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INTRAOCULAR LENSES
OVERVIEW • HISTORICAL ASPECTS
• PRESENT DAY IOLs
– Classification
– Design
– Material
• ASPHERIC IOLs
• MULTIFOCAL, ACCOMO...
HISTORICAL ASPECTS
The Evolution of Intraocular Lenses*
*Yanoff & Duker: Ophthalmology, 3rd ed. Table 5-2-1, pg 394
HISTORY
• First IOL implantation
– Sir Harold Ridley
• November 29, 1949 at St. Thomas Hospital, London
• 49 year woman
• ...
– INSPIRATION
• Inertness of intraocular plexiglass shards
• A medical student, Steve Perry questioned him why was he not
...
EARLY ANTERIOR CHAMBER IOLs
• Rigid or semirigid AC-IOL
– Baron, in France; May 13, 1952
– Scharf and Strampelli
• Flexibl...
– Barraquer
• Open-loop AC-IOL with J-haptics
• Nylon haptics
– Complications
• High vaulting
– Late endothelial atrophy,
...
ADVANTAGES
• Less decenteration
• Decreased reaction
DISADVANTAGES
• Corneal decompensation
• Pseudophakic Bullous
keratop...
IRIS-SUPPORTED LENSES
• Epstein, 1953
– Collar stud lens
– Maltese cross lens
– Copeland lens
• Iris pigment epithelial de...
• Cornelius Binkhorst,
– Iris clip lens; four-loop (1957)
– Iridocapsular fixation; two loop (1965)
• Forerunner to capsul...
• Jan Worst (Holland)
• Medallion IOL, mid-1970s
– Eliminating the anterior haptics while
retaining the horizontally orien...
• Iris claw lens (lobster claw); by Worst in 1978
– Artisan/Artiflex Lens
– Slits in both haptics
– Clamped into the mid-p...
ADVANTAGES
• Away from angle structures
• Rate of dislocation was less
• Less contact with corneal
endothelium
DISADVANTAG...
INTERMEDIATE ACIOLs
• Improved manufacturing techniques
– Tumble polishing of IOLs
• Flexible loops with multiple point of...
Kelman multiflex AC-IOL (1982)
Kelman flexible Tripod AC-IOL (1981),
Intermedics Inc Dubroff AC-IOL (1981),
Modern, one-pi...
• PHACOEMULSIFICATION
• SOPHISTICATED MICROSURGERY
• OPHTHALMIC VISCO-SURGICAL DEVICES
• CONTINUOUS CURVILINEAR CAPSULORRH...
• Rigid tripod design (John Pearce)
• J-looped PCIOL (Steven Shearing)
• Modified J-looped PCIOL (Sinskey)
• C-looped PCIO...
ADVANTAGES OF IN-THE-BAG PLACEMENT
• Proper anatomical site
• Symmetrical loop placement
• Intraoperative stretching or te...
MODERN IOLs
PRESENT DAY IOLs
• Classification
• Design
• Material
CLASSIFICATION
INTRAOCULAR LENS DESIGN
• Single piece / monobloc
• Plate haptic / open loop haptics
• Angulated / planar haptics
• Edge d...
ANGULATED HAPTICS ALLOW FOR ADEQUATE PUPILLARY
CLEARANCE AND ADHESION TO THE POSTERIOR CAPSULE
• Square, truncated optic edge
HAPTIC DESIGN
• Plate haptic
• Loop haptic
– C-loop
– J-loop
– Modifies C-loop
• Plate-loop
LENS CHEMISTRY
(Optic Materials)
• RIGID MATERIALS
– PMMA
(Polymethylmethacrylate)
– Water content <1%
– Refractive index ...
FLEXIBLE MATERIALS
• Silicone
– Polymers of silicone and oxygen
– Since 1984; first material for foldable IOLs
– Hydrophob...
HYDROPHOBIC ACRYLIC
• Copolymers of acrylate and methacrylate
• 1993 (Acrysof 3-piece lens)
• Most successful IOLs today
•...
HYDROPHILIC ACRYLIC
• Mixture of hydroxyethylmethacrylate (poly- HEMA) and hydrophilic
acrylic monomer
• End of the 1980s
...
HYDROGEL
• Swell in water
• 18% to 38% water content
• Copolymers of methacrylate esters
• Hydrophilic comonomer with a hy...
COLLAMER
• STAAR Surgical
• Hydrophilic
• p-HEMA with 33% water and 0.2% porcine
collagen with a benzophenone UV blocker
UV ABSORPTION
• Additive
• Chemical bonding
– Hydroxybenzophenones
– Hydroxyphenylbenzotriazoles
• UV-absorbing chromophor...
LENS CHEMISTRY
(Haptic Material)
• PMMA
• Polyimide (Elastimide)
• Polyvinylidene fluoride (PVDF)
– good material memory
ASPHERIC IOLS
ASPHERIC IOLs
• Human eye : Aspheric Optics
• Cornea : Positive spherical
aberration
• Young crystalline lens :
Negative s...
