intraocular lenses

INTRAOCULAR LENSESSIVATEJA CHALLA

OVERVIEW

HISTORICAL ASPECTS PRESENT DAY IOLs

Classification Design Material

PREMIUM IOLS PHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLs RECENT ADVANCES AND THE FUTURE

THE FIRST IOL!!

INSPIRATION Inertness of intraocular plexiglass shards A medical student, Steve Perry questioned him why was he not replacing the lens after removal

Approximately 1000 Ridley IOLs implanted in the next 12 years

Complications Disclocation : approx 20% Glaucoma : 10 % Uveitis

Went into disrepute Strongly opposed by Sir Duke-Elders

OVERVIEW

HISTORICAL ASPECTS

PRESENT DAY IOLs Classification Design Material


CLASSIFICATION

*Yanoff & Duker: Ophthalmology, 4TH ed. Table 5-2-1

First generation IOLs

Second generation IOLs Rigid and semi-rigid anterior chamber IOLs the anterior chamber, with fixation of the lens in the angle recess Baron, in France, is generally credited as being the first designer and

implanter of an anterior chamber lens

ADVANTAGES• Less decenteration• Decreased reaction

DISADVANTAGES• Corneal decompensation • Pseudophakic Bullous

keratopathy• Uveitis• Secondary glaucoma

Strampelli Tripod AC-IOL (1953) Choyce Mark I AC-IOL(1956)

Dannheim AC-IOL with closed haptics (1952)

Ridley Tripod AC-IOL (1957–60)

Third generation IOLs Iris suppoted lens Cornelius Binkhorst, Iris clip lens; four-loop (1957) Iridocapsular fixation; two loop (1965)

ADVANTAGES• Away from angle structures • Rate of dislocation was less• Less contact with corneal endothelium

DISADVANTAGES• Iris chaffing• Pupillary distortion• Transillumination defects• Chronic inflammation• CME• Distortion on pupillary dilatation• Endothelial decompensation

Binkhorst 4-loop lens (1957/58), Fyodorov iris clip Sputnik lens (1968)

Binkhorst 2-loop lens for iridocapsular fixation (1965).

Fourth generation IOLs Intermediate ACIOL Flexible loops with multiple point of fixation More stable Advantages – more stable, better design, less complications Disadvantages – anterior chamber is not the physiological site for

IOL

Kelman multiflex AC-IOL (1982)Kelman flexible Tripod AC-IOL (1981),

Intermedics Inc Dubroff AC-IOL (1981), Modern, one-piece, flexible PMMA AC-IOL (Kelman design) with Choyce foot plates

Azar 91Z AC-IOL (1982) ORC Inc Stableflex AC-IOL (1983)

Surgidev Inc Style 10 Leiske ACIOL (1978)

Fifth generation IOLsPMMA lenses Rigid posterior chamber IOL

Sixth generation IOLsFoldable IOL

Seventh generation IOLsMultifocal IOL

Eighth generation IOLsAccomodative IOLPhakic refractive IOL

ADVANTAGES OF IN-THE-BAG PLACEMENT

Proper anatomical site Intraoperative stretching or tearing of zonules is avoided Minimimal magnification (<2%); (20-30% aphakic glasses, 7-12%

aphakic contact lens, ACIOL 2-5% ) Low incidence of lens decentration and dislocation Maximal distance from the posterior iris pigment epithelium, iris

root, and ciliary processes Safer for children and young individuals Reduced posterior capsular opacification

DESIGN OPTIC

Part of the lens that focuses light on the retina.

