bispheric lenses (Alcon and Dr Schmidt) showed a degradation of the MTF and Strehl ratio with model (2) compared to model (1). In contrast, the MTF of the Tecnis lens, which has a prolate aspheric front surface, improved dramatically in combination with model (2).

CONCLUSION

We demonstrated the functional capability of our measurement system by presentation of a set of working examples. Two different model corneas were used to study the influence of spherical aberration on the MTF of our working examples. An aspheric model cornea, which had already been shown to be suitable for testing monofocal aspherics, was shown to be well suited for testing aspheric multifocal lenses.

Post-capsulotomy dysphotopsia in monofocal versus multifocal lenses

PURPOSE

To compare the photic symptoms experienced by patients with the monofocal SI30 intraocular lens (IOL) with the refractive multifocal SA40 Array IOL after capsulotomy.

METHODS

In this prospective cohort study, 49 eyes of 49 patients (20 multifocal, 29 monofocal IOLs) were assessed following uncomplicated cataract extraction and Nd:YAG capsulotomy equal to the scotopic pupillary diameter. Subjects with post-operative refraction of +/-1.00 or more DS, +/-1.00 or more DC, concurrent ocular pathology, LogMAR acuity of worse than 0.3 for distance or 1.0 for near were excluded. Glare and halo were assessed objectively with computer-generated psychophysical tests (Glare and Halo) and subjective dysphotopic symptoms were evaluated with Tester, Javitt, Winther-Neilsen and Sedgewick questionnaires.

RESULTS

No significant difference was found for mean halo size (square degrees) between monofocals (121.33) and multifocals (97.32, p = 0.207) or for mean glare (percentage contrast), monofocals (7.881) and multifocals (7.353, p = 0.812). No significant differences in the subjective appreciation of dysphotopsia were found: Tester (p = 0.358), Javitt (p = 0.29), Winther-Neilson (p = 0.54) and Sedgewick questionnaires (p = 0.134).

CONCLUSION

The posterior capsule is an important optical medium, which has not been fully considered in other comparative studies and its complete removal eliminates any confounding contribution. The results suggest that after capsulotomy, there is no significant difference in objective or subjective photic phenomena between monofocal and multifocal silicone lenses. Dysphotopic symptoms in patients with refractive multifocal IOLs were comparable to monofocal IOL patients after capsulotomy.

Visual function with bilateral implantation of monofocal and multifocal intraocular lenses: a prospective, randomized, controlled clinical trial

PURPOSE

To evaluate visual function of three types of multifocal intraocular lenses (IOLs) and one monofocal IOL (as the control group) after cataract surgery.

METHODS

One hundred fourteen patients participated in a prospective, randomized, controlled clinical study and received monofocal Tecnis Z9000 (AMO) (n = 24, 48 eyes); symmetric diffractive multifocal Tecnis ZM900 (AMO) (n = 26, 52 eyes); zonal refractive multifocal ReZoom (AMO) (n = 32, 64 eyes); and asymmetric diffractive multifocal TwinSet (Acri.Tec) (n = 32, 64 eyes) IOLs.

RESULTS

Mean binocular distance best spectacle-corrected visual acuity (BSCVA) (logMAR) was 0.05 for controls, 0.08 for ZM900, 0.07 for ReZoom, and 0.11 for TwinSet, with mean binocular distance BSCVA at near of 0.49, 0.06, 0.22, and 0.11, respectively. Mean contrast sensitivity was better for the monofocal IOL group than for the multifocal IOLs. Patients assigned to TwinSet had less favorable contrast sensitivity scores. Patients with monofocal IOLs had more frequently recommended near addition (74%) than those with multifocal IOLs. Patients with refractive ReZoom had also recommended near addition more frequently than the two diffractive groups. The percentage of dysphotopsia phenomena was 81% in patients with diffractive multifocal ZM900 compared with 48% in patients with monofocal IOLs, 53% with refractive ReZoom, and 47% with diffractive TwinSet.

CONCLUSIONS

The monofocal IOL showed better visual function and lesser photic phenomena than multifocal IOLs but patients were spectacle dependent. ReZoom provided better distance BSCVA than the TwinSet diffractive model. Patients with Tecnis and TwinSet diffractive multifocal IOLs were more spectacle independent than patients with ReZoom. Patients with TwinSet had the worst visual function. Patients implanted with the Tecnis diffractive ZM900 were those reporting more photic phenomena.

