www.eyeworld.org

The News Magazine of the American Society of Cataract and Refractive Surgery

“ As a surgeon I define success through mypatients’ satisfaction. With newer, advancedtechnologies targeting decreased higher order aberrations, we now have the opportunity toprovide even better outcomes for a widerrange of cataract and refractive patients.”

Eric D. Donnenfeld, M.D.

Innovations in Corneal andCataract Refractive Surgery

CONTRIBUTORS

David J. Tanzer, M.D.Jack T. Holladay, M.D.Louis E. Probst, M.D.Stephen C. Coleman, M.D.Perry S. Binder, M.D.Steven C. Schallhorn, M.D.Eric D. Donnenfeld, M.D.Edward J. Holland, M.D.Robert J. Weinstock, M.D.Randall J. Olson, M.D.David R. Hardten, M.D.George Beiko, BM, BCh, FRCS(C) Y. Ralph Chu, M.D. Douglas D. Koch, M.D.Li Wang, M.D.

Supported by a grant from AMO, Inc.

A S C R S C H I C A G O 2 0 0 8 E Y E W O R L D S U P P L E M E N T

RefractiveCataract SurgeryPages 10–15

The Ocular SurfacePages 8–9

Laser VisionCorrectionPages 2–7

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Patient Visual Quality and Acuity OutcomesRedefined with Fully Customized Procedures

2 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

Results from our recentstudy of naval aviationpatients show that wave-front-guid-ed/femtosecond LASIK

represents the best refractive pro-cedure performed today. Patientsexperience rapid visual recoveryby two weeks post-op. The refrac-tive results are stable in the major-ity of patients at one week. Inaddition, patients have improvedquality of vision, and they haveno complications or subjectivecomplaints. One hundred percentof patients strongly recommendthe procedure for fellow aviators.

Navy studyFor our Phase I Return to

Flight Study, 30 Class II aviators(USN / USMC) were enrolled andtreated (six female, 24 male).These aviators (51 myopic/myopicastigmatism eyes, four hyperopiceyes, and five mixed astigmatismeyes) received wavefront-guidedLASIK with 60 kHz IntraLase andthe Visx S4 IR (Advanced MedicalOptics); there were no nomogramadjustments. The surgical regimenincluded Pred Forte (prednisoloneacetate, Allergan, Irvine, Calif.)and Vigamox (moxifloxacin HCIophthalmic solution, Alcon, FortWorth, Texas) qid for one weekand Restasis (cyclosporine oph-thalmic emulsion, Allergan,Irvine, Calif.) bid for threemonths. There were weekly examsfor four weeks, then monthlythrough three month post-op.Aviators were eligible to return toflight by one month. Treatmentwas completed December 2007.

For uncorrected visual acuity,at one week a little over 90% were20/20 uncorrected. At two weeks,100% were 20/20 uncorrected and94% were 20/15 uncorrected. Inaddition, at two weeks, over halfthe patients were 20/12 uncorrect-ed and 25% were 20/10 (Figure 1).At four weeks, 87% were 20/12following wavefront-guidedLASIK. For best spectacle correctedvisual acuity, there was significantimprovement at four weeks, with93% of eyes at 20/12 or betterwith wavefront-guided LASIK(Figure 2). A significant numberof eyes gained BSCVA vision; 43%gained one line and 18% gainedtwo lines of best corrected vision.No eye lost more than two lines ofBSCVA. The study also showedthat LASIK patients have a greaterpercentage of eyes with better lowcontrast visual acuity than PRK.

Return to flightThere are clear advantages of

performing wavefront-guidedLASIK, including faster return tovisual function, and in the aviatorpatient population this means afaster return to duty. It appearsbased on our study data thatmyopes (who comprised well over90% of our population) are stableat two weeks following wavefront-guided femtosecond LASIK.

More studies are underwayincluding those in the designatedaviator population (pilots), as wellas studies in the accessioning pop-ulation, which will allow studentaviators who have had successfulLASIK to enter flight training.

Navy preferredWavefront-guided ablations

with femtosecond flap creationrepresents the preferred refractiveprocedure performed in the U.S.Navy today.

The excellent data and find-ings of this study will likely resultin waverability approval of WFGLASIK for naval aviation.

David J. Tanzer, M.D., is the U.S.Navy Refractive Surgery ProgramDirector, and Director of RefractiveSurgery at the Navy RefractiveSurgery Center, Naval MedicalCenter, San Diego, Calif.

Wavefront-guided and femtosecond laser combination speeds return to flightStudies with naval aviators show excellent post-op vision and stabilityby David J. Tanzer, M.D.

“ Wavefront-guided ablationswith femtosecondflap creation represents the pre-ferred refractiveprocedure performed in theU.S. Navy today.”

David J. Tanzer, M.D.

Figure 1: Uncorrected visual acuity: 100% of eyes treated with wavefront-guided ablations andfemtosecond flap creation were 20/20 or better by two weeks, compared to 80% with wave-front-guided PRK

Figure 2: In a comparative study between wavefront-guided ablations with femtosecond flapcreation LASIK and wavefront-guided PRK, BSCVA with LASIK is much improved over wave-front-guided PRK

Laser Vision Correction — Show Supplement • ASCRS Chicago 2008 3

Arecent study demonstratesthat the wavefront-guidedLASIK procedure inducessignificantly less higherorder aberrations, spheri-

cal aberration, trefoil, and comathan the wavefront-optimizedLASIK procedure. In some cases,wavefront-optimized LASIKinduced aberrations. Thus, wave-front-guided ablations provide thebest results for the vast majority ofpatients with the lowest rate ofretreatment over conventionalLASIK and wavefront-optimizedLASIK.

Reducing aberrations Studies show that less higher

order aberrations in the eye resultin better quality of vision. In thelaboratory, Pablo Artal, Ph.D.,showed eliminating all higherorder aberrations produces thebest visual performance. In addi-tion, studies from SteveSchallhorn, M.D., with 140 pilotsand 228 clinic patients showedthat the best visual performanceoccurred with the lowest amountof higher order aberrations.Similarly, pilots who had neverhad surgery naturally had lowerhigher order aberrations.

With wavefront-optimizedLASIK, the goal is not to reducethe spherical aberration, but sim-ply not increase it. The treatmentbasis is sphere and cylinder.Optimized simply means “notintended to induce spherical aber-ration,” and therefore does notaddress pre-op spherical aberrationor any other higher order aberra-tions. Numerous studies haveshown that by the time mostpatients reach their 40s, they havepositive ocular spherical aberra-tions. With wavefront-guidedLASIK, the goal is to reduce allhigher order aberrations. Thespherical aberration target is zero.

