chromatic aberration of hydrophilic and hydrophobic iols

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  • ARTICLEQ 2015 ASC

    Published byIn vivo subjective and objectivelongitudinal chromatic aberrationafter bilateral implantation of the samedesign of hydrophobic and

    hydrophilic intraocular lensesMaria Vinas, MSc, Carlos Dorronsoro, PhD, Nuria Garzon, OD, MSc,

    Francisco Poyales, MD, Susana Marcos, PhDRS an

    ElsevPURPOSE: To measure the longitudinal chromatic aberration in vivo using psychophysical andwavefront-sensing methods in patients with bilateral implantation of monofocal intraocularlenses (IOLs) of similar aspheric design but different materials (hydrophobic Podeye andhydrophilic Poday).

    SETTING: Instituto de Optica, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.

    DESIGN: Prospective observational study.

    METHODS: Measurements were performed with the use of psychophysical (480 to 700 nm) andwavefront-sensing (480 to 950 nm) methods using a custom-developed adaptive optics system.Chromatic difference-of-focus curves were obtained from best-focus data at each wavelength,and the longitudinal chromatic aberration was obtained from the slope of linear regressions tothose curves.

    RESULTS: The longitudinal chromatic aberration from psychophysical measurements was 1.37diopters (D) G 0.08 (SD) (hydrophobic) and 1.21 G 0.08 D (hydrophilic). From wavefront-sensing, the longitudinal chromatic aberration was 0.88 G 0.07 D and 0.73 G 0.09 D,respectively. At 480 to 950 nm, the longitudinal chromatic aberration was 1.27 G 0.09 D(hydrophobic) and 1.02 G 0.13 D (hydrophilic). The longitudinal chromatic aberration wasconsistently higher in eyes with the hydrophobic IOL than in eyes with the hydrophilic IOL (adifference of 0.16 D and 0.15 D, respectively). Similar to findings in young phakic eyes, thelongitudinal chromatic aberration from the psychophysical method was consistently higherthan from wavefront-sensing, by 0.48 D (35.41%) for the hydrophobic IOL and 0.48 D(39.43%) for the hydrophilic IOL.

    CONCLUSION: Longitudinal chromatic aberrations were smaller with hydrophilic IOLs than with hy-drophobic IOLs of the same design.

    Financial Disclosure: No author has a financial or proprietary interest in any material or methodmentioned.

    J Cataract Refract Surg 2015; 41:21152124 Q 2015 ASCRS and ESCRSIn natural conditions with polychromatic light,retinal image quality is affected both by monochro-matic and chromatic aberrations of the ocular opticsand their interactions. Chromatic aberration in theeye arises from the wavelength dependence of thed ESCRS

    ier Inc.refractive index of the ocular media (chromaticdispersion) affecting diffraction, scattering, andaberrations.13 Chromatic dispersion causes shortwavelengths to focus in front of long wavelengths,producing a chromatic difference of focus betweenhttp://dx.doi.org/10.1016/j.jcrs.2015.11.009 21150886-3350

    http://crossmark.crossref.org/dialog/?doi=10.1016/j.jcrs.2015.11.009&domain=pdfhttp://dx.doi.org/10.1016/j.jcrs.2015.11.009

  • 2116 CHROMATIC ABERRATION WITH BILATERAL HYDROPHOBIC AND HYDROPHILIC IOLSthe shorter and longer wavelengths; this is known aslongitudinal chromatic aberration.4 The interactionsbetween chromatic and monochromatic aberrationshave drawn attention, particularly as the magnitudeand pattern of either aberration can be altered whenthe crystalline lens of the eye is replaced by an intraoc-ular lens (IOL). In phakic eyes, it has been shown thatmonochromatic aberrations play a protective roleagainst chromatic aberrations.5,6 This opens the dis-cussion of whether correction of both chromatic andmonochromatic aberrations are needed to improve vi-sual performance.7

    In phakic eyes, longitudinal chromatic aberrationhas been widely studied, and it is fairly acceptedthat it is rather constant across the population andwith age.8,9 However, the reported longitudinalchromatic aberration varies across studies, which isprobably associated with differences in the measure-ment techniques, psychophysical4,914 and reflecto-metric,1519 as well as the spectral range beingtested. In a recent study,20 we presented longitudinalchromatic aberration measured in the same subjectsusing psychophysical and reflectometry techniquesin a wide spectral range (450 to 950 nm) with adap-tive optics control of the subjects' natural aberra-tions. The longitudinal chromatic aberrationmeasured psychophysically was significantly higherthan that from reflectometry techniques (1.51 diopters[D] versus 1.00 D in the 480 to 700 nm range).

    In recent years, monofocal IOL designs haveimproved not only to restore transparency or to cor-rect refractive errors (sphere and cylinder) but alsoto reduce the spherical aberration of the eye.2125

    However, the replacement of the lens also modifiesthe chromatic dispersion properties of the eye, asSubmitted: January 16, 2015.Final revision submitted: March 30, 2015.Accepted: March 31, 2015.