Multifocal intraocular lenses in the setting of glaucoma

PURPOSE OF REVIEW

The purpose of this review is to collate evidence and make recommendations regarding the use of multifocal intraocular lenses in patients with glaucoma.

RECENT FINDINGS

Multifocal intraocular implants have been in use since the 1980s. Several studies have been done comparing their advantages and disadvantages compared with conventional monofocal intraocular implants. Most of these studies have looked at patients with cataract and no ocular comorbities. Reports of their use in eyes with concurrent disease are scarce. We review the available evidence and the potential benefits and pitfalls of using multifocal intraocular lenses in glaucomatous eyes. A recently published Cochrane review identified eight trials which had stringent criteria to recruit patients. These studies excluded all patients with concurrent eye diseases. No recent publications are available specifically evaluating the use of multifocal intraocular lenses in patients with glaucoma.

SUMMARY

Firm recommendations cannot be made on the use of multifocal intraocular lenses in patients with glaucoma as large studies have not been done to evaluate their benefit. Currently, the decision of whether to use multifocal intraocular lenses in patients with glaucoma has to be made on an individual basis.

Multifocal versus monofocal intraocular lenses after cataract extraction

BACKGROUND

Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL) implantation. Near vision however still requires additional refractive power usually in the form of reading glasses. Multiple optic (multifocal) IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs.

OBJECTIVES

The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which includes the Eyes and Vision Group Trials Register) on The Cochrane Library (2006, Issue 3), MEDLINE (1966 to July 2006), EMBASE (1980 to July 2006), NRR (2006, Issue 3) and PUBMED searched on 25 July 2006, limit: 90 days (entry date). We searched the reference lists of relevant articles and contacted investigators of included studies and manufacturers of multifocal intraocular lenses for information about additional published and unpublished studies.

SELECTION CRITERIA

All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included.

DATA COLLECTION AND ANALYSIS

Data were collected and trial quality was assessed. Where possible, statistical summary measures were calculated otherwise data were tabulated.

MAIN RESULTS

Ten trials were identified, and a further three are pending review. There was significant variability between the trials in which outcomes were reported. Unaided distance acuity was similar in multifocal and monofocal IOLs (standardised mean difference (SMD) 0.03, 95% Confidence Interval (CI) -0.13 to 0.19). There was no statistical difference between multifocal IOLs and monofocals with respect to the proportion of participants achieving 6/6 best corrected visual acuity (Peto odds ratio (OR) 1.05, 95% CI 0.67 to 1.63). Unaided near vision was improved with the multifocal IOLs. Total freedom from use of glasses was achieved more frequently with multifocal than monofocal IOLs (OR for spectacle dependence 0.17, 95% CI 0.12 to 0.24). Adverse effects included reduced contrast sensitivity and the subjective experience of haloes around lights.

AUTHORS' CONCLUSIONS

Multifocal IOLs are effective at improving near vision relative to monofocal IOLs. Whether that improvement outweighs the adverse effects of multifocal IOLs will vary between patients. Motivation to achieve spectacle independence is likely to be the deciding factor.

Optical surface optimization for the correction of presbyopia

Presbyopia, the gradual loss of accommodation that accompanies aging, can be corrected by creating asphericity in the optical path of the eye. Bifocal and aspheric contact lenses, intraocular lenses, spectacle lenses, and laser refractive surgery are all widely used to alleviate the symptoms of presbyopia. These types of corrective surfaces try to concentrate vision in limited peaks over the full range of vergences. The methodology described in this paper is designed to correct presbyopia by optimizing vision over the entire target range of near to distant. A corrective surface was created by employing an iterative function minimization algorithm to optimize an optical metric. In most cases, it is possible to obtain an optical surface that will optically compensate for presbyopia.

Visual performance of AcrySof ReSTOR apodized diffractive IOL: a prospective comparative trial

PURPOSE

Evaluate the visual performance of the AcrySof ReSTOR intraocular lens (IOL) and compare it with the monofocal SA60AT IOL.

DESIGN

Prospective, nonrandomized, clinical trial.

