Intraocular lenses
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Transcript of 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
OVERVIEW
HISTORICAL ASPECTS PRESENT DAY IOLs
Classification Design Material
PREMIUM IOLS PHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLs RECENT ADVANCES AND THE FUTURE
K
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
PREMIUM IOLS PHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLs RECENT ADVANCES AND THE FUTURE
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
HISTORICAL ASPECTS PRESENT DAY IOLs
Classification Design Material
PREMIUM IOLS PHAKIC AND ASPHERIC IOLS COMPLICATIONS RELATED TO IOLs RECENT ADVANCES AND THE FUTURE
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
HISTORICAL ASPECTS PRESENT DAY IOLs
Classification Design Material
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
HISTORICAL ASPECTS PRESENT DAY IOLs
Classification Design Material
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
HISTORICAL ASPECTS PRESENT DAY IOLs
Classification Design Material
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