Conventional IOL increase
the spherical aberration of the eye
HOW TO OVERCOME ?
• Strategy 1:
– Lens with negative spherical aberrations to
balance the normally positive corneal spheri...
• Anterior prolate surface
– Tecnis, Advanced Medical Optics (AMO)
• Posterior prolate surface
– Acrysof IQ, Alcon Laborat...
ASPHERIC IOLs
• Need perfect centration
– Decentered IOLs can induce
coma
• Decreased depth
perception
• More expensive
• ...
PREMIUM IOLs
• MULTIFOCAL
• ACCOMODATIVE
• TORIC IOLs
RESTORATION OF ACCOMMODATION IN PSEUDOPHAKIA
METHODS
MonovisionMultifocal IOL Accommodative
IOL
MULTIFOCAL IOLs
• Single IOL with two or more focal points
• Types
– Refractive
– Diffractive
– Combination of both
• Hoffer in 1982
• Patient with 6/6 vision in spite of an IOL that
was decentred by more than 50% of the
pupillary area
• ...
REFRACTIVE MULTIFOCAL IOLs
• Bull’s eye lens
– Concentric rings of different
powers
– Central addition surrounded by
dista...
12345
Bright light/ Distance dominant zone
Large Near dominant zone
Low light/ Distance
dominant zone
Distance zone
Near z...
• Silicone MIOLs
– Array multifocal IOL (AMO)
– First FDA approved foldable MIOL
• 5 concentric zones on its anterior surf...
Multiple focal points of a refractive multifocal IOL
DIFFRACTIVE MULTIFOCAL IOLs
• Anterior aspheric surface : basic
refractive power
• Multiple grooves on posterior
surface :...
DIFFRACTIVE MULTIFOCAL IOLs
Multiple focal points of a diffractive multifocal IOL
Based on the average
corneal-surface
wavefront-derived
spherical aberration
• Tecnis Multifocal IOLs (AMO)
– ZM900 (Silicone)
– ZA00 (Acrylic)
• Optic Diameter 6.0 mm
• Optic Type
– Modified prolate...
• Acrysof IQ ReSTOR (Alcon)
– Acrylic diffractive multifocal IOL with apodized design
– Optic diameter- 6 mm
– Refractive ...
Apodization literally means "removing the foot“
To remove or smooth a discontinuity at the edges
• Refractive lenses (pupil
dependent) ideal for
– Light to moderate readers
– Drive mostly during the day.
– Play sports,
...
PATIENT SELECTION FOR MfIOLs
(most important factor)
• Strong desire to be spectacle independent
• Functional & occupation...
INTRAOPERATIVE EXCLUSION
• Significant vitreous loss during surgery
• Pupil trauma during surgery
• Zonular damage
• Capsu...
SPECIAL CONSIDERATIONS FOR MfIOLS
• Counselling (most important)
• Accurate Biometry
– IOL master strongly recommended
– i...
MIXING AND MATCHING MULTIFOCAL IOLs
Stefan Pieh, MD; Herbert Weghaupt, Christian Skorpik MD; Contrast Sensitivity
and glar...
• Loss of contrast sensitivity
• Glare and halos
– scattering of light at the dividing line of the different
zones
– impro...
ACCOMMODATIVE IOLs
• Monofocal IOL
• Changes position inside the eye as the eye's
focusing muscle contracts
• 1 mm of ante...
• Silicone
– Crystalens (Bausch & Lomb)
– Only FDA approved IOL for correction of
presbyopia
• Hydrophilic Acrylic
– BioCo...
Akkolens IOL (Akkolens,
Lumina IOL)
• Principle of the Alvarez lens
– Two sinusoidal optical surfaces slide across one ano...
Synchrony Dual-Optic IOL (Visiogen)
• One piece Silicon foldable IOL
• Two optics
– high plus anterior
– posterior minus l...
TORIC IOLs
• 22% of patients undergoing cataract surgery
have substantial corneal astigmatism
• >1.25 D
• Staar Surgical Intraocular Lens
– First FDA approved (in 1998) toric IOL
– 2.00 and 3.50D
– Plate-haptic
– Poor rotation...
• AcrySof IQ Toric IOL (Alcon Labs, USA)
– September 2005
– T3 to T9
– posterior surface has added cylindrical power and a...
• CANDIDATES
– > or = 1.0D regular corneal astigmatism
• AcrySof Toric IOL Calculator
– compensates for surgically induced astigmatism
• Marking The Eye
– reference marks at the 3- and 9-o’clock
– sitting upright
• Aligning the Toric IOL with the Axis
– Gro...
• 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
ROLLABLE IOLs
• Ultrathin ~100 µ
• Hydrophilic material
• Front surface curved
• Back surface: series of steps with concen...