HAPTIC Small filaments connected to the optic that hold the lens in place in the eye

HAPTIC

HAPTIC

OPTIC

HAPTIC DESIGN Plate haptic Loop haptic

C-loop J-loop Modifies C-loop

Plate-loop

Different types of haptic angulation relative to the plane of optic:-For posterior chamber lens:-100 anterior angulation to keep the optic part away from the pupil.For anterior chamber lens:-Posteriorly angulated lens to vault the intraocular lens away from the pupil

Square, truncated optic edge

LENS CHEMISTRY (Optic Materials)

RIGID MATERIALS PMMA

(Polymethylmethacrylate) Water content <1% Refractive index 1.49 Usually single piece

FLEXIBLE MATERIALS Silicones Acrylics

Hydrophilic Hydrophobic

RIGID MATERIALS

PMMA Poly metha methacrylic acid First material used Rigid inert and non auto clavable Chemically stable compound Excellent optical properties Refractive index 1.4Disadvantage Rigid and require larger incision

FLEXIBLE MATERIALS-SILICON Polymers of silicone and oxygen first material for foldable IOLs Hydrophobic (contact angle with water of 99°)ADVANTAGES Heat resistant, autoclavable, mouldable, compressible Highly transparent to visible light Excellent tensile and tear strength Extremely flexibleDISADVANTAGES Lower refractive index Can be pitted Slippery and cause glistenings

FLEXIBLE MATERIALS-HYDROPHOBIC ACRYLIC Copolymers of phenylethacrylate and phenylethylmethacrylate 3-piece or 1-piece designs Ref index 1.55ADVANTAGES Reduced rate of pco Higher refractive index thinner lens Good resistance to yag laserDISADVANTAGES Photopsias and Glistenings BSS packaging (reach 4% water content before implantation) Susceptible to mechanical damage by forceps

FLEXIBLE MATERIALS-HYDROPHILIC ACRYLIC hydroxyethylmethacrylate (poly- HEMA) and hydrophilic acrylic

monomer 1.43 RI, 38% water content ,1 piece design Small in dry state and swell on hydrationADVANTAGES Easiest to handle; less mechanical/YAG laser damage Less expensive Fold and unfold fasterDISADVANTAGES Higher PCO rate Low resistance to capsular contraction Calcium deposits

LENS CHEMISTRY (Haptic Material)

PMMA Polyimide (Elastimide) Polyvinylidene fluoride (PVDF)

OVERVIEW




PREMIUM IOLS MULTIFOCAL, ACCOMODATIVE, TORIC IOLs

METHODS

Monovision Multifocal IOL Accommodative IOL

RESTORATION OF ACCOMMODATION IN PSEUDOPHAKIA

MULTIFOCAL IOLs

Single IOL with two or more focal points

Types Refractive Diffractive Combination of both

REFRACTIVE MULTIFOCAL IOLs

Bull’s eye lens Concentric rings of different powers Central addition surrounded by distance optical power

Annulus design 3-5 rings Central for distance vision Near vision ring Distance vision ring

12345

Bright light/ Distance dominant zoneLarge Near dominant zone

Low light/ Distance dominant zone

Distance zone

Near zone Aspheric transition

REFRACTIVE MULTIFOCAL IOLs

Second-generation, refractive multifocal lens.

Aspheric transitions between zones provide intermediate vision

+3.50D at IOL plane +2.85D at the spectacle

plane

ReZoom

FDA approval in March 2005

DIFFRACTIVE MULTIFOCAL IOLs

Anterior aspheric surface : basic refractive power Multiple grooves on posterior surface : diffractive power

41% of light : distance 41% : near vision Pupil independent

Tecnis Multifocal IOLs (AMO) ZM900 (Silicone) ZA00 (Acrylic)

Optic Diameter 6.0 mm Optic Type

Modified prolate anterior surface Total diffractive posterior surface

FDA approval in January 2009

Acrysof IQ ReSTOR (Alcon) Acrylic diffractive multifocal IOL with apodized design Optic diameter- 6 mm Refractive for distance, and a diffractive lens for near. 16 rings distributed over central 3.6 mm Peripheral rings placed closer to each other Central rings : 1.3 µm elevated, near vision Peripheral 0.2 µm elevated, distant vision Anterior peripheral surface is modified to act as refractive

design Near Addition +3.0 D at IOL plane (+2.5 D at spectacle plane)