Study and resultsThe purpose of our study is to

compare wavefront-optimized andwavefront-guided procedures todetermine which is more effective.The retrospective chart reviewstudy of 200 IntraLASIK proce-dures included 100+ IntraLase(Advanced Medical Optics, AMO,Santa Ana, Calif.) Wavelight(wavefront-optimized) eyes and100+ IntraLase CustomVue (AMO)(wavefront-guided) eyes. Pre-opand post-op wavefront scans weredone on all eyes at a 6-mm pupilsize. Primary spherical aberrations,primary coma, primary trefoil, and

total higher order aberrations weremeasured.

One hundred and nineCustomVue eyes and 102Wavelight eyes were reviewed in2006 and early 2007. These studyresults show that wavefront-guid-ed ablation with femtosecondtechnology is optimal for themajority of patients.

Overall, the wavefront-guidedtreatment induces significantlyless higher order aberrations,spherical aberration, trefoil, andcoma than the wavefront-opti-mized procedure (Figure 1 and 2).There was significantly more varia-tion with the wavefront-optimizedeyes. This study indicates that forall higher order aberration in thewavefront-guided group, about12% of patients were better, 76%were the same, and 12% were

worse post-op. With wavefront-optimized, about 8% were better,51% were the same, and 41% wereworse. There was significantlygreater safety for the patients withthe guided procedure. The wave-front-guided procedure had thegreater efficacy for total higherorder aberrations, and the bettersafety with the lowest inducedaberrations.

We have found that wave-front-guided LASIK has the bestchance of maintaining or improv-ing higher order aberrations, andtherefore has the best chance ofproviding optimal visual quality.

Jack T. Holladay, M.D., is clinicalprofessor of ophthalmology at BaylorCollege of Medicine, in Houston,Texas. Contact him at holla-day@docholladay.com.

Fewer high order aberrations yields better visual performanceThe goal of customized LASIK is to reduce all higher order aberrations

by Jack T. Holladay, M.D.

“ We have foundthat wavefront-guided LASIK hasthe best chance ofmaintaining orimproving higherorder aberrations,and therefore hasthe best chance ofproviding optimalvisual quality.”

Jack T. Holladay, M.D.

Figure 1: Wavefront-guided ablations were shown to improve or have no change on higherorder aberrations (HOA) in 88% of all patients in the study

Figure 2: Wavefront-optimized ablations worsened higher order aberrations (HOA) in 41% ofall patients treated in the study, compared to 12% with wavefront-guided ablations

4 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

LASIK retreatment rates havebeen steadily declining. Inmy own practice, the rate ofenhancements has declinedfrom about 5% to 6% in

2004 to less than 2% in 2007.New technology has been themajor driver in this trend.

I recently analyzed retreat-ment rates for more than 15,000procedures over a three-year peri-od, from August 2004 to August2007. All the procedures were per-formed by me at TLC centers inChicago, Illinois, Madison,Wisconsin, and Greenville, SouthCarolina.

The resulting graph (Figure 1)shows how the different technolo-gies have influenced the rate ofretreatments. One caveat inunderstanding this graph is thatduring the period tracked, thenumber of custom procedures Iperformed was increasing and thenumber of conventional proce-dures was declining (Figure 2).

By the end of 2005, very fewof my patients opted for a conven-tional ablation. Most of those whodid were people for whom a cus-tom procedure was not possiblefor some reason. They may havehad unusually high prescriptionsor perhaps were difficult to cap-ture with the WaveScan(Advanced Medical Optics, AMO,Santa Ana, Calif.) and thereforeprobably skewed toward a higherretreatment rate anyway.

Today, I no longer performconventional procedures at all. Ifthe cornea is not thick enough forthe planned custom ablation, Iprefer to decrease the ablationdepth by adjusting the ablationzone rather than move to a con-ventional procedure. With thisapproach, the patient still benefitsfrom higher-order aberration cor-rection, iris registration, and othercustom technology.

At the same time that conven-tional procedures were declining,the number of microkeratomeprocedures was also rapidly declin-ing. In fact, beginning in Januaryof 2007 when TLC changed itspricing model to bundle IntraLase(AMO) flaps with custom ablation,virtually everyone who got onetechnology upgrade got themboth (this is represented on thegraph by the Custom IntraLaseline). By default, every conven-tional case also had a microker-atome flap.

Custom and femtosecondtechnologies seem to have a sym-biotic effect in reducing theenhancement rate. By mid-2007, I

had personally stopped using amicrokeratome at all, and theAdvanced CustomVue (AMO) andIntraLase group has the lowestenhancement rate on the graph.Conversely, the number ofpatients who receive conventionaland microkeratome procedures isso small that the enhancementrate for those lines looks dispro-portionately high.

The combination of AdvancedCustomVue and IntraLase takes usthat much closer to the ultimategoal that every patient sees 20/20

or better uncorrected the day aftersurgery. The best part about reduc-ing enhancements is not sometheoretical cost savings for thepractice; it is that we end up withmore happy patients who reachtheir visual goals the first timearound. Those patients will begreat spokespeople for LASIK andfor our practices in the future.

Louis E. Probst, M.D., is the medicaldirector of TLC Laser Eye Centers.Contact him at 608-249-6000.

“ The combina-tion of AdvancedCustomVue andIntraLase takes usthat much closer tothe ultimate goalthat every patientsees 20/20 or better uncorrectedthe day after surgery.”

Louis E. Probst, M.D.

Boost patient satisfaction with lower enhancement ratesNew technologies reduced this surgeon’s enhancement rate to less than 2% by Louis E. Probst, M.D.

Figure 1: Dr. Probst has seen a dramatic drop in his enhancement rate with the combination ofwavefront-guided ablations and femtosecond flap creation

Figure 2: Because of his experiences with the technology, Dr. Probst now primarily performs custom treatments with femtosecond flap creation

Laser Vision Correction — Show Supplement • ASCRS Chicago 2008 5

The current generationWaveScan (AdvancedMedical Optics, AMO,Santa Ana, Calif.), which isalready very good, captures

an average of 240 data points froma 7.0-mm pupil and analyzes allavailable data using Fourier recon-struction. AMO’s new high-defini-tion technology, however, willoffer five times greater resolution,encompassing over 1,250 datapoints from a 7.0-mm pupil. Evenwith a much smaller pupil of only5.0 mm, the system will captureover 600 data points.

The device, called the iDesignAdvanced WaveScan Studio, willalso have a broader dynamicrange, able to image wavefrontsfrom –16 D to +12 D of sphere,up to 8 D of cylinder, and up to 8microns of RMS higher-order aber-ration. By comparison, the currentsystem measures up to 1.3 micronsof RMS error. This advanced sys-tem will incorporate five measure-ments in one: wavefront aberrom-etry, new-technology topography,autorefractometry, pupillometry,and keratometry.