IOL IMPLANTAION IN SPECIAL SITUATIONS
• ABSENCE OF CAPSULAR SUPPORT
– Scleral fixation (suture/glue)
– Iris fixated
– ACIO...
ANIRIDIA IOLs
• Various designs
– Overall size = 12.5 to 14 mm
– Optic diameter = 3.5 to 5 mm
– Central clear optic
– Surr...
PHAKIC IOLs
PHAKIC IOLs
• Implantation of IOL without removing natural
crystalline lens.
• ADVANTAGE: Preserves natural
accommodation
...
PHAKIC IOLs
• Posterior Chamber
• Iris fixated
• Angle fixated
PHAKIC IOLs
• Implantable collamer lens (ICL) (VISIAN; STAAR)
• Phakic refractive lens (Mellennium)
• Sticklens
• COMPLICATIONS:
– End...
Implantable Collamer Lens (ICL)
• Pre-crystalline lens made of silicone or
collamer.
• Length of the lens = white-to-white...
• COMPLICATIONS:
– Constant contact pressure
– Cataract
– Ciliary body reactions
– Prevent free passage of aqueous.- Iride...
IRIS FIXATED PHAKIC IOL
• VERISYSE/ARTISAN (AMO/OPTECH)
– Made of PMMA
– convexo-concave
– Length = 7.2 – 8.5 mm
– Optic s...
IRIS FIXATED PHAKIC IOL
• ADVANTAGES OVER ICL:
– Customized smaller size possible
– Easier examination from end-to-end
• C...
ANGLE FIXATED PHAKIC IOL
• TWO TYPES –
– 4 point fixation
• Baikoff’s modification of Kelman type haptic design
• NuVita M...
ANGLE FIXATED PHAKIC IOL
• COMPLICATIONS –
– Endothelial cell loss
– Irregular pupil
– Iris depigmentation
– Post-op infla...
PIGGYBACK IOLs
• An intraocular lens that
“piggybacks” onto an existing
intraocular lens or two IOLs are
implanted simulta...
• Easier to place 2nd IOL than to explant IOL &
replace it
– Lesser risk
– More predictable
– Can change power with time-b...
• COMPLICATIONS
– Interlenticular opacification
• (Interpseudophakos Elshnig’s pearls)
• (RED ROCK SYNDROME)
– Unpredictab...
COMPLICATIONS RELATED TO IOLs
• MALPOSITIONS
– Pupil capture
– Decentration
– Windshield wiper syndrome
– Sunset syndrome
...
• IOL material : acrylic > silicone
• Refractive index : negative dysphotopsia more
with higher refractive indices
• Small...
RECENT ADVANCES AND THE FUTURE
• LIGHT ADJUSTABLE IOL
• TELESCOPIC IOLs
• SMART IOLs
• ELECTRONIC IOLs
LIGHT ADJUSTABLE IOL
• Calhoun Vision
• Silicone lens with two C-PMMA haptics
• Photosensitive to the near-ultraviolet wav...
• Sunglasses for about three weeks
IMPLANTABLE MINIATURE TELESCOPE
• Miniature implantable Galiliean telescope
– Implanted in posterior chamber
– Held in pos...
• Telephoto system : 2-3 times magnification
• Images in the central visual field
– not be focused directly on the damaged...
• DRAWBACKS:
– Surgically more challenging
– Difficulty due to the size and
weight of the implant
– Endothelial compromise...
TELESCOPIC IOL
• Next generation of implantable miniature telescopes.
• Uses mirrors rather than glass lenses
• 25 X magni...
SMART IOL
IOL POWER CALCULATIONS
• Before 1980s,
– Best described as ‘educated guesses’
• The IDEM lens (ideal emmetropia lens)
– +1...
IOL POWER PREDICTION FORMULAE
• First Generation - SRK- 1 and Binkhorst formulae
• Second Generation – SRK-2
• Third Gener...
• Theoretical formulae
• Regression formulae
• human eye functions as a
dual lens system
• position of the cornea
and the retina is fixed
• effective IOL power
– Power...
THE ELPo
• Dr. Jack Holladay
• Anatomical factors
– axial length
– steepness of the cornea
– limbal white to white measure...
• IOL and surgery related factors
– anterior angulation
– material of the haptic
– material of the optic
– Asphericity
• I...
MANUFACTURER’S LENS CONSTANT
• axial length of 23.5mm (applanation A scans)
• central corneal power 43.86D (manual
keratom...
• The SRK formula
– IOL power = A – 2.5 L – 0.9 K.
– Donald Sanders, John Retzlaff and Kraff
– mid 1980’s.
– 6835 eyes
– 2...
• SRK 2 formula
– Axial length 21-22mm, add 1 to A
– 20-21 add 2
– < 20 add 3
– Over 24.5mm subtract 0.5
• SRK T Formula
– third generation formula
– 1990
– John Retzlaff and Donald Sanders
– combines theoretical and regression...