METHODS

Forty patients (80 eyes) from the Federal University of São Paulo were enrolled in two groups. Twenty-five patients were assigned to the ReSTOR group and 15 patients to the monofocal group. Inclusion criteria were corneal astigmatism <1.0 diopter, potential acuity meter >0.2 logMAR units, and no associated ocular diseases. Parameters analyzed included distance uncorrected and best-corrected visual acuity, near uncorrected and distance corrected visual acuity, intermediate visual acuity, contrast sensitivity (Pelli-Robson chart), stereopsis (Titmus test), reading speed, wavefront measurement (LADARWave aberrometer), and a quality-of-life questionnaire. main outcome measure: Distance and near uncorrected and best distance corrected visual acuity, contrast sensitivity, and reading speed.

RESULTS

Distance uncorrected and best-corrected visual acuity in the ReSTOR group were not statistically different from the monofocal group (P = .66). Near uncorrected and distance corrected visual acuity were statistically better in the ReSTOR group than the monofocal group (0.16 +/- 0.13 vs 0.62 +/- 0.09, P < .001, and 0.14 +/- 0.12 vs 0.62 +/- 0.07, P < .001, respectively). The ReSTOR group demonstrated less spherical aberrations compared with the monofocal group (P < .001). Monocular photopic contrast sensitivity was statistically lower in the ReSTOR group (P < .001). Stereopsis and reading speed were not statistically different between the groups.

CONCLUSION

The AcrySof ReSTOR IOL provides a satisfactory full range of vision and achieves a more satisfactory quality of life when compared with the monofocal SA60AT IOL, but with lower contrast sensitivity.

Correction of Presbyopia by Technovision Central Multifocal LASIK (PresbyLASIK)

PURPOSE

To investigate central multifocal presbyLASIK based on the creation of a central hyperpositive area.

METHODS

Twenty-five patients (50 eyes) underwent presbyLASlK in an open-label, prospective, non-comparative pilot study. Mean patient age was 58 years (range: 51 to 68 years), mean preoperative spherical equivalent refraction was +1.6 +/- 0.63 diopters (D) (range: +0.50 to +3.00 D), and mean spectacle near addition was +2.27 +/- 0.37 D (range: +1.75 to +3.00 D). The ablation pattern was performed with proprietary software from Technovision using an H. Eye Tech. excimer laser platform.

RESULTS

Mean postoperative spherical equivalent refraction was -0.37 +/- 0.55 D (range: -1.50 to + 1.00 D) and mean spectacle near addition was +1.72 +/- 0.34 D (range: +1.25 to +2.25 D). After 6 months, 16 (64%) patients achieved a distance uncorrected visual acuity (UCVA) of > or = 20/20 and 18 (72%) patients achieved a near UCVA of > or = 20/40. Seven (28%) patients lost a maximum of 2 lines of best spectacle-corrected visual acuity (BSCVA). The safety index for distance was 0.98 binocular and for near was 0.99 binocular. After 6 months, no significant change was noted in contrast sensitivity at 1.5 cycles/degree. A significant mean reduction was found at spatial frequencies of 3, 6, 12, and 18 cycles/degree (P<.001). There was a significant change in corneal aberrations after surgery. The coefficients for coma increased and the coefficients for spherical aberrations decreased. A significant decrease was noted in point spread function values (P=.0018).

CONCLUSIONS

Central presbyLASIK may be used to provide improvement in functional near vision in patients with presbyopia associated with low and moderate hyperopia. However, factors involved in the loss of BSCVA in some cases and loss in vision quality should be further clarified prior to its general use.

European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens

OBJECTIVE

To report the safety and effectiveness of the AcrySof ReSTOR apodized diffractive intraocular lens (IOL), model MA60D3, when implanted into the capsular bag.

DESIGN

Multicenter European study including university clinics, eye hospitals, and private ophthalmic surgical centers.

PARTICIPANTS

One hundred twenty-seven subjects implanted in cataractous eyes in an open multicenter study.

INTERVENTION

After phacoemulsification, the foldable 3-piece hydrophobic acrylic apodized diffractive IOL was implanted in the capsular bag using a Monarch injector with an A-cartridge. The mean preoperative patient age was 68.4+/-12 years. Intraocular lens implant power ranged from 18.0 to 25.0 diopters (D) in 0.5-D increments.

