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some information about intraocular lens materials, designs; and their effect on surgery and visual function. I'm sorry that i one i previously uploaded was the wrong file.
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Nawat Watanachai2013
1949 Sir Harold Ridley (UK)
1952 : Baron (FRA)
1953 : Edward Epstein (USA)
More than 250 models of IOL to be chosenWhich one is the best choice?
Which one is the best (+affordable)
choice?Patient’s satisfaction
▪ Good VA/ wide range of vision▪ Less aberration/ glare▪ safe▪ Reasonable price
Which one is the best (affordable) choice? Doctor’s satisfaction
▪ Easy to handle/ insert/ remove▪ Chemically inert/ noncarcinogenic/ nonallergic▪ Low bacteria and fungus adherence▪ Durable▪ Others :
▪ high RI/ absorp UV/ transparent for visible light
Materials Optical part : clear/ biocompat/ durable Haptic part
Designs Optical part : less PCO/ less aberration/
UV filter Haptical part : stability/ easily
insert+remove
Optics Glass Silicone-based Acrylate-Methacrylate-Based
Haptics Silicone-based Acrylate-Methacrylate-Based Polyamide Polyethylenglycolterephthala
te Polypropylene Polyimide
Glass Silicone-Based Acrylate-Methacrylate-Based
Polymethylmethacrylate monomer (PMMA) Rohto, PH55MB, P366UV, EZE55, SF65
Acrylic polymers Hydrophilic Acrylic polymers
Hydrogel
Hydrophobic Acrylic polymers Acrysof, Akreos, Sensar, Clariflex, Tecnis
Refractive index = 1.49AdvantagesCheap Transmit a broad light spectrum Surface modification Good biocompatibility Large optic center
Disadvantages Large incision size Brittle Monomeric release Not autoclavable Injure cornea
one-piece PMMA PC-IOLPH55, MC60BM, RohtoRE06F,
Epoch651A,Crystalfor Scleral fixationP366UV, SF65AC IOLS122UV
Disadvantages The lowest threshold for YAG laser
damage Discoloration of lens to a tan-brown color Irreversible adherence to silicone oil Foggy when exposed to airflow Slippery when wet
SI-30 design (AMO)SI-40 design (AMO)CeeOn Edge 911 (Pfizer)Clariflex (AMO)SoFlex SE (B&L)
Advantages Good biocompatibility,optical quality Foldable Good laser resistance Little or no surface alteration or damage
from folding Low damage potential when
touching the corneal endothelium
The Hydroview lens (B&L)The MemoryLens (Ciba Vision)The CenterFlex Lens (Rayner)
Developed for IOLPure acrylic polymer (flexibility) +
Methacrylic polymer (durability)
Advantages Foldable High refractive index (1.55) Good biocompatibility, optical quality High tensile strength VS hydrophilic Low water content/ no hydration require
Disadvantages Limit (very) long term
study Easily get forceps marks Sticky surface
PMMA Hydrophilic acrylic
Hydrophobic acrylic
silicone
RI 1.49 1.45-1.52 1.45-1.55 1.41-1.46
Biocompatibility
+ ++ ++ +++
Surface smoothening
++ + + +
Surface modification
- +++ +++ ++
PMMA Hydrophilic acrylic
Hydrophobic acrylic
silicone
Incision size
Large Smallest Smallest small
Non-Slippery when wet
+ + + --
Unfolding 0 + - -
Less mechanical corneal damage
-- ++ ++ ++
PMMA Hydrophilic acrylic
Hydrophobic acrylic
silicone
Less pigment adhesion
++ - ++ ++
Less LEC outgrowth
++ -- ++ +
Laser resistance
- ++ ++ --
Less Silicone oil adhesion
++ + + ---
Optical part : clear/ less PCO/ less aberration
Haptical part : stability/ easily insert+remove
germinal cells migrate centrally from equator contribute to the formation of
the nucleus , epinucleus and cortex throughout life
Square posterior edge
Square posterior edge360 barrier
ProTEC™ 360° Edge Design The 360° square edge Uninterrupted contact
with the posterior capsular bag even at the haptic-optic junction
The frosted-edge design minimizes edge glare
35
PCO
Acrysof
Akreos Tecnis
Posterior square edge
+ + +
IOL design : Spherical aberration
Spherical aberrations of the human eye vary with age
Cornea : always gives positive spherical
aberrations
Young lens :negative spherical aberrations old lens : positive spherical aberrations
glare,reduce contrast
In aviation-type visual performance testing, vision in low-light conditions (5 mm pupil)Does not allow a lens to bring light rays to an ideal focal pointThe effect may be a reduction in contrast sensitivity or visual function*
IOL With Residual Spherical Aberration*
IOL With No Residual Spherical Aberration
Spherical IOL The thicker the lens, the
greater the spherical aberration More power, increase
IOL thickness IOL thickness <-- RI
AcrySof (+20D) Silicone (+20D)
* DA Atchison, JCRS 1991
Aspheric optics align the light rays to compensate for Aspheric optics align the light rays to compensate for positive corneal spherical aberration, resulting in enhanced positive corneal spherical aberration, resulting in enhanced image quality.image quality.
*Smith, G., Atchinson D.A., (1997) The Eye and Visual Optical Instruments. Cambridge University Press, Cambridge, United Kingdom, pp. 667.