    From the Instituto de Optica (Vinas, Dorronsoro, Marcos), ConsejoSuperior de Investigaciones Cientficas, and the Instituto deOftalmologa Avanzada (Garzon, Poyales), Madrid, Spain.

    Supported by PhysIOL, Liege, Belgium, European Research Coun-cil-2011-AdC 294099 (Dr. Marcos), Spanish Government grantFIS2011-25637 (Dr. Marcos), Consejo Superior de InvestigacionesCientficas Junta de Ampliacion de Estudios-Preprograms, andMinisterio de Ciencia e Innovacion Formacion de Profesotado Uni-versitario predoctoral fellowship (Dr. Vinas).

    Daniel Pascual and Daniel Cortes provided technical support.

    Corresponding author: Maria Vinas, MSc, Instituto de Optica s,Consejo Superior de Investigaciones Cientficas, Serrano 121,28006, Madrid, Spain. E-mail: maria.vinas@io.cfmac.csic.es.

    J CATARACT REFRACT SURG -this is affected by the refractive index wavelength de-pendency of the IOL material. Therefore, the opticalperformance of the pseudophakic in polychromaticlight will be determined by both the IOL design andthe IOL material.

    The impact of the chromatic aberrations in the pseu-dophakic eye has been acknowledged.2628 There areeven proposals for IOL (diffractive) designs aimed atcorrecting the ocular longitudinal chromatic aberra-tion.29,30 The dispersion properties of the IOL aredefined by the Abbe number (ranging in most designsfrom 35 to 60). The higher the Abbe number, the lowerthe longitudinal chromatic aberration. Most reports oflongitudinal chromatic aberration and polychromaticoptical quality in pseudophakic eyes are based oncomputational predictions on eye models and the IOLmaterial Abbe number.26,30,31 Few studies reportin vivomeasurements of longitudinal chromatic aberra-tion in pseudophakic eyes. Nagata et al.27 measured thelongitudinal chromatic aberration in vivo (500 to 650nm) in pseudophakic eyes with poly(methyl methacry-late) and acrylic IOLs, using a modified chromoretino-scopy system.32 Perez-Merino et al.33 reportedmonochromatic aberrationsmeasured at 2 wavelengths(532 nm and 785 nm) in 2 groups of pseudophakic eyeswith IOLs (Tecnis, Abbott Medical Optics, Inc., andAcrysof IQ, Alcon Laboratories, Inc.) of different mate-rials and found statistical differences between thechromatic difference of focus with the 2 IOL types(0.46 D and 0.75 D, respectively), consistent with theAbbe number of the IOLmaterials. Siedlecki et al.34 pre-sented the chromatic difference of focus in pseudo-phakic eyes with 2 types of Acrysof IOLs (IQSN60WF, spherical asymmetric biconvex IOL;SA60AT, aspheric asymmetric biconvex IOL; AlconLaboratories, Inc.) measured at 470 nm, 525 nm, and660 nm with the use of an autorefractometer adaptedto monochromatic measurements of refraction.

    In this study, we measured in vivo the longitudi-nal chromatic aberration in pseudophakic patientswho had bilateral implantation of monofocalaspheric hydrophobic and hydrophilic IOLs. Mea-surements were performed on patients using psy-chophysical and wavefront-sensing methods on acustom-developed adaptive optics platform providedwith a super-continuum laser source, a psychophysi-cal channel, a Hartmann-Shack wavefront sensor,and an electromagnetic deformable mirror to allowcontrol of monochromatic natural aberrations. Thepsychophysical longitudinal chromatic aberrationwas obtained in the visible range (480 to 700 nm),and the longitudinal chromatic aberration fromwavefront-sensing was obtained both in the visible(480 to 700 nm) and near infrared (IR) (700 to 900nm) ranges. Chromatic differences in focus curvesVOL 41, OCTOBER 2015

    mailto:maria.vinas@io.cfmac.csic.es

  • 2117CHROMATIC ABERRATION WITH BILATERAL HYDROPHOBIC AND HYDROPHILIC IOLSwere obtained from best focus data at each wave-length in each experiment, and the longitudinalchromatic aberration was obtained from the slopeof linear regressions to those curves. The measuredlongitudinal chromatic aberration was comparedbetween eyes of the same patient, with longitudinalchromatic aberration values obtained in youngphakic patients performed using the same experi-mental system and with longitudinal chromatic aber-ration reported in pseudophakic patients in theliterature.

    PATIENTS AND METHODS

    The longitudinal chromatic aberration was obtained frompsychophysical and wavefront-sensing measurements ofbest focus at 8 wavelengths in 9 patients who had bilateralimplantation of an IOL of the same design but different ma-terial (hydrophobic Podeye and hydrophilic Poday, bothPhysIOL). One eye of each patient was randomly assignedthe hydrophobic IOL and the contralateral eye, the hydro-philic IOL. The time between the surgeries on the eyes of apatient was fewer than 7 days.

    All participants were acquainted with the nature andpossible consequences of the study and provided writteninformed consent. All protocols met the tenets of theDeclaration of Helsinki and were approved by the SpanishNational Research Council (Consejo Superior de Investiga-ciones Cientficas) Bioethical Committee. All