In addition to obtaining moreinformation, the higher resolutionaberrometer will provide muchbetter spot quality, resulting in afar more accurate representation ofthe true wavefront (Figure 1).

The benefits of enhanced orhigh-definition wavefront aber-rometry will be seen first in treat-ment planning for therapeuticcases. We’ll be able to look ataccurate representations of thewavefront from eyes with severeaberrations from previous RK,corneal scars, or laser surgery withdecentered ablations or otherproblems.

Ultimately I expect those ben-efits to translate into greater accu-racy in our primary procedures aswell. Once the high-resolutionimaging is linked to the laser, it ispossible that we will even begin toroutinely see reductions in higher-order aberration (HOA).

Topography’s roleIn recent years, wavefront

technology has advanced so rapid-ly that we have largely movedaway from strictly topography-based applications like C-CAP orA-CAP for highly aberrated eyes.

We knew the ability to influ-ence the wavefront with topo-graphical information would bevery powerful, but the challengein doing this has always been thattopography and wavefront datacome from two separate

sources. In order for both to influ-ence the laser ablation, they must,almost by definition, be generatedby the same device to ensure accu-rate registration.

The new topography technolo-gy that will soon be integratedinto the aberrometer is a high-speed, full-gradient system thatdoes not in any way use thePlacido ring method we are famil-iar with in standard topographyunits (Figure 2).

I would expect this technologyto first be available in therapeuticcases, much as C-CAP was. Buteventually, I think we’ll see topog-raphy data incorporated into pri-mary procedures in normal eyes.

As a first step, for example, we willbe able to import true topographicdata from many spots on thecornea to more fully compensatefor the cosine effect.

In the future, state-of-the-artlaser refractive surgery will involvecentralized diagnostic planning ina single device, and topography-assisted, wavefront-guided abla-tion with iris registration.

Stephen C. Coleman, M.D., is in pri-vate practice at Coleman VisionCenter in Albuquerque, N.M. Contacthim at 505-821-8880 orStephen@colemanvision.com.“ In addition to

obtaining moreinformation, thehigher resolutionaberrometer willprovide much better spot quality,resulting in a farmore accurate rep-resentation of thetrue wavefront.”

Stephen C. Coleman, M.D.

High-definition wavefront: 5X resolution Therapeutic treatments will be the first application, but high-definition scans and new-technology topography may eventually be incorporated into routine cases

by Stephen C. Coleman, M.D.

Figure 1: The high-definition aberrometer has a higher dynamic range and provides a more accurate representation of the wavefront, especially for unusual eyes

Figure 2: The new full gradient topography technology uses the Hartmann-Shack to collect information

6 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

Femtosecond technologynow provides surgeonswith the ability to biome-chanically design theLASIK flap by controlling

its shape (diameter, hinge size,side cut architecture, elliptical orround) and thickness, while alsoincreasing safety and speed.

The technology has evolvedtremendously since its commercialintroduction in 2001. Now, a 5thgeneration femtosecond laser (iFSAdvanced Femtosec-ond laser,Advanced Medical Optics, AMO,Santa Ana, Calif.) allows the flap tobe created in less than 10 seconds.

Speed The increased speed allows sur-

geons to use less energy per spotand to place the spots and linescloser together. Less pulse energyhas the potential to decrease theincidence of the opaque bubblelayer (OBL). In addition, faster flapcreation means less suction timeon the eye which contributes topatient comfort.

Arturo Chayet, M.D., Tijuana,Mexico, conducted the first twoclinical studies using the iFS laser.The first series determined the opti-mal settings for the laser while thesecond series looked at the clinicaladvantages of customizing flapdimensions for a given patient.

With the iFS laser, the spot lineseparation can be decreased fromthe current 8 to 9 microns spotand line separation to as low as 5 x5 microns (although the softwarepermits even tighter placement).Thus flap lifts are virtually effort-less and the beds potentiallysmoother than even those with thecurrent IntraLase FS system.

Mechanical stabilityThe iFS uses new software that

allows surgeons to customize theshape of the flap based on thepatient’s corneal diameter, shape,and the excimer laser ablationprofile. The surgeon may choosethe elliptical flap option whichcreates a larger stromal bed area.While maintaining the verticaldiameter, the horizontal diameteris enlarged, pushing the hingeaway from the ablation zone. Thisprevents the risk of hinge ablationor allows the creation of a widerhinge, enhancing flap stability(Figure 1).

Perhaps the most interestingand unique feature of the new iFSlaser is the ability to create aninverted “bevel-in” side cut. Thenew iFS laser side cut can be pro-grammed from 30 to 150 degrees

(similar to a mechancical micro-keratome).

The purpose for making a morevertical flap edge was initiallybased on a pig eye study thatmeasured how much force it tookto dislocate a flap. When the wallsare more perpendicular it is moredifficult to move that flap. Studiesconducted independently andmost recently by Prof. JohnMarshall and Prof. Dr. MichaelKnorz prove that the 140 to 150degree bevel-in side cut is an essen-tial component to a biomechani-cally stable cornea (Figure 2). Prof.Knorz’ comparative study conclud-ed that flaps created with the iFSlaser, utilizing a 140-degree sidecut, required three times as muchforce to dislodge than those creat-ed with a modern microkeratome.

Side cut architecture with theiFS femtosecond laser may alsodecrease the incidence of epithe-lial in-growth, which is common

after enhancing a microkeratomeflap, but it’s much less commonafter enhancing a femtosecondflap.

Femtosecond lasers havemany clinical applications. Inaddition to flap-making capabili-ties, surgeons also have the abilityto create channels for the implan-tation of intracorneal ring seg-ments, wedge resections, cornealtattooing, limbal stem cell trans-plantation, lamellar and full thick-ness corneal transplants, retinalkeratoplasty, corneal biopsies,and IntraLase EnabledKeratoplasty (IEK) patterns. Thisstate-of-the-art technology trulyrepresents a significant advance inthe field of refractive surgery.

Perry S. Binder, M.D., is in practicein San Diego, Calif., and is co-med-ical director for AMO/IntraLaseCorporation. Contact him at gar-rett23@aol.com.

“ Femtosecondtechnology nowprovides surgeonswith the ability tobiomechanicallydesign the LASIKflap by controllingits shape andthickness whilealso increasingsafety.”

Perry S. Binder, M.D.

The Femtosecond differenceWith the latest femtosecond laser technology, surgeons can make customizable, stable, and safer flaps more quickly than ever

by Perry S. Binder, M.D.