• The Hoffer-Q formula
– Dr. Kenneth Hoffer in 1993
– P = f (A, K, Rx, pACD)
– short eye balls
• HAIGIS Formula
– also called the
GOW 70 formula
– Gernet, Ostholt
and Werner in
1970
• three ‘A constants’
– a0 : manufacturers lens constant
– a1 : pre operative ultrasonically measured ant
chamber depth (t...
• Holladay 2
– 1998
– Accurate estimation of the ELPo
• Axial length.
• Central corneal power (K)
• Anterior chamber depth...
• Nine types’ of eyes model
• available as part of a package called the
‘Holladay IOL consultant
• entire range of axial lengths
IOL injectors
• Preloaded
• Easy loading
• Basic type
• Autosert (alcon)
MANUFACTURING PROCESS
• MOLDING
• LATHE CUT
• TUMBLE POLISH
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Intraocular lenses

Everything you need to know about IOLs

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Intraocular lenses

  1. 1. INTRAOCULAR LENSES
  2. 2. OVERVIEW • HISTORICAL ASPECTS • PRESENT DAY IOLs – Classification – Design – Material • ASPHERIC IOLs • MULTIFOCAL, ACCOMODATIVE, TORIC IOLs • PHAKIC IOLs • IOL IMPLANTATION IN SPECIAL SITUATIONS • COMPLICATIONS RELATED TO IOLs • RECENT ADVANCES AND THE FUTURE • IOL POWER CALCULATIONs • MANUFACTURING PROCESS
  3. 3. HISTORICAL ASPECTS
  4. 4. The Evolution of Intraocular Lenses* *Yanoff & Duker: Ophthalmology, 3rd ed. Table 5-2-1, pg 394
  5. 5. HISTORY • First IOL implantation – Sir Harold Ridley • November 29, 1949 at St. Thomas Hospital, London • 49 year woman • ECCE with in-the-bag placement • Biconvex perspex (Transpex 1) disc; 138 mg • Rayners Optical Company, Brighton • Substantial post op myopia (-24.0 Ds/ +6.0 Dcyl X 30 degrees) • IOL exchange in February, 1950 • Revealed only in 1951 at the Oxford Ophthalmic Congress 8.5 mm diameter, 2.4 mm thick, 108 mg In 1795, Casamata implanted glass IOL which sank posteriorly.
  6. 6. – 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 *Ridley H: Intraocular acrylic lenses—past, present and future. Trans Ophthalmol Soc UK 1964;84:5–14
  7. 7. EARLY ANTERIOR CHAMBER IOLs • Rigid or semirigid AC-IOL – Baron, in France; May 13, 1952 – Scharf and Strampelli • Flexible or semiflexible AC-IOL – Open haptic loops – Closed haptic loops – Peter Choyce • Mark I to Mark VII Strampelli Tripod AC-IOL (1953) Choyce Mark I AC-IOL(1956) Dannheim AC-IOL with closed haptics (1952) Ridley Tripod AC-IOL (1957–60)
  8. 8. – Barraquer • Open-loop AC-IOL with J-haptics • Nylon haptics – Complications • High vaulting – Late endothelial atrophy, – Corneal decompensation, – Pseudophakic bullous keratopathy • Uveal erosion – Uveitis-glaucoma-hyphema (UGH) syndrome
  9. 9. ADVANTAGES • Less decenteration • Decreased reaction DISADVANTAGES • Corneal decompensation • Pseudophakic Bullous keratopathy • Uveitis • Secondary glaucoma • UGH syndrome
  10. 10. IRIS-SUPPORTED LENSES • Epstein, 1953 – Collar stud lens – Maltese cross lens – Copeland lens • Iris pigment epithelial defects/atrophy, • Pigment dispersion glaucoma • Corneal complications
  11. 11. • Cornelius Binkhorst, – Iris clip lens; four-loop (1957) – Iridocapsular fixation; two loop (1965) • Forerunner to capsular sac (in-the-bag) fixation of modern posterior chamber IOLs • Fyodorov modification (1966) – Fyodorov I – Fyodorov II (Sputnik) – Three haptics in front and three behind the iris
  12. 12. • Jan Worst (Holland) • Medallion IOL, mid-1970s – Eliminating the anterior haptics while retaining the horizontally oriented posterior ones – Prolene suture through the superior optic, securing it to the iris – Hydrolytic biodegradation of the nylon stitches Binkhorst 4-loop lens (1957/58), Fyodorov iris clip Sputnik lens (1968), Binkhorst 2-loop lens for iridocapsular fixation (1965).