Apodization literally means "removing the foot“

To remove or smooth a discontinuity at the edges

COMBINATION OF BOTH

Refractive lenses (pupil dependent) ideal for Light to moderate

readers Drive mostly during

the day. Play sports, Use a computer

frequently, or Activities that rely

heavily on intermediate vision

Diffractive IOLs (pupil independent)for Spend a lot of time

reading Detailed craft-work Scotopic activities

MoviesNight time driving

REFRACTIVE MULTIFOCAL IOLS

DIFFRACTIVE MULTIFOCAL IOLS

Excellent intermediate and distance vision Excellent reading vision and very good distance vision

Near vision fair but may not be sufficient to see very small print

Fair Intermediate vision

Patients who read for prolonged periods of time or in poor lighting may experience eye fatigue.

Patients who do lots of computer work may not accept it well

PUPIL DEPENDENT LESS DEPENDENT ON PUPIL

PATIENT SELECTION FOR MfIOLs(most important factor)

Strong desire to be spectacle independent Functional & occupational requirements

Occupational night drivers (avoid) Pre-existing ocular pathologies Hypercritical & demanding patients

strictly avoided > 1.0 D astigmatism; irregular astigmatism (avoid) Individuals with a monofocal lens in one eye History of previous refractive Surgery Previous PK Chances of IOL dislocation

INTRAOPERATIVE EXCLUSION

Significant vitreous loss during surgery Pupil trauma during surgery Zonular damage Capsulorhexis tear Capsular rupture Eccentric CCC

SPECIAL CONSIDERATIONS FOR MfIOLS

Counselling (most important) Accurate Biometry Power Calculation Surgical Technique

Round, centered CCC completely overlapping the lens optic Removal of all viscoelastic from behind the lens

DISADVANTAGES

Loss of contrast sensitivity Glare and halos

scattering of light at the dividing line of the different zones improves with bilateral implantation, because of “a bilateral

summation” effect Less satisfactory visualization of fundus- difficulty in vitreo-retinal

procedures Requires neuro adaptation

ACCOMMODATIVE IOLs Monofocal IOL Changes position inside the eye as the eye's focusing muscle

contracts 1 mm of anterior movement of lens = 1.80 D of accommodation Mimicking the eye's natural ability to focus

Silicone Crysta lens (B & L)

• Hydrophilic Acrylic• BioComFold ( Morcher GmbH) • 1CU (Human Optics AG)• Tetraflex ( Lenstec Inc.)

CrystaLens The lens is hinged adjacent to the optic

with accommodative effort▪ redistribution of ciliary body mass▪ result in increased vitreous pressure ▪ move the optic forward anteriorly within the visual axis▪ creating a more plus powered lens

Akkolens Synchrony Dual-Optic IOL (Visiogen)

NuLens(Israel) FluidVision IOL

Smaller optic-more aberrations

Failure of accommodation due to

Fibrosis

Capsular opacification

Anterior

Posterior

Costly

DISADVANTAGES

TORIC IOLs Modern cataract surgery is more of refractive surgery. Myopia & hypermetropia can be corrected using appropriate

spherical powers of IOL’s. 20% of patients who undergo cataract surgery have 1.25D of

corneal astigmatism or more. It can be corrected with Toric IOL’s.

Vision with Cataract and Astigmatism

Cataract corrected with IOL but Astigmatism remaining

Cataract and Astigmatism both corrected with Toric IOL

Designed to correct astigmatism Axis of toric power is designed with 2 small hash-marks Pre-operative marking of steep axis (greater curvature) of cornea (in

sitting position) Per-operative alignment of lens with corneal marking 1º misalignment ~ 3.3% loss of cylindrical power Proper positioning of IOL is a must Postoperatively 20% IOL’s rotated > 30 degrees and 50% IOL rotated

about 10 degrees.