Figure 1: An elliptical flap enlarges the stromal bed area, moving the hinge away from the ablation zone

Figure 2: Studies have shown that side cut angles have a large impact on the stability of thecornea; bevel-in angles produce the least strain change on the cornea; the iFS has the abilityto customize the side cut angle from 30 to 150 degrees

Laser Vision Correction — Show Supplement • ASCRS Chicago 2008 7

Studies conducted at theNaval Medical Center inSan Diego have demon-strated that we canachieve significantly bet-

ter uncorrected visual acuity withfemtosecond laser flaps (300 eyes)(IntraLase 15 Khz, AdvancedMedical Optics, AMO, Santa Ana,Calif.) than with microkeratomeflaps (436 eyes) (Hansatome,Bausch & Lomb, Rochester, N.Y.,and Amadeus, AMO) three monthspost-op.

One week post-op, 76% offemtosecond eyes were 20/16 orbetter, compared to 58% of themicrokeratome eyes, and twice asmany femtosecond eyes were20/12.5 or better (Figure 1). Bythree months, there were stillmore femtosecond patients withbetter than 20/20 vision, but themicrokeratome group was catchingup.

The femtosecond eyes also hadbetter low-contrast acuity underboth photopic and mesopic condi-tions.

The advantages of the fem-tosecond laser may be due to flaparchitecture. When a mechanicallycreated flap is repositioned on theeye it may be difficult to surgicallydiscern the perfect position, whilethe side cut of the femtosecondflap makes correct repositioningmore obvious.

We only followed thesepatients for three months. It ispossible that both groups wouldhave attained the same levels ofvisual acuity and low-contrast acu-ity by six or 12 months post-op,but if the main advantage ofLASIK is rapid visual recovery,sooner is better.

The femtosecond flap group inour study did experience morephotophobia and foreign bodysensation on the first post-op day,a phenomenon that seems to havedisappeared with the faster itera-tions of the laser.

Future improvementsFuture generations of fem-

tosecond technology such as theiFS Advanced Femtosecond Laser(AMO), will offer a number ofadvantages over the currentIntraLase system:

Speed. We have already movedfrom 15 to 60 Khz and future fem-tosecond lasers will be faster still.In addition to faster throughputwith flap creation in under 10 sec-onds, there are a number of clini-cal advantages, including asmoother bed, a flap that is easier

to lift, and increased patient com-fort.

Flap stability. An angled bevelin the femtosecond laser side cutmight improve the strength of theLASIK flap, according to tworecent studies. Michael Knorz,M.D., compared flaps created withthe Amadeus microkeratome andthe IntraLase laser, with either a70- or 140-degree side cut angle.Three months later, the 140-degree IntraLase flaps were morethan three times as strong as themicrokeratome flap (Figure 2).Arturo Chayet, M.D., showedthat beveled-angle flaps are muchmore difficult to re-lift 10 weekslater, again indicating that we maybe able to increase flap stabilitywith modifications to the side-cutarchitecture.

Customization. With the nextgeneration iFS, we will be able tocustomize the shape of the flapitself, to make a more ellipticalflap. Instead of the one-size-fits-allapproach, we are entering an erawhen the flap will be tailored tothe individual eye.

I believe transitioning to laserflap creation is worth the costsassociated with new technology.There is tremendous potential tocontinue improving and morefully customize surgery with thefemtosecond laser.

Steven C. Schallhorn, M.D., is in pri-vate practice in San Diego, Calif. Hewas formerly the director of refractivesurgery at the Naval Medical Centerin San Diego, Calif. Contact him atscschallhorn@yahoo.com.

“ I believe transitioning tolaser flap creationis worth the costsassociated withnew technology.There is tremen-dous potential tocontinue improvingand more fully customize surgerywith the femtosec-ond laser.”

Steven C. Schallhorn, M.D.

Faster visual recovery with femtosecondIn the near future, state-of-the-art laser vision correction will incorporate an evenfaster femtosecond laser with greater customization and better side-cut architecture

by Steven C. Schallhorn, M.D.

Figure 1: At one week post-op, significantly more patients who had femtosecond-created flapshad UCVA of 20/16 or better

Figure 2: In a study by Michael Knorz, M.D., flap tensile strength was three times strongerwith a 140-degree side-cut femtosecond flap compared to a mechanical microkeratome flap

8 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

Dry eye syndrome is partic-ularly prevalent in post-menopausal women, peo-ple over 65, and youngerpeople who have become

contact lens-intolerant. The first defense against dry

eye will almost always be artificialtears. I am certainly an advocateof topical cyclosporine therapyand mild steroid treatment asneeded, but I think it is importantto start with a high-quality tearthat can provide symptomaticrelief on its own or as an adjunctto prescription therapies.

One new entrant in the mar-ket is blink Tears (AdvancedMedical Optics, AMO, Santa Ana,Calif.). In addition to the activeingredient, polyethylene glycol400 (PEG-400), this tear also hasunique properties that make itquite similar to the natural mucinfound in human tears.

Our group recently conducteda randomized, double-masked,parallel-group study in which 110dry-eye patients, ranging in agefrom 19 to 78, were given eitherblink Tears or Systane (Alcon, FortWorth, Texas), an HP guar-basedartificial tear. Patients wereinstructed to use the drops fourtimes a day for 30 days and wereexamined on days 7, 14, 21, and30.

There was significantly lessblur (P =.046) and better comforton instillation (P = .017) withblink Tears compared to Systane.End-of-day vision quality wascomparable between the twogroups. Objective testing, includ-ing corneal/conjunc-tival stainingand tear film break-up time(TBUT) analysis, also showed thatthe two drops were comparable inefficacy.

Thirty-six percent of the blinkTears group preferred the newdrop to their previous artificialtear, while only 12% preferredSystane over the products theyhad previously used.

Both drops were similar interms of retention. My colleagueKerry Solomon, M.D., hasdemonstrated in optical tear filminterferometry studies that themean retention time for blinkTears is longer than 31 minutesand that more of these patientsare likely to achieve a retentiontime greater than 30 minutes thanthose using Systane (Figure 1).

Pilot study AMO also undertook an inter-

nal pilot study to evaluate subjec-tive comfort and vision qualitywith blink Tears. In this double-masked trial, 24 subjects were ran-domized to either blink Tears orSystane, with 12 in each group.

There were important differ-ences in visual quality. Subjects inthe blink Tears group had animprovement in quality of visionof 0.33 ± 2.2 points, compared toa decrease in quality of –2.05 ± 2.5in the Systane group. Moreover,subjects in the blink Tears groupreported significantly less blur oninstillation (Figure 2) and weremore than twice as likely (90% vs.42%) to say that the tear had noeffect on their quality of vision

immediately after instillation. This is quite striking. Blurring

on instillation is a tradeoff thatpatients don’t like.

Based on my own clinicalexperience thus far, I considerblink Tears to be a truly refractivetear. Not only does it smooth outand regularize the tear film, mak-ing it a better refracting surfaceover the long run, but it alsoappears to have no short-termnegative effect on the quality ofvision.

