MicrophacoThe next frontier in Cataract Surgery

Dr Keiki R. MehtaDr Cyres K. MehtaDr Cyres K. Mehta

Mehta International Eye Institute

Colaba Eye Hospital

Breach Candy Hospital

Mumbai India

The new medium

• Phacoemulsification has proven to be aboon to the Ophthalmic world and tocataract patients. Both have prospered .cataract patients. Both have prospered .

• However one has to always push theenvelope if further heights are to beachieved. The advent of Microphako truly anew horizon

Microphako

• The term includes all surgeries done in lessthan 2.0 millimeter incision or as is popularlytermed. Sub 2 phacotermed. Sub 2 phaco

• Essentially it involves the use of bimanualphako with a naked or tightly sleeved phako tipwith an irrigating chopper or an regularchopper with a third irrigation ( Blumenthal )type port

Bimanual phaco

• by Steven P. Shearing, MD, a cataractsurgeon in Las Vegas, Nev. has beencredited as the first to do this type of surgeryin 1982in 1982

• Many workers on bimanual phako havemade this now an acceptable procedurePackard , Randy Olsen, Howard Fine , BarrySiebel, Jack Dodick and Agarwal have allmade significant contributions.

What led to Microphaco

• Three simultaneous developments wererequired before this concept of microphacocould be launched .

• An re-application of the concept of bimanual• An re-application of the concept of bimanualphaco

• Improvements in the machines..AllerganWhitestar, Alcon Advantec , to use microburstpower which would permit the use of anunsleeved or tightly sleeved needle.

• The advent of the ultra thin foldable IOL

The Machines

• “WhiteStar technology, a new rapid-pulsedphaco system that permits cataract surgerywith reduced heat, may be ideally suited towith reduced heat, may be ideally suited tosmall-incision surgery Because of its abilityto pulse much more rapidly, this technologyis capable of giving us coldphacoemulsification

The Alcon Legacy Advantec• The AdvanTec hardware and software

reduces the amount of energy entering theeye by allowing the Legacy to deliverbursts of energy — in short or long pulses— with variable periods of rest.— with variable periods of rest.

• The software allows customized settingsand automated modes of chopping thatreduce chatter and energy. This reductionin energy allows harder cataracts to betackled with greater ease. The NeoSoniXhandpiece oscillations reposition the lenstissue on the tip, swiftly breaking up thenuclear fragments

The Millennium MicrosurgicalSystem

• The Millennium Microsurgical Systemfrom Bausch & Lomb has three notablefeatures: its Dual Linear Control,Concentrix fluidics control technology andConcentrix fluidics control technology andmicro-phaco burst capabilities.

• The new Millennium system includesenhanced ultrasonic drivers, giving morecontrol of the ultrasound with pulse andmicro-phaco burst modes

STAAR Surgical’s SonicWave

• STAAR Surgical’s SonicWave phacoemulsificationsystem takes a different approach to lens fragmentation.The SonicWave uses sonic energy in the range of 40 Hzto 400 Hz in addition to the 40,000 Hz range thatultrasonic phaco machines generally employ.The lowerultrasonic phaco machines generally employ.The lowerenergy generally produces less heat, reducing the risk ofcorneal burns. The SonicWave can be switched betweensonic and ultrasonic modes with a foot pedal.

• The SonicWave also employs, the UltraVac coiled tubingwhich is designed to stabilize the anterior chamber andto prevent post-occlusion surge, which can causeanterior chambers to dimple and collapse

Dodick ARC PhotoLysis

• This phacoemulsification system (ARC LaserCorporation uses an Nd:YAG laser instead ofultrasound to break up a cataractous lens “It isimpossible to produce a corneal-scleral burnimpossible to produce a corneal-scleral burnwith this laser apparatus,” Dr. Dodick said inan interview. “Also, the infusion can beseparated from the laser emulsifying probe,thus making it possible to perform theoperation through two 1.2-mm incisions

The SIStem (Solutions InSurgery) Phacoemulsification

System by Paradigm• The SIStem (Solutions In Surgery)

Phacoemulsification System by Paradigm iscomparable to other microsurgical systems.The Paradigm SIStem employs a mini-.The Paradigm SIStem employs a mini-peristaltic pump and advanced hydrodynamics,allow good chamber stability. the VRT feature,which allows parameters to change andincrease flow and vacuum during a case onceocclusion is achieved. This allows for veryefficient attraction of peripheral wedges ofnucleus to the center for emulsification

• However by far the greatest• However by far the greatestadvance is in the field ofthe rollable or foldableIOL.