Two Types Silicone

STAAR Toric IOL (STAAR Surgicals) Cylindrical powers: 2.0 D and 3.5 D

Acrylic

AcrySof Toric IOL and Acrysof IQ Toric IOL (Alcon Labs) Cylindrical powers of 1.5 D, 2.25 D, and 3.0 D

T-flex (Rayner) 1.0 to 11.0 D in 0.25 D steps

Acri.Comfort (Zeiss)

Proposed incision is marked at the steepest plus meridian.

IOL is loaded into the injection cartridge with the toric marks on the anterior surface

IOL is implanted in the capsular bag and axis is aligned

Remove OVD from behind the IOL For every 1 degree of axis rotation, 3.3% of the lens cylinder power may be lost. At 30 degrees, all effect is lost

Factor Affecting Rotation of Toric IOL(1) IOL Material- Hydrophobic Acrylic < Hydrophilic Acrylic < PMMA < Silicon(2) Overall IOL diameter - Larger diameter prevents rotation .nowadays in

11-13 mm overall diameter. (3) Haptic Design- Initial concept - Loop haptics prevent early rotation . - Plate haptics prevent late rotation. Recent concept – No difference in incidence of post operativerotation between plate and loop haptics provided material ofboth loop and plate is same.

Patient selection

Regular corneal astigmatism > 1.5 D

Vision compromising cataract

Patient wants spectacle independence

AcrySof Toric IOL Calculator compensates for surgically induced astigmatism

Data input Patient data Keratometry IOL spherical power Surgically induced astigmatism Incision location

Remember…

B/L Toric IOL’s give high level of spectacle independence(97%). Requirement of near correction can be overcome by multifocal

toric IOL(AcriLisa multifocal toric IOL) Well centered rhexis with diameter 5- 5.5 mm with 360 degrees

overlap of IOL margin Cohesive viscoelastics are preferred Remove OVD from behind the IOL If any compromise of zonular integrity or capsule occurs please

switch to standard non toric IOL POST OP AXIS ALIGNMENT-Realignment should be done in < 2 wks

OVERVIEW



PREMIUM IOLSPHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLs RECENT ADVANCES AND THE FUTURE

PHAKIC IOLS

Implantation of IOL without removing natural crystalline lens. ADVANTAGE: Preserves natural accommodation

Mostly used in Myopic eyes: -5 to -20 DS Also used in Hyperopic eyes

Concern in Hyperopes: More chances of endothelial damage Increased risk of angle closure glaucoma

Life-long regular follow up required.

Posterior Chamber

Iris fixated

Angle fixated

• Implantable collamer lens (ICL) (VISIAN; STAAR)• Phakic refractive lens (Mellennium)• Sticklens

• VERISYSE/ARTISAN (AMO/OPTECH)

• 4 point fixation• Baikoff’s modification of Kelman type

haptic design• NuVita MA20 (Bausch and Lomb)

• 3 point fixation• Vivarte (IOL Tech)• Separate optic and haptic

PC PHAKIC IOL

• Pre-crystalline lens made of silicone or collamer.

• white-to-white limbal diameter - 0.5 mm

COMPLICATIONS:• Constant contact

pressure • Cataract• Ciliary body

reactions• Prevent free

passage of aqueous.- Iridectomy required

IRIS FIXATED

• Made of PMMA• convexo-concave• Haptics fixed to iris –

claws• ADVANTAGES OVER ICL:

• Customized smaller size possible

• Easier examination from end-to-end

• COMPLICATIONS- • Early post op AC

inflammation• Glaucoma• Iris atrophy on

fixation sites• Implant dislocation• Decentration• Endothelial cell loss

ANGLE FIXATED

• COMPLICATIONS –• Endothelial cell

loss• Irregular pupil• Iris

depigmentation• Post-op

inflammation• Halos and glare• Surgical induced

astigmatism

ASPHERIC IOLS Human eye : Aspheric Optics Cornea : Positive spherical aberration Young crystalline lens : Negative

spherical aberration Ageing crystalline lens : Increased

positive spherical aberration

HOW TO OVERCOME ? Strategy 1:

