Everything you need to know about IOLs

1. INTRAOCULAR LENSES

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. HISTORICAL ASPECTS

4. The Evolution of Intraocular Lenses*
*Yanoff & Duker: Ophthalmology, 3rd ed. Table 5-2-1, pg 394

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. – 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. 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. – 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. ADVANTAGES
• Less decenteration
• Decreased reaction
DISADVANTAGES
• Corneal decompensation
• Pseudophakic Bullous
keratopathy
• Uveitis
• Secondary glaucoma
• UGH syndrome

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. • 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. • 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. • Iris claw lens (lobster claw); by Worst in 1978
– Artisan/Artiflex Lens
– Slits in both haptics
– Clamped into the mid-periphery

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. 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. 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. • 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. • Rigid tripod design (John Pearce)
• J-looped PCIOL (Steven Shearing)
• Modified J-looped PCIOL (Sinskey)
• C-looped PCIOL (Simcoe)
• One piece PCIOL (Eric Arnott)

21. 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

22. MODERN IOLs

23. PRESENT DAY IOLs
• Classification
• Design
• Material

24. CLASSIFICATION

25. INTRAOCULAR LENS DESIGN
• Single piece / monobloc
• Plate haptic / open loop haptics
• Angulated / planar haptics
• Edge design
• Optic design

27. ANGULATED HAPTICS ALLOW FOR ADEQUATE PUPILLARY
CLEARANCE AND ADHESION TO THE POSTERIOR CAPSULE

28. • Square, truncated optic edge

30. HAPTIC DESIGN
• Plate haptic
• Loop haptic
– C-loop
– J-loop
– Modifies C-loop
• Plate-loop

31. 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

32. 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

33. 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)

34. 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

35. HYDROGEL
• Swell in water
• 18% to 38% water content
• Copolymers of methacrylate esters
• Hydrophilic comonomer with a hydroxyl
functional group such as HEMA

36. COLLAMER
• STAAR Surgical
• Hydrophilic
• p-HEMA with 33% water and 0.2% porcine
collagen with a benzophenone UV blocker

37. UV ABSORPTION
• Additive
• Chemical bonding
– Hydroxybenzophenones
– Hydroxyphenylbenzotriazoles
• UV-absorbing chromophore
– Protective to macula
– Interference with melatonin cycle

38. LENS CHEMISTRY
(Haptic Material)
• PMMA
• Polyimide (Elastimide)
• Polyvinylidene fluoride (PVDF)
– good material memory

39. ASPHERIC IOLS

40. 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

42. Conventional IOL increase
the spherical aberration of the eye

43. 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

45. • 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

47. 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

48. PREMIUM IOLs
• MULTIFOCAL
• ACCOMODATIVE
• TORIC IOLs

49. RESTORATION OF ACCOMMODATION IN PSEUDOPHAKIA
METHODS
MonovisionMultifocal IOL Accommodative
IOL

50. MULTIFOCAL IOLs
• Single IOL with two or more focal points
• Types
– Refractive
– Diffractive
– Combination of both

51. • 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

52. 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

53. 12345
Bright light/ Distance dominant zone
Large Near dominant zone
Low light/ Distance
dominant zone
Distance zone
Near zone Aspheric transition
REFRACTIVE MULTIFOCAL IOLs

54. • 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

55. Multiple focal points of a refractive multifocal IOL

56. 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

57. DIFFRACTIVE MULTIFOCAL IOLs

58. Multiple focal points of a diffractive multifocal IOL

59. Based on the average
corneal-surface
wavefront-derived
spherical aberration

60. • 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)

61. • 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)

62. Apodization literally means "removing the foot“
To remove or smooth a discontinuity at the edges

63. • 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

64. 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

65. INTRAOPERATIVE EXCLUSION
• Significant vitreous loss during surgery
• Pupil trauma during surgery
• Zonular damage
• Capsulorhexis tear
• Capsular rupture
• Eccentric CCC

66. 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

67. 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.

68. • 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

69. 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

70. • 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.)

72. 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

74. 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.

76. TORIC IOLs
• 22% of patients undergoing cataract surgery
have substantial corneal astigmatism
• >1.25 D

77. • Staar Surgical Intraocular Lens
– First FDA approved (in 1998) toric IOL
– 2.00 and 3.50D
– Plate-haptic
– Poor rotational stability
– limited power range

78. • 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)

79. • CANDIDATES
– > or = 1.0D regular corneal astigmatism

80. • AcrySof Toric IOL Calculator
– compensates for surgically induced astigmatism

81. • 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

82. • Remove OVD
from behind the
IOL

83. • For every 1 degree of axis rotation, 3.3% of
the lens cylinder power may be lost.
• At 30 degrees, all effect is lost

84. 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

85. 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

86. ANIRIDIA IOLs
• Various designs
– Overall size = 12.5 to 14 mm
– Optic diameter = 3.5 to 5 mm
– Central clear optic
– Surrounding colored diaphragm

87. PHAKIC IOLs

88. 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.

89. PHAKIC IOLs
• Posterior Chamber
• Iris fixated
• Angle fixated
PHAKIC IOLs

90. • Implantable collamer lens (ICL) (VISIAN; STAAR)
• Phakic refractive lens (Mellennium)
• Sticklens
• COMPLICATIONS:
– Endothelial cell damage
– Inflammation
– Pigment dispersal
– Elevated IOP
– Cataract

91. 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

92. • COMPLICATIONS:
– Constant contact pressure
– Cataract
– Ciliary body reactions
– Prevent free passage of aqueous.- Iridectomy
required
– SPINNAKER EFFECT: Blowing sail of a boat

93. 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

94. 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

95. 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

96. ANGLE FIXATED PHAKIC IOL
• COMPLICATIONS –
– Endothelial cell loss
– Irregular pupil
– Iris depigmentation
– Post-op inflammation
– Halos and glare
– Surgical induced astigmatism

97. 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.

98. • 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

99. • COMPLICATIONS
– Interlenticular opacification
• (Interpseudophakos Elshnig’s pearls)
• (RED ROCK SYNDROME)
– Unpredictable final IOL position

100. 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

101. • 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)

102. RECENT ADVANCES AND THE FUTURE
• LIGHT ADJUSTABLE IOL
• TELESCOPIC IOLs
• SMART IOLs
• ELECTRONIC IOLs

103. 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

104. • Sunglasses for about three weeks

105. 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.

106. • 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

107. • 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

108. 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.

110. SMART IOL

111. 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

112. 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

113. • Theoretical formulae
• Regression formulae

114. • 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

115. 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

116. • 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

117. 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

118. • 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

119. • SRK 2 formula
– Axial length 21-22mm, add 1 to A
– 20-21 add 2
– < 20 add 3
– Over 24.5mm subtract 0.5

120. • 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

121. • The Hoffer-Q formula
– Dr. Kenneth Hoffer in 1993
– P = f (A, K, Rx, pACD)
– short eye balls

122. • HAIGIS Formula
– also called the
GOW 70 formula
– Gernet, Ostholt
and Werner in
1970

123. • 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

124. • 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

125. • Nine types’ of eyes model

126. • available as part of a package called the
‘Holladay IOL consultant
• entire range of axial lengths

128. IOL injectors
• Preloaded
• Easy loading
• Basic type
• Autosert (alcon)

129. MANUFACTURING PROCESS
• MOLDING
• LATHE CUT
• TUMBLE POLISH

130. THANK YOU