ThinOptX® Ultra-small incisioncataract lenscataract lens

MicrophacoThe next frontier in Cataract Surgery

ThinOptX® Ultra-small incisioncataract lenscataract lens

ThinOptX® Optics

• The power of the lens is determined by thedifference in curvature between the anterior andposterior surface. The ultra-thin lens byThinOptX® is manufactured by lathe cutting oneThinOptX® is manufactured by lathe cutting onesurface to retain a continuous curvature and/ororientation as traditional lenses, while the secondsurface is maintained within microns of theopposite surface. A series of steps 50 microns inheight are lathe cut into the second surface to keepthe lens thin.

Surface curves• A lens in theory, approaches perfection as the

thickness approaches zero. A traditional lens is aportion of a sphere that has the same radiusregardless of the distance from the central axis.

The ThinOptX® lens is manufactured so that theThe ThinOptX® lens is manufactured so that thesecond surface curves are different at eachstep/ring. Each step can, therefore, be focused on asingle focal point, which should eliminatespherical aberration. As a result of this lensdesign, the implant can be folded or rolled to beinserted through an ultra-small incision (less than2.0-mm).

ThinOptx is an refractive IOL

• The normal lines on the back surface of theFresnel Lens do not originate from the same point;therefore, the back surface of the lens functions asa series of prisms. By selecting the angle thea series of prisms. By selecting the angle theincoming light rays make with the normal line ofeach prism, one can choose the focal pattern of theresulting light. One such application is theheadlamps of an automobile. The second surfaceof the ThinLens is designed to assist the frontsurface in focusing the light at a single point,which by definition is a REFRACTIVE lens(fig.1b).

The rings in the ThinOptx IOL

• With the ThinLens technology each ring has anexposed edge of 50-microns or less. On averagethere are three rings per lens plus the outer edge ofthe lens. The cumulative ring edges are 200-the lens. The cumulative ring edges are 200-microns. This is much less area than a standard ormeniscus lens. But to quote an old saying "Theproof is in the pudding." To date NOT ONEPATIENT has complained of glare or halos, evenunder low light conditions

Advantage of the thinness ofThinOptx

• The ThinLens is so thin the error goes away. Witha central axis thickness of 50-micron for ameniscus lens and 300-micron for a bi-convex orplano optic, there is little error in measuring theplano optic, there is little error in measuring thelens due to thickness.

• With the ThinLensTM one can measure lensdesigned to the same power without adjusting thelens bench. The thinness is one of the reasons theThinLensTM can be manufactured in 1/8-diopterincrements.

Fresnel V/s Refractive IOL

Spherical Aberrations

• Spherical Aberrations, as the term implies,are aberrations from the fact that lens aremost often designed as a portion of asphere. For a theoretically perfect lens thesphere. For a theoretically perfect lens theradius of the lens surface should increase asthe distance from the central axis increases.The lens should be aspheric.

Spherical abberation• A sphere is not a perfect lens model. The error can

be as much as 1.5-diopter when measured 2-millimeters from the central optic. The majority ofcataract lenses are manufactured with sphericalaberrations. The standard aperture on a lens benchis approximately 3-millimeters. Many lensmanufacturers will not have acceptable optics ifmanufacturers will not have acceptable optics ifthe apertures were opened to 4-millimeters.

The ThinOptX® lens is manufactured to eliminatemost of the spherical aberrations. Each curve onthe back has a slightly different radius. The slightchange in curvature on each back surface willassure one focal point.

Other Aberrations

• Thickness causes a form of aberration due to light raystraveling longer in the thicker portion of the lens. Theerror is additive to spherical aberrations, but is small if thelens manufacturer controls the thickness of the lens orcompensates for the differences in thickness whenmeasuring the lens.

The ThinLens is so thin the error goes away. With acentral axis thickness of 50-micron for a meniscus lensand 300-micron for a bi-convex or plano optic, there islittle error in measuring the lens due to thickness. In factwith the ThinLensTM one can measure lens designed tothe same power without adjusting the lens bench. Thethinness is one of the reasons the ThinLensTM can bemanufactured in 1/8-diopter increments.

Abberations in normal IOL’s

• The diagram in fig. 2illustrates an eye andlens. The light hits theedge of the lens and isedge of the lens and isreflected unfocusedinto the eye. With thecondition, halo,streaks and a generalloss of contrast wouldseem logical.