Eric D. Donnenfeld, M.D., is in pri-vate practice with OphthalmicConsultants of Long Island and is atrustee of Dartmouth Medical School.Contact him at 516-766-2519 oreddoph@aol.com.

Blink Tears offers less blur than SystaneRandomized, double-masked study shows that patients prefer blink Tears over previously used dry eye products

by Eric D. Donnenfeld, M.D.

“ Based on myown clinical experience thusfar, I consider blinkTears to be a trulyrefractive tear. Notonly does it smoothout and regularizethe tear film…butit also appears tohave no short-termnegative effect onthe quality ofvision, as otherlong-lasting dropstypically do.”

Eric D. Donnenfeld, M.D.Figure 1: In a comparative study, subjects who used Blink Tears were more likely to experi-ence a retention time of longer than 30 minutes than subjects using Systane. Data courtesy ofKerry Solomon, M.D.

Figure 2: Subjects in the Blink Tears group were more than twice as likely to say that the tearhad no effect on their quality of vision immediately after instillation than subjects in theSystane group

The Ocular Surface — Show Supplement • ASCRS Chicago 2008 9

Dry eye is such a commoncondition that in our prac-tice it has become thedefault diagnosis for exter-nal disease symptoms

until something in the exam indi-cates otherwise. One is most likelyto see dry eye in post-menopausalwomen, the elderly, post-surgicalpatients, and those suffering fromcontact lens intolerance.

For patients who experiencedry eye symptoms only under cer-tain environmental conditions,artificial tears alone may be suffi-cient. For most chronic dry eyepatients, however, I quickly moveto add topical cyclosporine(Restasis, Allergan, Irvine, Calif.) asmaintenance therapy and a courseof loteprednol (Lotemax, Bausch &Lomb, Rochester, N.Y.) for induc-tion therapy as well as for break-through inflammation.

Restasis has dramaticallychanged our ability to managethese patients, but it certainly doesnot eliminate the need for tearsfor symptomatic relief. The prob-lem with tears is that patients rap-idly become symptomatic againand then get frustrated with theinconvenience of having to fre-quently instill tears throughoutthe day. Gels last longer and makethe patient feel more comfortable,but those benefits have generallycome at the expense of reducedquality of vision.

Recently, we’ve seen a majorbreakthrough with a new tearproduct, blink Tears (AdvancedMedical Optics, AMO, Santa Ana,Calif.). The unique properties ofthis tear help it adhere to thecorneal surface so that it reducessymptoms for a longer duration.In fact, for its viscosity, blink Tearsis one of the longest-lasting tearproducts available. Optical tear-film interferometry studies haveshown that the mean retentiontime after just one instillation ofblink Tears is longer than 31 min-utes, and in some cases, the tearfilm maintains its thickness for anhour or longer.

But in addition to the longduration of effect, what really dis-tinguishes blink Tears are itssuperb optical qualities. Patientsexperience very little blurring orother problems with visual claritywhen using this tear. In fact, theyreport improved quality of visionover time (Figure 1) and signifi-cant improvement in comfort afterusing the drops for a few weeks(Figure 2).

Pre-op managementWe often delay elective ocular

surgery for one to two months inorder to have time to improve thehealth of the ocular surface.

For our refractive patients, ahealthy tear film is going to pro-duce better pre-op topographyand wavefront exams, a tighterrefraction, and speed up visualrecovery after surgery. Cataractpatients are even more likely tohave dry eye than our youngerrefractive surgery patients, so welike to treat their dry eye prior tosurgery as well.

Blink Tears is ideal for thesepatients as they prepare for sur-gery because they do not need touse it constantly or suffer fromreduced quality of vision. I expectthat blink Tears will become oneof my first line options for dry eyeand pre-surgical populations forthese reasons.

Edward J. Holland, M.D., is professorof ophthalmology at the University ofCincinnati and Director of CorneaServices at the Cincinnati EyeInstitute. Contact him at 513-984-5133 or eholland@fuse.net.

High quality tears essential in treatment of dry eyeDry eye is a pervasive condition in many of our patient populations; appropriate diagnosis and treatment can have a positive impact on patient satisfaction

by Edward J. Holland, M.D.

“ In addition tothe long durationof effect, whatreally distinguishesblink Tears are itssuperb opticalqualities.”

Edward J. Holland, M.D.

Figure 1: When asked within the first five minutes after instillation of blink Tears whether theirquality of vision was improved, patients increasingly responded that it had “definitelyimproved” over several weeks of using the tears

Figure 2: In clinical trials, patients reported significant improvement in end-of-day comfortafter 30 days of using blink Tears

10 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

Recently, I had an opportu-nity to try the latest pha-coemulsification modality,transversal ultrasound,using the Ellips

Transversal Ultrasound handpiecefor the WhiteStar Signature system(Advanced Medical Optics, AMO,Santa Ana, Calif.).

Ellips adds a horizontal com-ponent to the traditional longitu-dinal movement of the phaco nee-dle, creating an elliptical cuttingpattern (Figure 1). By incorporat-ing two directions of movement(lateral and longitudinal), wewould theoretically expect toachieve more efficient cutting ofnuclear material. Moreover, it alsohas the potential to reduce therepulsion of material away fromthe phaco tip, hopefully improv-ing followability of fragments andreducing the jackhammer effect.

During a field observationstudy, I performed 20 cases in myown surgery center, all withbimanual phaco and transversalultrasound.

There was no learning curve ofany significance for a surgeon whois familiar with the Sovereign(AMO) or WhiteStar Signature sys-tem. In order to best assess thepotential advantages of the newultrasound mode, I deliberatelymade no changes to my custom-ary technique, settings, or instru-mentation. I was able to use thesame irrigating chopper that I nor-mally use, and the same tip—a 19-gauge, straight 30-degree bevelphaco needle.

I chose routine cases for theinitial experience. I began eachcase with longitudinal phaco fornuclear sculpting. Once the nucle-us was cracked, I advanced to thetransversal setting for quadrantremoval at higher vacuum settings(Figure 2).

The purchase, followability,and efficiency of nuclear removalwas excellent. Very little phacopower was needed to remove thenuclear particles.

The transversal setting seemedto perform slightly better on softto moderate nuclei rather thanvery dense nuclei. However, it istoo soon for me to say with anyauthority how this technology canbest be used until I and othershave had an opportunity to adjustsettings and fully customize thesystem to my surgical techniqueand nuclear density.

What was most impressiveabout my initial experience wasthe post-op day one results. Thecorneas were beautifully clear—infact, noticeably clearer than I amaccustomed to with my currentphaco machines and settings. Thiswas quite surprising, as one wouldexpect to see more corneal edema,not less, after the first surgical daywith a new technology.