  13. 13. • Iris claw lens (lobster claw); by Worst in 1978 – Artisan/Artiflex Lens – Slits in both haptics – Clamped into the mid-periphery
  14. 14. 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
  15. 15. INTERMEDIATE ACIOLs • Improved manufacturing techniques – Tumble polishing of IOLs • Flexible loops with multiple point of fixation • More stable • Anterior-posterior vaulting characteristics • Elimination of sharp optic or haptic edges • Fixation elements – Spatula-like footplates – Small-diameter lens loops • Closed • Open
  16. 16. 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 (various manufacturers). Azar 91Z AC-IOL (1982) ORC Inc Stableflex AC-IOL (1983) Surgidev Inc Style 10 Leiske ACIOL (1978) Mark VIII, Mark IX, flexible ACIOL, Kelman, Kelman flexible tripod, Kelman quadraflex, Kelman multiplex 4 point fixation
  17. 17. • PHACOEMULSIFICATION • SOPHISTICATED MICROSURGERY • OPHTHALMIC VISCO-SURGICAL DEVICES • CONTINUOUS CURVILINEAR CAPSULORRHEXIS – allows copious hydrodissection – stability of the capsular bag • HYDRODISSECTION • 1981 : FDA approval for IOL implantation following cataract surgery IMPROVED PCIOLs Charles Kelman
  18. 18. • Rigid tripod design (John Pearce) • J-looped PCIOL (Steven Shearing) • Modified J-looped PCIOL (Sinskey) • C-looped PCIOL (Simcoe) • One piece PCIOL (Eric Arnott)
  19. 19. ADVANTAGES OF IN-THE-BAG PLACEMENT • Proper anatomical site • Symmetrical loop placement • 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 • Loop material alteration is less likely • Safer for children and young individuals • Reduced posterior capsular opacification
  20. 20. MODERN IOLs
  21. 21. PRESENT DAY IOLs • Classification • Design • Material
  22. 22. CLASSIFICATION
  23. 23. INTRAOCULAR LENS DESIGN • Single piece / monobloc • Plate haptic / open loop haptics • Angulated / planar haptics • Edge design • Optic design
  24. 24. ANGULATED HAPTICS ALLOW FOR ADEQUATE PUPILLARY CLEARANCE AND ADHESION TO THE POSTERIOR CAPSULE
  25. 25. • Square, truncated optic edge
  26. 26. HAPTIC DESIGN • Plate haptic • Loop haptic – C-loop – J-loop – Modifies C-loop • Plate-loop
  27. 27. LENS CHEMISTRY (Optic Materials) • RIGID MATERIALS – PMMA (Polymethylmethacrylate) – Water content <1% – Refractive index 1.49 – Usually single piece – May be penetrated by aqueous humor known as ‘glistenings’ (very rare) • FLEXIBLE MATERIALS – Silicones – Acrylics • Hydrophilic • Hydrophobic – Hydrogels – Collamer
  28. 28. FLEXIBLE MATERIALS • Silicone – Polymers of silicone and oxygen – Since 1984; first material for foldable IOLs – Hydrophobic (contact angle with water of 99°) – 1.41 to 1.46 – 3 piece – Thick optics (need larger incisons) – Handling is difficult; loading into injector – Bacterial adhesion – Anterior capsule rim opacifies quickly – Low PCO – Lowest threshold for YAG laser damage – Glistenings – Adherence of silicone droplets
  29. 29. HYDROPHOBIC ACRYLIC • Copolymers of acrylate and methacrylate • 1993 (Acrysof 3-piece lens) • Most successful IOLs today • Angle of contact with water is 73° • 3-piece or 1-piece designs • 1.44 to 1.55 • Easy handling; prone to mechanical damage • At least a 2.2-mm incision • Low PCO rates • Good resistance to YAG laser • Photopsias • Glistenings • BSS packaging (reach 4% water content before implantation)
  30. 30. HYDROPHILIC ACRYLIC • Mixture of hydroxyethylmethacrylate (poly- HEMA) and hydrophilic acrylic monomer • End of the 1980s • 1.43 • 18 -26% water content • Contact angle with water is lower than 50° • Single piece • Easiest to handle; less mechanical/YAG laser damage • Sub-2-mm incisions • Higher PCO rate • Low resistance to capsular contraction • Calcium deposits
  31. 31. HYDROGEL • Swell in water • 18% to 38% water content • Copolymers of methacrylate esters • Hydrophilic comonomer with a hydroxyl functional group such as HEMA
  32. 32. COLLAMER • STAAR Surgical • Hydrophilic • p-HEMA with 33% water and 0.2% porcine collagen with a benzophenone UV blocker
  33. 33. UV ABSORPTION • Additive • Chemical bonding – Hydroxybenzophenones – Hydroxyphenylbenzotriazoles • UV-absorbing chromophore – Protective to macula – Interference with melatonin cycle
  34. 34. LENS CHEMISTRY (Haptic Material) • PMMA • Polyimide (Elastimide) • Polyvinylidene fluoride (PVDF) – good material memory
  35. 35. ASPHERIC IOLS
  36. 36. ASPHERIC IOLs • Human eye : Aspheric Optics • Cornea : Positive spherical aberration • Young crystalline lens : Negative spherical aberration • Ageing crystalline lens : Increased positive spherical aberration • spherical aberration ~ fourth power of the pupil diameter