Aspheric IOL
Acrysof IQ ( SN 60 WF) (Alcon)
Akreos AO (Bausch & Lomb)
Tecnis Z 900 (AMO)
IQ’s posterior aspheric optic Compensates for spherical aberration by
addressing over-refraction at the periphery No increase in edge thickness Lenc become thinner
Aspheric IOL
Trim both anterior and posterior surfaces
Creates asphericity by elevating the peripheral portion of the anterior lens surface
Edge thickness of approximately .60 mm
Spherical aberration
Acrysof Akreos Tecnis
Correction area
Trim posterior center
Trim anterior / posterior center
Add anterior rim
Lens thickness
Thinner at center
Thinner at center
Thicker at rim
511. Schwiegerling J. Survey of Ophthalmology, 2000.
52
may negatively impact: Visual acuity Contrast sensitivity Functional vision
Abbe numbers
The higher the Abbe number- lower the chromatic aberration - higher the retinal image quality
Negishi K, et al. Arch Ophthalmol .2001.
A higher Abbe number is better: this means less chromatic aberration and better optical performance
Acrysof (Alcon) 37Akreos (B&L) 47Tecnis (AMO) 55
A higher Abbe number is better: this means less chromatic aberration and better optical performance
Acrysof (Alcon) 37Akreos (B&L) 47Tecnis (AMO) 55
551. Schwiegerling J. Survey of Ophthalmology, 2000.
Acrysof (Alcon)
Akreos (B&L)Tecnis
(AMO)
ALL CHECKED
UV blocker (350-400 nm)Blue blocker (blue 400-480 nm)
Filters for invisible UV rays some visible blue rays
Block visible blue rays? Blue ray :
7% of cone related photopic vision 35% of rod related scotopic vision
Patients with blue light-filtering IOLs had faster response times in driving Gray R. J Cataract Refract Surg. 2011
Blue light-filtering IOLs helped to lower glare disability and increase photostress recovery time Hammond. Clin Ophthalmol. 2010
Block only the UV lightNOT the BLUE
Blue light is proven to be essential for optimal scotopic vision*
Blue light provides 35% of scotopic sensitivity*
*Mainster MA. Br J Ophthalmol. 2006. 61
Interest in blocking blue-light is motivated by the unproven hypothesis that phototoxicity from environmental light exposure can cause AMD*
10 of 12 major epidemiological studies show no correlation between AMD and lifelong light exposure
62 Mainster MA. Presented at ASCRS .2009.
Acrysof Akreos Tecnis
A 118.7 118.5 118.8
Hydrophobic acrylic
yes yes yes
RI 1.55 1.458 1.47
Abb no 37 47 55
UV blocker + + +
Blue blocker
+ - -
Acrysof Akreos Tecnis
Haptic angulation
0 10 5
Haptic shape
J Loop L
Block Spherical aberration
YesPost.trim
YesAnt. + Post.trim
YesAnt.add
Thickness at same power
thinnest fair thickest
Toric IOLsMultifocal IOLsAccommodative IOLs IOLs for very small incision Adjustable power IOLs Phakic IOLs
To reduce pre-existing astigmatismNeed appropriate centration, fixation
and stability without rotational movement
Preexisting regular astigmatism 0.75>D More problem if axis is away from 90/
180’Regular and smooth keratoscopic
mires with orthogonal steep and flat meridians
Irregular astigmatismDistorted keratometryA lifelong patient history of
satisfaction with spectacular cylindrical corrections
Large eyes (white-to-white distance > 12 mm)
Postoperative rotation or decentration will cause problems
negative effect can occur if the lens axis rotates by more than 30’
Coming soon
My opinion : when to consider toric IOL Astigmatism >1.5 at 90’ or 180’ Astigmatism 1.0 at other axes
distance and near visionRequire
astigmatism controlprecise biometry
Types of multifocal IOLs Refractive multifocal IOLs
▪ Spheric▪ Aspheric Diffractive multifocal IOLs
Array Design multifocal IOLs (AMO) Three-piece Silicone with PMMA haptic zonal multifocal optic with 5 concentric
zones▪ Zone 1, 3,5 – distance▪ Zone 2,4 -near
Array Design multifocal IOLs (AMO) Anterior spheric refractive surface and
multiple posterior refractive surface Power 0-5.0 D vision
▪ Distance vision 50 %▪ Intermediate vision 13 %▪ Near vision 37 %
The ReSTOR (Alcon) Single-piece The diffractive grating is present in the center 3.6
mm The largest diffractive step is at the lens center
▪ send most energy to the near focus As the step move away from the center,they
gradually decrease in size ,blending into the periphery▪ sending more proportion of energy to the distance focus
▪ When the pupil is small or medium size▪ provides appropriate near and distant
vision▪ large pupil situations
▪ becomes a distant-dominant
Problems and complications loss of contrast sensitivity pupillary apertures <2 mm
decrease in distance VA decentered > 2 mm
loss of near VA visual performance is minimally
affected by decentration and changing pupillary size
Problems and complications (cont’d) Ghosting of images and glare from
oncoming light
Refractive Diffractive
Near VA - +
Distance VA = =
Contrast sensitivity
better worse
glare Less more
Array AcrysofReSTORTecnisMF
▪ Pros▪ Offer ranges of vision
▪ Cons▪ Not offer good vision in all ranges▪ 30% still need reading glasses
▪ PCO will cause more visual problems▪ More glare▪ Less contrast sensitivity
▪ Need good IOL positioning Round CCC Clear capsular bag Tilt < 5-6’
Price tag
To restore accommodation forward movement of the optic during
accommodationIt is still not known whether the
ability of these new IOL design will not be impair by long-term postoperative fibrosis/ opacification within the capsular bag
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
synchrony IOL (Visiogen Inc.) One-piece silicone lens The anterior lens has a high plus power
beyond that required to produce emmetropia(30-35 D)
the posterior lens has a minus power to return the eye to emmetropia
The distance between the two optics• minimum in the un-accommodated state• maximum in the accommodated state
No long term data
FluidVisionPocket filled
with clear liquid silicone
• Calhoun lens•University of California at San Francisco, San Francisco, California
There is no BEST IOL for allFind the proper one for each patients