Based on the clarity of thecorneas post-op, I believe thattransversal ultrasound may be lesstraumatic for the eye, deliveringless energy with less irrigationfluid and less damage to theendothelium compared to conven-tional longitudinal phaco.

While clear corneas are cer-tainly gratifying for the surgeon tosee on the first day post-op, theyare also indicative of a great expe-rience for the patient. Thatpatient is going to have fastervisual recovery, increased comfort,and the ability to proceed withsurgery on the second eye in amore timely fashion. The moreatraumatic we can make cataractsurgery, the better the overallexperience for the patient, andthe more likely he or she is to rec-ommend us or refer friends.

Dr. Weinstock is in private practiceat the Eye Institute of West Florida,Largo. Contact him at 727-581-8706 or rjweinstock@yahoo.com.

“ The corneaswere beautifullyclear—in fact,noticeably clearerthan I am accustomed to withmy current phacomachines and settings.”

Robert J. Weinstock, M.D.

Clinical experience with transversal ultrasoundEarly experience with new ultrasound modality demonstrates impressively clear corneas on post-op day one

by Robert J. Weinstock, M.D.

Figure 1: Ellips adds a horizontal component to the traditional longitudinal movement of thephaco needle, creating an elliptical cutting pattern

Figure 2: Nuclear quadrant removal with Ellips Transversal Ultrasound

Refractive Cataract Surgery — Show Supplement • ASCRS Chicago 2008 11

Central to modern, state-of-the-art phacoemulsifica-tion surgery is the abilityto use fluidics to maintaina stable chamber. We

know that newer phaco deviceshave significantly reduced surge.

In a recent study, my col-leagues and I devised a way toobjectively compare the fluidics ofthe three latest-generation phacomachines: Infiniti (Alcon, FortWorth, Texas), Stellaris (Bausch &Lomb, Rochester, N.Y.), andWhiteStar Signature (AdvancedMedical Optics, AMO, Santa Ana,Calif.). Each device was first prop-erly primed and tuned. The phacotips of all three devices wereinserted into a single fresh, 81-year-old human eye bank eye. Thetips were inserted about 3.0 mminto the sclera, through watertightcorneoscleral tunnel incisionsplaced 90 degrees apart. We usedsimilar, non-ABS, 19-gauge tips foreach one.

To mimic post-occlusion surge,we set the vacuum pressure at 400mm Hg and the aspiration rate at40 mL/min. The irrigation bottleheight was 70 cm. The surge testwas performed with peristalticpumps, using no surge-controlmodes, and was repeated 20 times.

The anterior chamber depth ofthis eye was 4.1 mm. Averagechamber shallowing was 1.51 mmfor the Infiniti system, 0.83 mmfor the Stellaris, and 0.67 mm forthe WhiteStar Signature (Figure1), with tight standard deviationsacross the board (p<0.00001between the three machines).

At the high end of that spec-trum, chamber shallowing of 1.5mm, or nearly one-third of thetotal chamber depth, is certainlyproblematic. The WhiteStarSignature system was the most sta-ble platform, even without the flu-idics adjustments that surgeonswould use in the real world.

We also tested unoccludedflow by setting the bottle heightat 60 cm, aspiration rate at 60mL/min, and maximum vacuumof 550 mm Hg. The lower theunoccluded flow, the safer itshould be for the tip to approachthe capsule or iris.

The machine-indicated unoc-cluded vacuum at the tip rangedfrom 203.2 mm Hg for the INFINI-TI to 132.6 mm Hg for the White-Star Signature (Figure 2). Actualflow was closest to the machine-indicated levels for WhiteStar

Signature (58.5 mL/min), least forStellaris (53.5 mL/min), and inter-mediate for Infiniti (55.8 mL/min; p<0.00001 between the threemachines).

As cataract surgeons, we arelucky to have three outstandingphacoemulsification machinesavailable to us, and for many rou-tine cases, any one of thesedevices should perform well.However, in tough situations,there are statistically and clinicallysignificant differences amongthem. In our head-to-head, objec-

tive comparison, the WhiteStarSignature system provided the bestfluidics, both in terms of the low-est post-occlusion surge and thelowest unoccluded flow vacuum.

Randall Olson, M.D., is the John A.Moran Presidential Professor andChair of the Department ofOphthalmology and Visual Sciencesat the University of Utah HealthSciences Center. He is a consultantfor AMO. Contact him at 801-581-2352 orRandall.Olson@hsc.utah.edu.

“ In our head-to-head, objectivecomparison, theWhiteStarSignature systemprovided the bestfluidics, both interms of the lowestpost-occlusionsurge and the lowest unoccludedflow vacuum.”

Randall J. Olson, M.D.

Avoid the surge with premium fluidicsIn an objective, three-way fluidics comparison, the WhiteStar Signature phacoemulsification system produced the least amount of post-occlusion surge

by Randall J. Olson, M.D.

Figure 1: The WhiteStar Signature showed the least amount of chamber shallowing out of thethree machines, tested with an average of 0.67 mm

Figure 2: Actual flow was closest to the machine-indicated levels for the WhiteStar Signature,least for the Stellaris, and intermediate for the Infiniti

12 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

We have recently begunenrolling patients inan online patient reg-istry to track the out-comes of presbyopia-

correction IOL (PCIOL) implanta-tions. This registry is being con-ducted both nationally and inter-nationally at this time for theCustomMatch process whichinvolves implantation of either aReZoom or Tecnis MultifocalPCIOL (Advanced Medical Optics,AMO, Santa Ana, Calif.) in thefirst eye. After the first eye isimplanted, the same or a differentlens is placed in the second eyebased on patient feedback.

The online patient registry willinclude pre- and post-op patientquestionnaires on spectacle use atdifferent distances and also havethe patient evaluate glare andhalo. There will be pre- and post-op surgeon questionnaires measur-ing uncorrected visual acuity (far,near, and intermediate). Follow-upwill be six months after the lastpatient procedure.

For this trial, data is collectedin a prospective fashion. In gener-al, active patients who desire spec-tacle independence and who havea frequent demand for intermedi-ate vision (such as computer use)but who do not want to sacrificedistance vision do quite well withthe ReZoom IOL in both eyes. Forpatients with need for a closerworking range, a diffractive IOL inthe non-dominant eye may endup being preferred based onpatient feedback after the domi-nant eye is done.

The purpose of the registry isto collect data using a stagedapproach with patient feedback inbetween the IOLs and thereforeprovide surgeons with extra infor-mation on how these patients areperforming by monitoring overallsurgeon and patient satisfaction.