  37. 37. Conventional IOL increase the spherical aberration of the eye
  38. 38. 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
  39. 39. • 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
  40. 40. ASPHERIC IOLs • Need perfect centration – Decentered IOLs can induce coma • 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 patients had an average increase of 130+ feet (vs the control lens) in which to stop after identifying a warning sign • Better option for younger patients
  41. 41. PREMIUM IOLs • MULTIFOCAL • ACCOMODATIVE • TORIC IOLs
  42. 42. RESTORATION OF ACCOMMODATION IN PSEUDOPHAKIA METHODS MonovisionMultifocal IOL Accommodative IOL
  43. 43. MULTIFOCAL IOLs • Single IOL with two or more focal points • Types – Refractive – Diffractive – Combination of both
  44. 44. • Hoffer in 1982 • Patient with 6/6 vision in spite of an IOL that was decentred by more than 50% of the pupillary area • Dr. John Pearce, 1986; bull’s eye style • Pupil dependent
  45. 45. 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
  46. 46. 12345 Bright light/ Distance dominant zone Large Near dominant zone Low light/ Distance dominant zone Distance zone Near zone Aspheric transition REFRACTIVE MULTIFOCAL IOLs
  47. 47. • Silicone MIOLs – Array multifocal IOL (AMO) – First FDA approved foldable MIOL • 5 concentric zones on its anterior surface • 50% distance, 37% near, 15% for intermediate vision • Acrylic MIOLs – ReZoom multifocal IOL (AMO) • Zone 1,3 and 5 : distance • Zone 2 and 4 : near • 60% distance, 40% near and intermediate • PREZIOL (Acrylic)(Care Group) – Manufactured by Indian company – Also available as non foldable PMMA lens
  48. 48. Multiple focal points of a refractive multifocal IOL
  49. 49. DIFFRACTIVE MULTIFOCAL IOLs • Anterior aspheric surface : basic refractive power • Multiple grooves on posterior surface : diffractive power • 41% of light : distance • 41% : near vision • PMMA – 3M corp (3M diffractive MIOL) – Pharmacia 808,811E • Pupil independent
  50. 50. DIFFRACTIVE MULTIFOCAL IOLs
  51. 51. Multiple focal points of a diffractive multifocal IOL
  52. 52. Based on the average corneal-surface wavefront-derived spherical aberration
  53. 53. • Tecnis Multifocal IOLs (AMO) – ZM900 (Silicone) – ZA00 (Acrylic) • Optic Diameter 6.0 mm • Optic Type – Modified prolate anterior surface – Total diffractive posterior surface – Diffractive Power +4.0 diopters of near addition (+3.0 Diopters at spectacle plane)
  54. 54. • 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)
  55. 55. Apodization literally means "removing the foot“ To remove or smooth a discontinuity at the edges
  56. 56. • 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 • Movies • Night time driving
  57. 57. 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
  58. 58. INTRAOPERATIVE EXCLUSION • Significant vitreous loss during surgery • Pupil trauma during surgery • Zonular damage • Capsulorhexis tear • Capsular rupture • Eccentric CCC
  59. 59. SPECIAL CONSIDERATIONS FOR MfIOLS • Counselling (most important) • Accurate Biometry – IOL master strongly recommended – immersion biometry better than applanation biometry • Power Calculation – Plano to <+0.25 – newer formulae • Surgical Technique – Round, centered CCC completely overlapping the lens optic – Removal of all viscoelastic from behind the lens
  60. 60. MIXING AND MATCHING MULTIFOCAL IOLs Stefan Pieh, MD; Herbert Weghaupt, Christian Skorpik MD; Contrast Sensitivity and glare disability with diffractive and refractive multifocal IOL. J Cataract and Refract Surgery 1998; 24-659-662.
  61. 61. • 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 Visual-Cortical Neuro-adaptation
  62. 62. 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
  63. 63. • Silicone – Crystalens (Bausch & Lomb) – Only FDA approved IOL for correction of presbyopia • Hydrophilic Acrylic – BioComFold type 43E (Morcher GmbH) – 1CU (HumanOptics AG) – Tetraflex (Lenstec Inc.)
  64. 64. Akkolens IOL (Akkolens, Lumina IOL) • Principle of the Alvarez lens – Two sinusoidal optical surfaces slide across one another along the horizontal axis • Anterior element with a spherical lens • Two cubic optical surfaces for varifocal effect – fitted by spring-like haptics fused at the rim – movement perpendicular to the optical axis • Implanted in the sulcus • 2 D to 5 D of near add power
  65. 65. Synchrony Dual-Optic IOL (Visiogen) • One piece Silicon foldable IOL • Two optics – high plus anterior – posterior minus lens • connected by spring like haptics. • Zonular tension is released – compression of optic-spring haptic releases anterior optic forward.