Glare

• In laboratory work, extreme edge glare wasencountered when a light source was placed near athick flat piece of plastic. The large edges werecovered and never exposed to direct light rays. Ancovered and never exposed to direct light rays. Anextremely small angle of incidence was created.The absorbed light hit the large edge and wasreflected back across the sheet of plastic to theopposite edge. The light in the lens gave theappearance of a laser generation tube. When thelight source was removed the glare faded away.

Thinoptx parameters

• Thinoptx, 30-350micron IOL!

• Power: –25 to +30

• 1 piece HEMA IOL• 1 piece HEMA IOL

• Length 11.2 mm

• Optic: 5.5mm

• A: 118.94

• Thickness: 30-350microns

ThinOptx particulars

• The teardrops fenestrationholes in the plate hapticsalways have the teardroppointing in the clockwisedirection to assure thedirection to assure thecontinuous curved surfaceis resting against theposterior capsule. The tipsof each haptic are verythin. The overall length ofthe lens is 11.2millimeters.

ThinOptx particulars

• The haptic footplates are50 microns thick from10.0 millimeters to the tipof each haptic. Theof each haptic. Theextremely thin haptic tipsallow the tip to roll orcurl,. The rolling createsvery little force on thecapsular sack or the lens

Refraction sites

• Refraction takes placeindividually at eachsegment. Thus there isno chance of a blurno chance of a blurdeveloping .

Initial entry

• A 26-gauge needlewith viscoelasticmaking an entry inthe area where thethe area where theside port is. This isfor entry of theirrigating chopper.

Corneal incision

• Clear cornealincision made withthe keratome (0.9mm). The oval irisrepositor stabilizesthe eye

Rhexis

• Rhexis started witha needle. Better toa needle. Better touse a good bore asit enhances theflow. Alternativelyuse icedmethylcellulose

Chopping commenced

• Initial chops beingmade with theirrigating chopper

• Note 1.9 mm• Note 1.9 mmphaco probewithout sleeveinside the eye.

Chopping proceeding

• Note thecrackscreated byvertical chopping.The assistant mustThe assistant mustcontinuouslyirrigates the phacoprobe area fromBSS to preventcorneal burns.

Chopping the nucleus

• Chopping proceeding.Note The nucleusshould be graduallychopped into smallerchopped into smallerand smaller bits fromthe periphery. Thatway control ismaintained.

VIDEO PLEASE

.

Completion of phaco

• The proceedure iscompleted. Now I/Acan proceed. Thereis no need tois no need tochange theinstrumentation alI/A handpieces arean asset.

I/A completed.

• Bimanual irrigationaspirationcompleted.

ThinoptX IOL

• ThinOptX IOL fromthe bottle.

• It may be insertedusing a injector orusing a injector orsimply rolled andinserted with a longtipped smoothforceps

Manual insertion of the ThinOptx

• IOL held in asmooth forcepssimply insertedinto the eye . Onlyinto the eye . Onlysectret is to usefrozenmethylcellulose to‘roll’ the IOL.

Positioning the IOL

• The IOL is movedinto the capsularbag prior letting itunfurl or open up.unfurl or open up.

IOL unfurls.

• Notice the IOL iscommencing tounfurl . Withunfurl . Withmethylcellulose ittakes far longer thanwith Healon

Unfurled IOL

• Lens in good position .Always wiser to use amiotic and narrow thepupil prior leaving thepupil prior leaving thecase.

Choppers for bimanual use

• Available chopperswith irrigation. Theauthor uses a Katenachopper as a routinechopper as a routinefor these cases.

• Now also available atIndo German India

Final step

• Viscoelasticremoved usingbimanual irrigationaspiration probesaspiration probes

• Lens continues tounroll in the eye.

The ThinOptx IOL

Vision corrected

4th day post-op

6/6 34 89.4%

6/9 3 7.8%

6/12 1 2.8%

The ThinOptx IOL

Vision corrected

one month post-op

6/6 36 94.7%6/6 36 94.7%

6/9 2 5.3%

Caution : Cases carefully selected : Results may bebiased

MIcrophaco

Summary• A new technique of bimanual phaco has to be

mastered

• A new machine has to be purchased with its• A new machine has to be purchased with itsappropriate features

• A new lens, which is stable and easy to insert,may solve the problem of decentrage followingbag contraction over time.