Staged implantationStaged implantation is a strate-

gy for effectively matching avail-able PCIOLs to each patient’s spe-cific needs. With CustomMatch,the patient receives a ReZoomrefractive presbyopic IOL in thefirst eye and then the surgeonmakes a decision on lens selectionfor the second eye based onwhichever technology matches thepatient’s needs. This customizedapproach to lens selection allowspatient participation in theprocess and provides a safety netbecause decisions are made in astep-wise approach, allowing the

flexibility to change course if nec-essary.

In my experience in the U.S.,about 90 to 95% of patients willbe satisfied with a bilateral“match” (the same IOL in eacheye). About 5 to 10% may do bet-ter with a mixed lens approachthat employs a different IOL prod-uct in each eye. Staged implanta-tion involves three steps: Implantthe primary IOL in the initial eye;assess the patient at one to twoweeks (acuity and satisfaction);

and then choose the fellow-eyeIOL based on patient feedback.

The registry results will pro-vide a validated roadmap forapplying multifocal IOL technolo-gy to best fit your patient needs. Ilook forward to sharing the resultsas they become available in thecoming months.

David R. Hardten, M.D., is a found-ing partner of Minnesota EyeConsultants, Minneapolis, Minn.Contact him atdrhardten@mneye.com.

Tecnis Multifocal Updateby Eric Donnenfeld, M.D.

In the recent U.S. clinical study, the Tecnis Multifocal intraocularlens (Advanced Medical Optics, AMO, Santa Ana, Calif.) demon-strated excellent visual acuity, reading acuity and speed, andpatient satisfaction. The investigational Tecnis Multifocal lens is athree-piece intraocular lens that is available on two different plat-

forms, a silicone platform as well as an acrylic platform. The opticalsurface of the lens has a full diffractive posterior surface which makesthe diffractive optics pupil-independent. One of the major advantagesof this lens is the addition of the wavefront-designed aspheric anteriorsurface. This is unique among all of the currently available lenses. Assuch, this lens targets zero spherical aberrations, which multiple studieshave shown provides peak visual performance (similar to what occursat age 19, when the average spherical aberration is 0.0 microns).

The trialThe multicenter, evaluator-masked comparative clinical evaluation

included 121 bilateral multifocal and 122 bilateral monofocal subjects,and was conducted at 13 investigational sites. Results are available atone year for 114 multifocal subjects. Subject assignment was based onpatient’s choice for a multifocal or monofocal IOL.

In the study, 94.6% of subjects indicated they would choose thelens again. Eighty-seven percent of subjects were 20/20 or betterBCDVA, while 94% of subjects were 20/32 or better with distance cor-rection at near. Ninety-three percent of subjects achieved simultaneous20/25 or better distance and 20/32 or better near. More than 84% ofpatients reported never wearing glasses post-implantation. Furthermore,compared to monofocal IOLs, the Tecnis Multifocal provides statistical-ly significantly improved reading acuity and speed.

“ In general,active patients whodesire spectacleindependence andwho have a frequent demandfor intermediatevision (such ascomputer use) butwho do not want tosacrifice distancevision do quite wellwith the ReZoomIOL in both eyes.”

David R. Hardten, M.D.

CustomMatch registry begins enrollmentOnline registry will track the outcomes of staging presbyopia-correcting IOL implantation based on patient needs and provide more data to doctors

by David R. Hardten, M.D.

The vast majority of subjects reported being able to function comfortably withoutglasses at all distances

Refractive Cataract Surgery — Show Supplement • ASCRS Chicago 2008 13

Patients implanted with theReZoom presbyopia cor-recting intraocular lens(PCIOL) (AdvancedMedical Optics, AMO,

Santa Ana, Calif.) report high sat-isfaction in 88% of cases, and 91%of patients have overall spectacleindependence at six months post-op, according to the CanadianOn-line Patient Registry (Figure1).

Twenty Canadian surgeonswere recruited and a goal to com-plete 100 to 150 bilateral patients,with six-week and six-month fol-low-ups, was set. Pre-op and post-op patient questionnaires on free-dom from glasses at different dis-tances, and pre-op and post-opsurgeon questionnaires measuringuncorrected visual acuity (far,near, and intermediate) were com-pleted. In addition, pre- and post-op patient questionnaires to eval-uate halos and glare, and potentialneuroadaption between six-weekand six-month follow-up visitswere given.

As of November 2006, 18 sur-geons had recruited patients forimplantation of bilateral ReZoomintraocular lenses. The ReZoomAdvisory Trial included hyperopic,presbyopic, and cataract patients.The target was emmetropia andthe goal was precise outcomes toachieve the benefits of multifunc-tional vision. One hundred andsixty-one patients were enrolled;106 patients had completed thesix-week post-op follow-up, and98 patients had completed the six-month post-op follow-up. The aimwas for the patient to be plano toslightly myopic to provide gooddistance vision for driving andfunctional near vision. Patientswith significant dry eye, cornealscarring, mild-to-moderatemyopia, pupil size less than 2.5mm, monofocal implant in thefirst eye, uncorrected post-opastigmatism greater than 0.5 D, orunstable capsular support wereexcluded.

Study findingsPatients had excellent far and

intermediate vision and good nearvision. Patients demonstratedimproved performance after bilat-eral implantation. Youngerpatients were found to havegreater spectacle independence. Atthe six-month mark, a higher per-

centage of patients were able toattain 20/20 vision.

We have found that patientneuroadaptation occurs betweenthe six-week and six-month fol-low-up visits. According to theregistry, surgeons indicated thatimportant factors in selecting amultifocal lens included distancequality vision, minimal amount ofhalos, near vision quality, minimalamount of glare, and intermediatequality vision. On average, around

66% of patients saw an improve-ment over time in halos and glare.Post-op visual quality issues, suchas glare and halo, resolve in themajority of cases and should notinhibit surgeons or patients fromselecting this lens (Figure 2).

George Beiko, BM, BCh, FRCS(C), isin practice in Ontario, Canada. He can be contacted at georgebeiko@hot-mail.com.

“ Patientsimplanted with theReZoom presbyopiacorrecting intraoc-ular lens (PCIOL)report high satis-faction in 88% ofcases, and 91% ofpatients have over-all spectacle inde-pendence at sixmonths post-op.”

George Beiko, BM BCh, FRCS(C)

Canadian long-term follow-up on refractive IOLsThe Canadian ReZoom registry outcomes show high satisfaction at six months

by George Beiko, BM, BCh, FRCS(C)

Figure 1: Post-op, patients are very satisfied and report high levels of overall spectacle independence with bilateral ReZoom implantation

Figure 2: 67% of patients saw an improvement over time in glare and halo by 6 months post-op

14 ASCRS Chicago 2008 • Show Supplement — Innovations in Corneal and Cataract Refractive Surgery

The new Tecnis one-pieceacrylic lens (AdvancedMedical Optics, AMO,Santa Ana, Calif.) com-bines the many benefits of

the Tecnis three-piece acrylic lenswith the ease of implantation of aone-piece platform.