  66. 66. TORIC IOLs • 22% of patients undergoing cataract surgery have substantial corneal astigmatism • >1.25 D
  67. 67. • Staar Surgical Intraocular Lens – First FDA approved (in 1998) toric IOL – 2.00 and 3.50D – Plate-haptic – Poor rotational stability – limited power range
  68. 68. • AcrySof IQ Toric IOL (Alcon Labs, USA) – September 2005 – T3 to T9 – posterior surface has added cylindrical power and axis markings • Acri.Comfort 646TLC and Acri.LISA toric 466TD – Carl Zeiss Meditec – incision < 2 mm • Rayner Sulcoflex toric 653T (Piggy back sulcus lens)
  69. 69. • CANDIDATES – > or = 1.0D regular corneal astigmatism
  70. 70. • AcrySof Toric IOL Calculator – compensates for surgically induced astigmatism
  71. 71. • Marking The Eye – reference marks at the 3- and 9-o’clock – sitting upright • Aligning the Toric IOL with the Axis – Gross alignment, – Viscoelastic removal, – Final alignment
  72. 72. • Remove OVD from behind the IOL
  73. 73. • For every 1 degree of axis rotation, 3.3% of the lens cylinder power may be lost. • At 30 degrees, all effect is lost
  74. 74. ROLLABLE IOLs • Ultrathin ~100 µ • Hydrophilic material • Front surface curved • Back surface: series of steps with concentric rings • Open up gradually • Implanted by phakonit technique • Acrismart • Thin Optx ultrachoice • Slimflex lens
  75. 75. IOL IMPLANTAION IN SPECIAL SITUATIONS • ABSENCE OF CAPSULAR SUPPORT – Scleral fixation (suture/glue) – Iris fixated – ACIOLs • PEDIATRIC AGE GROUP – Heparin coated – Multifocal IOLs • DRUG ELUTING IOLs – Triamcinolone acetonide – Dexamethsone – Antibiotic – Diclofenac sodium (0.2 mg/mL) – Mitomicin C (0.2 mg/mL) – Colchicine (12.5 mg/mL) and 5-fluorouracile (10 mg/ml) – Anti-VEGF
  76. 76. ANIRIDIA IOLs • Various designs – Overall size = 12.5 to 14 mm – Optic diameter = 3.5 to 5 mm – Central clear optic – Surrounding colored diaphragm
  77. 77. PHAKIC IOLs
  78. 78. 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.
  79. 79. PHAKIC IOLs • Posterior Chamber • Iris fixated • Angle fixated PHAKIC IOLs
  80. 80. • Implantable collamer lens (ICL) (VISIAN; STAAR) • Phakic refractive lens (Mellennium) • Sticklens • COMPLICATIONS: – Endothelial cell damage – Inflammation – Pigment dispersal – Elevated IOP – Cataract
  81. 81. Implantable Collamer Lens (ICL) • Pre-crystalline lens made of silicone or collamer. • Length of the lens = white-to-white limbal diameter - 0.5 mm – Overall size- 11-13 mm – Otical zone - 4.5-5.5 mm – Toric model also available
  82. 82. • COMPLICATIONS: – Constant contact pressure – Cataract – Ciliary body reactions – Prevent free passage of aqueous.- Iridectomy required – SPINNAKER EFFECT: Blowing sail of a boat
  83. 83. IRIS FIXATED PHAKIC IOL • VERISYSE/ARTISAN (AMO/OPTECH) – Made of PMMA – convexo-concave – Length = 7.2 – 8.5 mm – Optic size = 5-6 mm – Haptics fixed to iris –claws
  84. 84. IRIS FIXATED PHAKIC IOL • 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
  85. 85. ANGLE FIXATED PHAKIC IOL • TWO TYPES – – 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
  86. 86. ANGLE FIXATED PHAKIC IOL • COMPLICATIONS – – Endothelial cell loss – Irregular pupil – Iris depigmentation – Post-op inflammation – Halos and glare – Surgical induced astigmatism
  87. 87. PIGGYBACK IOLs • An intraocular lens that “piggybacks” onto an existing intraocular lens or two IOLs are implanted simultaneously. • First IOL is placed in the capsular bag. • The second (piggyback) IOL is placed in the bag or sulcus.
  88. 88. • Easier to place 2nd IOL than to explant IOL & replace it – Lesser risk – More predictable – Can change power with time-by adding IOL or explanting an IOL – Better image quality – Increased depth of focus
  89. 89. • COMPLICATIONS – Interlenticular opacification • (Interpseudophakos Elshnig’s pearls) • (RED ROCK SYNDROME) – Unpredictable final IOL position
  90. 90. 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
  91. 91. • IOL material : acrylic > silicone • Refractive index : negative dysphotopsia more with higher refractive indices • Smaller optic size • Square edge • Multifocal IOL • Iris-optic distance • Self resolving in a few weeks (cortical adaptation)
  92. 92. RECENT ADVANCES AND THE FUTURE • LIGHT ADJUSTABLE IOL • TELESCOPIC IOLs • SMART IOLs • ELECTRONIC IOLs
  93. 93. LIGHT ADJUSTABLE IOL • Calhoun Vision • Silicone lens with two C-PMMA haptics • Photosensitive to the near-ultraviolet wavelength of energy in a specific pattern – myopic adjustment : periphery of the lens • Final irradiation step locks in the power change • ±2 D for sphere and 2.5 D for astigmatism at the spectacle plane
  94. 94. • Sunglasses for about three weeks
  95. 95. IMPLANTABLE MINIATURE TELESCOPE • 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.