• Long time studies required prior formalacceptance of this new technique

ThinOptX® Ultra-small incisioncataract lenscataract lens

ThinOptX® Optics

• The power of the lens is determined by thedifference in curvature between the anterior andposterior surface. The ultra-thin lens byThinOptX® is manufactured by lathe cutting oneThinOptX® is manufactured by lathe cutting onesurface to retain a continuous curvature and/ororientation as traditional lenses, while the secondsurface is maintained within microns of theopposite surface. A series of steps 50 microns inheight are lathe cut into the second surface to keepthe lens thin.

Surface curves• A lens in theory, approaches perfection as the

thickness approaches zero. A traditional lens is aportion of a sphere that has the same radiusregardless of the distance from the central axis.

The ThinOptX® lens is manufactured so that theThe ThinOptX® lens is manufactured so that thesecond surface curves are different at eachstep/ring. Each step can, therefore, be focused on asingle focal point, which should eliminatespherical aberration. As a result of this lensdesign, the implant can be folded or rolled to beinserted through an ultra-small incision (less than2.0-mm).

ThinOptx is an refractive IOL

• The normal lines on the back surface of theFresnel Lens do not originate from the same point;therefore, the back surface of the lens functions asa series of prisms. By selecting the angle thea series of prisms. By selecting the angle theincoming light rays make with the normal line ofeach prism, one can choose the focal pattern of theresulting light. One such application is theheadlamps of an automobile. The second surfaceof the ThinLens is designed to assist the frontsurface in focusing the light at a single point,which by definition is a REFRACTIVE lens(fig.1b).

The rings in the ThinOptx IOL

• With the ThinLens technology each ring has anexposed edge of 50-microns or less. On averagethere are three rings per lens plus the outer edge ofthe lens. The cumulative ring edges are 200-the lens. The cumulative ring edges are 200-microns. This is much less area than a standard ormeniscus lens. But to quote an old saying "Theproof is in the pudding." To date NOT ONEPATIENT has complained of glare or halos, evenunder low light conditions

Advantage of the thinness ofThinOptx

• The ThinLens is so thin the error goes away. Witha central axis thickness of 50-micron for ameniscus lens and 300-micron for a bi-convex orplano optic, there is little error in measuring theplano optic, there is little error in measuring thelens due to thickness.

• With the ThinLensTM one can measure lensdesigned to the same power without adjusting thelens bench. The thinness is one of the reasons theThinLensTM can be manufactured in 1/8-diopterincrements.

Fresnel V/s Refractive IOL

Spherical Aberrations

• Spherical Aberrations, as the term implies,are aberrations from the fact that lens aremost often designed as a portion of asphere. For a theoretically perfect lens thesphere. For a theoretically perfect lens theradius of the lens surface should increase asthe distance from the central axis increases.The lens should be aspheric.

Spherical abberation• A sphere is not a perfect lens model. The error can

be as much as 1.5-diopter when measured 2-millimeters from the central optic. The majority ofcataract lenses are manufactured with sphericalaberrations. The standard aperture on a lens benchis approximately 3-millimeters. Many lensmanufacturers will not have acceptable optics ifmanufacturers will not have acceptable optics ifthe apertures were opened to 4-millimeters.

The ThinOptX® lens is manufactured to eliminatemost of the spherical aberrations. Each curve onthe back has a slightly different radius. The slightchange in curvature on each back surface willassure one focal point.

Other Aberrations

• Thickness causes a form of aberration due to light raystraveling longer in the thicker portion of the lens. Theerror is additive to spherical aberrations, but is small if thelens manufacturer controls the thickness of the lens orcompensates for the differences in thickness whenmeasuring the lens.

The ThinLens is so thin the error goes away. With acentral axis thickness of 50-micron for a meniscus lensand 300-micron for a bi-convex or plano optic, there islittle error in measuring the lens due to thickness. In factwith the ThinLensTM one can measure lens designed tothe same power without adjusting the lens bench. Thethinness is one of the reasons the ThinLensTM can bemanufactured in 1/8-diopter increments.

Abberations in normal IOL’s

• The diagram in fig. 2illustrates an eye andlens. The light hits theedge of the lens and isedge of the lens and isreflected unfocusedinto the eye. With thecondition, halo,streaks and a generalloss of contrast wouldseem logical.

Glare

• In laboratory work, extreme edge glare wasencountered when a light source was placed near athick flat piece of plastic. The large edges werecovered and never exposed to direct light rays. Ancovered and never exposed to direct light rays. Anextremely small angle of incidence was created.The absorbed light hit the large edge and wasreflected back across the sheet of plastic to theopposite edge. The light in the lens gave theappearance of a laser generation tube. When thelight source was removed the glare faded away.