Lens with negative spherical aberrations to balance the normally positive corneal spherical aberrations

Strategy 2: Lens with minimum spherical aberrations so that no additional

spherical aberration is added to the corneal spherical aberrations

Conventional IOL increasethe spherical aberration of the eye

Aspheric IOLs attempt to improve pseudophakic vision by controlling spherical aberrations

Anterior prolate surface Tecnis, Advanced Medical Optics (AMO)

Posterior prolate surface Acrysof IQ, Alcon Laboratories

Both Anterior and Posterior prolate surfaces Akreos AO, SofPort AO and L161 AO, Bausch & Lomb

ASPHERIC IOLs Need perfect centration Decreased depth perception More expensive Need corneal topography for

optimal results Not much difference in

photopic conditions and in older age group

Not for previous hyperopic refractive surgery

Better contrast sensitivity Better mesopic vision Night time driving AcrySof® IQ Aspheric IOL

Better option for younger patients

SPECIAL TYPESANIRIDIA IOLs Scleral fixation (suture/glue) DRUG ELUTING IOLs

PIGGYBACK IOLs

OVERVIEW



PREMIUM IOLS PHAKIC AND ASPHERIC IOLSCOMPLICATIONS RELATED TO

IOLs RECENT ADVANCES AND THE FUTURE

COMPLICATIONS RELATED TO IOLs MALPOSITIONS

Pupil capture Decentration Windshield wiper syndrome Sunset syndrome

PCO Dysphotopsias

Positive : night time glare and halos Negative : black ring more towards temporal field

IOL material : acrylic > silicone Refractive index : negative dysphotopsia more with higher refractive

indices

OVERVIEW



PREMIUM IOLS PHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLsRECENT ADVANCES AND THE

FUTURE

RECENT ADVANCES AND FUTURE

LIGHT ADJUSTABLE IOL TELESCOPIC IOLs SMART IOLs ELECTRONIC IOLs

LIGHT ADJUSTED IOLS Calhoun's light adjustable IOL.

SMART IOL

TELESCOPIC IOLs Miniature implantable Galiliean telescope Implanted in posterior chamber Held in position by haptics loops Contain number of microlenses which magnify objects in the central

visual field. Improves central vision in ARMD

Diseased eye: Image focused on damaged macula

Implanted eye: Image focused on macula and periphery

DRAWBACKS:

Surgically more challenging Difficulty due to the size and weight of the

implant Endothelial compromise Blocked peripheral retinal visibility Difficulty in future retinal laser treatments Loss of peripheral vision

ELECTRONIC IOL World's first implantable lens with artificial

intelligence.CONCEPT: The pupil responds to accommodation by getting smaller. The IOL includes sensors that detect very small changes in pupil size. The pupillary response to accommodation is different from the pupillary response to light in regard to amplitude and how rapidly it occurs in response to accommodation.

Electro-active switchable elementChange in the molecular configuration of the liquid crystal to alter the optical power of the lensAutomatically adjusts focusing power electronically, in millisecondsMaintains constant in-focus vision for various distances and light environments. Controlled by a micro-sized power-cell with an expected >50 year rechargeable cycle life.

LENS: Set to correct distant vision (with dilated pupil)

AUTO FOCAL LENS: Electro-active liquid crystal centre for near vision (with small pupil)

BATTERY: Rechargeable Li-ion battery

MICRO CHIP: Regulates the auto-focal lens

PHOTO SENSOR: Detects the external light

FRONT (CUT-AWAY) VIEW OF ELENZA®

ELECTRONIC IOL

Remaining safety and technological issues… What happens to the electronic

components if the lens is hit with a YAG

laser ???

Are any of the materials toxic ???

What if there's leakage ???

THANK YOU

intraocular lenses

Health & Medicine