  96. 96. • Telephoto system : 2-3 times magnification • Images in the central visual field – not be focused directly on the damaged macula – over other healthy areas of the central and peripheral retina
  97. 97. • 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
  98. 98. TELESCOPIC IOL • Next generation of implantable miniature telescopes. • Uses mirrors rather than glass lenses • 25 X magnification of central images • The LMI (Lipshitz Macular Implant) – optics is 6.5mm – slightly thicker than a standard IOL • Contains 2 miniature mirrors – 2.8 mm posterior doughnut shaped mirror that reflects light anteriorly – 1.4 mm central retina–facing mirror which in turn focuses the light on retina). • Does not affect peripheral vision.
  99. 99. SMART IOL
  100. 100. IOL POWER CALCULATIONS • Before 1980s, – Best described as ‘educated guesses’ • The IDEM lens (ideal emmetropia lens) – +17.0 D for an AC lens, – +19.0D for an iris fixated lens – +21.0D for a posterior chamber lens • The Standard lens – +1.25D added to the IDEM lens power • The Emmetropia lens – (pre existing refractive error) X 1.25 + IDEM lens power
  101. 101. IOL POWER PREDICTION FORMULAE • First Generation - SRK- 1 and Binkhorst formulae • Second Generation – SRK-2 • Third Generation – SRK T, Hollday. Hoffer-Q • Fourth Generation – Hollday 2, HAIGIS
  102. 102. • Theoretical formulae • Regression formulae
  103. 103. • human eye functions as a dual lens system • position of the cornea and the retina is fixed • effective IOL power – Power of iol – Postion • “in the bag” IOL is 21.0D • in the sulcus will function as a 22.0 lens
  104. 104. THE ELPo • Dr. Jack Holladay • Anatomical factors – axial length – steepness of the cornea – limbal white to white measurements – preoperative – anterior chamber depth – lens thickness • position of the capsular bag equator from the corneal vertex : pre op ACD and 40% of the crystalline lens thickness
  105. 105. • IOL and surgery related factors – anterior angulation – material of the haptic – material of the optic – Asphericity • Individual Surgeon’s Technique – CCC size and centration – inadequate removal of visco-elastic from behind the IOL – Bag to Sulcus shift
  106. 106. MANUFACTURER’S LENS CONSTANT • axial length of 23.5mm (applanation A scans) • central corneal power 43.86D (manual keratometry) • limbal white to white diameter of 11.7mm • 22.0mm – 26.0mm • central corneal power of 41.0D – 46.0D
  107. 107. • The SRK formula – IOL power = A – 2.5 L – 0.9 K. – Donald Sanders, John Retzlaff and Kraff – mid 1980’s. – 6835 eyes – 22.0m – 24.5mm
  108. 108. • SRK 2 formula – Axial length 21-22mm, add 1 to A – 20-21 add 2 – < 20 add 3 – Over 24.5mm subtract 0.5
  109. 109. • SRK T Formula – third generation formula – 1990 – John Retzlaff and Donald Sanders – combines theoretical and regression formulae – predicted post operative anterior chamber depth – retinal thickness – refractive indices of the cornea – regression element is used to optimize the ‘A constant
  110. 110. • The Hoffer-Q formula – Dr. Kenneth Hoffer in 1993 – P = f (A, K, Rx, pACD) – short eye balls
  111. 111. • HAIGIS Formula – also called the GOW 70 formula – Gernet, Ostholt and Werner in 1970
  112. 112. • three ‘A constants’ – a0 : manufacturers lens constant – a1 : pre operative ultrasonically measured ant chamber depth (this has a default value of 0.4) – a2 axial length measurements (default value of 0.1) – enables customizationof each component – entire range of axial length values
  113. 113. • Holladay 2 – 1998 – Accurate estimation of the ELPo • Axial length. • Central corneal power (K) • Anterior chamber depth • Lens thickness measurement • Limbal white to white measurement • Age of the patient • Previous refraction of the patient
  114. 114. • Nine types’ of eyes model
  115. 115. • available as part of a package called the ‘Holladay IOL consultant • entire range of axial lengths
  116. 116. IOL injectors • Preloaded • Easy loading • Basic type • Autosert (alcon)
  117. 117. MANUFACTURING PROCESS • MOLDING • LATHE CUT • TUMBLE POLISH
  118. 118. THANK YOU

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