Stable designThe Tecnis has a one-piece

acrylic construction with multiplepoints of fixation. This unique fixa-tion design allows the optic to staypositioned very tightly and closelyto the posterior capsule, away fromthe haptic plane. Therefore, whenit is placed in the bag it remainscentered. This provides additionalstability over traditional single-piece lenses. The result is a quickand long-term stabilization of theoptic and refraction.

The Tecnis one-piece also has acoplanar fixation so that the hap-tics are slightly offset from theoptic. This ensures the optic is posi-tioned very tightly and closely tothe posterior capsule, which mini-mizes posterior capsule opacifica-tion (PCO) and aids in centration.

Another benefit of this lensdesign is the 360-degree posteriorsquare edge. The barrier edgecontinues through the optic-hap-tic junction, which may minimizethat risk of PCO. Other availablesingle-piece lenses allow for lensepithelial cells to migrate alongthe haptic-optic junction and cre-ate posterior capsular opacifica-tion.

Additionally, the edges of theTecnis one-piece are frosted tominimize edge glare. The hapticloops are also highly polished,which allows the lens to unfoldgently and easily into the eye afterimplantation, even through anunenlarged, micro-coaxial phacoincision.

Acrylic materialStudies have shown that the

acrylic material used in the TecnisIOL is vacuole-free and has fewerglistenings. Other lenses with glis-tening formations have beenshown to affect visual acuity. Forexample, patients come in andthese little vacuoles or glisteningscan be seen at the slit lamp. If itgets to a moderate stage, objectivemeasurements in clinical trialshave shown with glistenings therecan be a loss of contrast anddecreased Snellen acuity.

In addition, with the Tecnisdesign there is no “cat-eye” reflexbecause of the curvature of thelens design, as well as the index of

the refraction of the material. Withthis lens there is minimal sphericalaberration and also minimal chro-matic aberration. When we weredoing the trials with this lens, wesaw some of the highest percent-ages of 20/20 visual acuities post-op out of many of the studiesbecause of this material.

Superior opticsThe anterior surface of the

one-piece has the same optics asthe Tecnis three-piece lens, allow-ing patients implanted with thenew lens design to experience thesame benefits. Studies havedemonstrated that youthful visionis better achieved when patientshave either zero to slightly nega-tive total ocular spherical aberra-tion post-op. The new one-pieceIOL is designed to reduce spherical

aberrations to essentially zero,thus improving quality of vision,night driving and safety in thevast majority of patients (Figures1 and 2).

Overall, the combination ofpremium optics, material, anddesign make the Tecnis one-piecea leap forward in one-piece IOLdesign. The benefits include sharp-er vision, ease of implantation,persistent centration, and longer-term clarity.

Y. Ralph Chu, M.D., is the founder ofthe Chu Vision Institute in Edina,Minn. He is also adjunct assistantprofessor of ophthalmology,University of Minnesota and clinicalprofessor of ophthalmology,University of Utah. Contact him at952-835-1235 or atyrchu@chuvision.com.

“ The combina-tion of premiumoptics, material,and design makethe Tecnis one-piece a leap forward in one-piece IOLdesign.”

Y. Ralph Chu, M.D.

Raising the bar for single-piece IOL design Next generation one-piece IOL combines superior optical quality with predictable, stable, and easy-to-implant design

by Y. Ralph Chu, M.D.

Figure 1: Population analysis reveals that the Tecnis lens offers the highest amount of spheri-cal aberration compensation, providing the vast majority of patients with between zero andslightly negative total ocular spherical aberration

Figure 2: In a clinical comparison of the three aspheric lenses on the market, the Tecnisproved better able to achieve post-op spherical aberration of essentially zero

Refractive Cataract Surgery — Show Supplement • ASCRS Chicago 2008 15

Intraocular lenses (IOLs) withnegative asphericity shouldplay a larger role in ophthal-mology practices than theycurrently do, according to our

theoretical calculations. Our stud-ies have shown that for normaleyes, the mean asphericity of anIOL should actually be around–0.35 microns to maximize visualquality.

Optimal qualityAlthough prior studies have

suggested that decentration ofIOLs with negative apshericity

would negatively impact qualityof vision, our studies demonstrat-ed that even with decentration ofas much as 0.5 mm, these lensesoutperform IOLs with either zeroasphericity or standard IOLs withpositive asphericity.

We also concluded that in eyesthat have undergone myopicexcimer laser procedures, the opti-mal mean asphericity of the IOLshould be –0.45 microns. On theother hand, for eyes that haveundergone hyperopic procedures,the optimal asphericity is zero.There is greater individual vari-ability in these groups compared

to virgin eyes.

AccommodationAnother advantage of an

aspheric IOL relates to pseudoac-commodation. In lenses with pos-itive asphericity, there is a hyper-opic shift as pupil size decreases(remembering that the refractivepower of the IOL increases fromcenter to periphery). For a reduc-tion in pupil size from 6 to 3 mm,the magnitude of this shift couldbe around 0.5 D. This will impairdepth of focus with accommoda-tive miosis.

On the other hand, the refrac-tive power of lenses with negativeasphericity does not change aspupil size increases or decreases.Thus we would expect that IOLswith negative asphericity shouldprovide greater depth of focusthan standard IOLs.

Although these studies arebased on sound theoretical calcu-lations, they are not clinical stud-ies. They also do not take intoaccount the very important, butnot yet well understood factor, ofthe role of neuroadaptation. Theremay be some neuroadaptiveprocesses that may alter theseresults slightly.

Overall, we are confident thatoptically this information repre-sents what will prove to be trueclinically.

Douglas D. Koch, M.D., is a profes-sor and the Allen, Mosbacher, andLaw Chair in Ophthalmology, CullenEye Institute, Baylor College ofMedicine, Houston, Texas. Contacthim at dkoch@bmc.tmc.edu.

“ Intraocularlenses (IOLs) with negativeasphericity shouldplay a larger role in ophthalmologypractices than theycurrently do.”

Douglas D. Koch, M.D.

Aspherical lenses offer added benefitsStudies indicate the benefits of aspheric lenses

by Douglas D. Koch, M.D., and Li Wang, M.D.

Figure 1: For normal eyes, the mean optimal IOL asphericity should be around –0.35 microns

Figure 2: An advantage of an IOL with negative asphericity is that refractive power does notdecrease as the pupil gets smaller

“ Our studies demon-strated that even withdecentration of asmuch as 0.5 mm, theselenses outperform IOLswith either zeroasphericity or standardIOLs with positiveasphericity.”

Douglas D. Koch, M.D.

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