MAIN OUTCOME MEASURES

Distance visual acuity (VA), near VA, spectacle dependence, unwanted visual symptoms, and patient satisfaction.

RESULTS

At the 6-month postoperative visit, binocular (both eyes simultaneously) mean uncorrected distance and near logarithm of the minimum angle of resolution VAs for the MA60D3 were 0.04+/-0.14 and 0.09+/-0.12 (n = 118), respectively. In addition, 88.0% and 84.6% of ReSTOR subjects achieved spectacle independence for distance and near vision, respectively. Glare and halos were reported as severe by only 8.5% and 4.2% of patients, respectively. Ninety-two percent of patients stated that they would choose to have the same lens implanted again after the first implant, and 95.7% answered likewise after the second implant.

CONCLUSIONS

The AcrySof ReSTOR MA60D3 IOL demonstrated excellent near VA without compromising distance vision. Spectacle independence and patient satisfaction were high, whereas unwanted photic phenomena were clinically acceptable.

Multifocal intraocular lenses

PURPOSE OF REVIEW

Multifocal intraocular lenses (IOLs) are growing in popularity among patients and surgeons, and opened the way to refractive lens exchange. Still they are not used routinely in cataract surgery, for reasons probably connected to the frequently observed reduction in contrast sensitivity. Recent papers with clinical study outcomes can help in understanding the advantages and the limits of multifocal IOLs.

RECENT FINDINGS

Emerging from every published study, both refractive and diffractive multifocal IOLs usually provide good near visual acuity with distance correction. As many multifocal IOLs are distance-dominant, near vision can be improved by correcting for near the distance focus. The near contrast sensitivity thus obtained is similar to that of monofocal IOLs. Multifocal IOLs have been employed with success in complicated cataract surgery and in trauma cases, with the same outcome as in normal cataract cases. Presbyopic lens exchange remains controversial, with a high success rate in original ametropic eyes, but limited success in original emmetropic eyes. Secondary procedures to improve the refractive outcome are usually of little efficacy in improving patient satisfaction. A new anterior chamber phakic multifocal IOL has been designed to correct presbyopia and small refractive errors. The first clinical results indicate high patient satisfaction, with 7.3% explantation rate.

SUMMARY

Multifocal IOLs can be more widely used after cataract surgery, but should be used with caution in almost emmetropic eyes with little or no cataract. Refractive lens exchange with multifocal IOL is especially worthwhile in hyperopic eyes. The new phakic multifocal IOL adds the concept of reversibility to presbyopic lens exchange.

Comparison of Wavefront Aberrations and Optical Quality of Eyes Implanted With Five Different Intraocular Lenses

PURPOSE

We compared corneal and total higher order wavefront aberrations in 25 pseudophakic eyes implanted with five different types of intraocular lenses to obtain an objective evaluation of the optical quality of these pseudophakic eyes. Five IOLs per type were studied.

METHODS

Implanted lenses were the Pharmacia Tecnis Z9000 with negative spherical aberration, Pharmacia 911 Edge, Alcon Acrysof SA60AT and MA60BM, and Allergan Sensar AR40e. Eyes were examined using the Topcon KR-9000PW topographer/aberrometer, which obtains simultaneous coaxial measurements of corneal and ocular aberrations, and displays the calculated Point Spread Function (PSF) and Modulation Transfer Function (MTF).

RESULTS

Corneal spherical aberration was positive in all tested eyes. For a 4-mm optical zone, ocular spherical aberration was 0.0054+/-0.0172 microm root-mean-square (RMS) in eyes implanted with the Tecnis lens, and was 0.0562 to 0.0974 microm RMS in eyes implanted with the four other conventional IOLs. A myopic refractive shift with mydriasis of -0.08 D occurred with the Tecnis IOL; it was -0.57 to -0.90 D with the conventional IOLs. Coma did not show a substantial reduction with any of the IOLs. Total wavefront aberrations showed nonsignificant reduction with the Tecnis lens. The PSF and the MTF also showed nonsignificant improvements over conventional IOLs.

CONCLUSIONS

The optical quality of pseudophakic eyes can be measured in vivo by aberrometers. Different IOLs resulted in measurably different outcomes. In this preliminary study, compensation of the spherical aberration observed with the Tecnis lens confirmed the theoretical predictions associated with this lens and resulted in no myopic shift in refraction with mydriasis.