Intra ocular lens
-
Upload
vishnu-narayanan -
Category
Health & Medicine
-
view
4.649 -
download
9
description
Transcript of Intra ocular lens
![Page 1: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/1.jpg)
INTRA-OCULAR LENSVISHNU NARAYANAN
![Page 2: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/2.jpg)
What is intraocular lens?
• An artificial lens implanted in the eyes• Replaces the crystalline lens• To correct the optical power of the eyes
following:-
Lens being clouded by
cataractRefractive surgery
![Page 3: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/3.jpg)
Primary vs secondary implantation
• Primary implantation – use of IOLs during surgery for cataract
• Secondary implantation – implantation of IOL to correct aphakia in a previosly operated eye
![Page 4: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/4.jpg)
Parts of an IOL• 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
HAPTENOPTIC
![Page 5: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/5.jpg)
HISTORY OF IOL
• K
![Page 6: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/6.jpg)
THE FIRST IOL!!• PMMA made lens – 45 year
old female after performing extracapsular cataract extraction
• Disc shaped bi-convex design• Site- posterior chamber• First generation IOL
![Page 7: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/7.jpg)
EVOLUTION OF IOLs1. First generation IOLs• Ridley lenses• Disadvantages – posterior dislocation poor surgical technique2. Second generation IOLs• Rigid and semi-rigid anterior chamber IOLs• Advantages – reduce posterior dislocation• Disadvantage – corneal decompensation UGH syndrome
![Page 8: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/8.jpg)
3. Third generation IOLs
• Iris supported lens• Advantages- less corneal decompensation• Disadvantages – iris chaffing pupillary distortion c/c inflammation cystoid macular edema
![Page 9: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/9.jpg)
4. Fourth generation IOLs
• Modern anterior chamber lens• Flexible loops and multiple point fixation• Advantages – more stable, better design, less
complications• Disadvantages – anterior chamber is not the
physiological site for IOL
![Page 10: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/10.jpg)
5. Fifth generation IOLs
• PMMA lenses• Foldable and small incision lenses
![Page 11: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/11.jpg)
MATERIALS USED FOR INTRAOCULAR LENSES
Optic materials
1.Non-foldable-rigid IOL• Polymethyl
methacrylate(PMMA)
2.Foldable IOL• Silicone• Hydrophobic acrylic• Hydrophilic acrylic
3.Rollable/Ultra-thin IOL• hydrogel
Haptic materials
• Polypropylene• PMMA• Acrylic
![Page 12: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/12.jpg)
POSITIONING OF IOL
1. Posterior chamber implantation
• Ciliary sulcus fixation
• In the bag fixation
• Scleral fixation
Eg:- modified C loop type IOL
![Page 13: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/13.jpg)
Ciliary sulcus fixation
![Page 14: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/14.jpg)
In-the-bag fixation
![Page 15: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/15.jpg)
Scleral IOL
![Page 16: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/16.jpg)
2. Anterior chamber implantation
• angle supported IOLs
• Kelman multiflex type IOL
![Page 17: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/17.jpg)
3. Iris- fixated lens
• Fixed on the iris with claws,loops or sutures
• Eg- Singh and Worst’s iris claw lens
![Page 18: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/18.jpg)
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
![Page 19: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/19.jpg)
![Page 20: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/20.jpg)
FOCUSSING ABILITY OF IOLs
1. Unifocal intraocular lens
• Lens with unifocal power• Can have problem with near vision
![Page 21: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/21.jpg)
2.Multifocal IOLs
• Simultaneous vision lenses
• Based on either refractive or diffractive optics
• Psuedoaccomodation lens
![Page 22: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/22.jpg)
3.Accomodative IOLs
• Exhibit anterior movement of optic to improve near vision
![Page 23: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/23.jpg)
Special function IOLs
TORIC IOLs• Correct any associated astigmatism
ASPHERIC IOLs• Reduce spherical aberration
![Page 24: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/24.jpg)
ANIRIDIA IOLs• Cover the defects of aniridia or
partial iris loss as in trauma• Has a black diaphragm over the
optic
PIGGYBACK IOLs• An IOL piggybacking onto an
existing IOL or simultaneous implantation of 2 IOLs
![Page 25: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/25.jpg)
BLUE LIGHT FILTERING IOLs• Lenses are yellow colored to screen out UV
Light and blue spectrum• Reduced risk of age related macular
degeneration
PHOTOCHROMATIC IOLs• UV absorbing photo chromes
![Page 26: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/26.jpg)
IMPLANTABLE MINIATURE TELESCOPE• Miniature implantable Galilean
telescope• Implanted in posterior chamber• Contains number of micro lenses
in the optic which gives a magnification of about 3 at the central visual field
• Used to treat macular degeneration
![Page 27: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/27.jpg)
TELESCOPIC IOLs
• New generation miniature telescopes which uses 2 mirrors instead of lens to provide magnification with minimum loss of peripheral vision
![Page 28: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/28.jpg)
Phakic IOLs
• IOLs used to correct myopia with the eye’s natural lens being untouched
• Implantable contact lenses1. Angle supported lens2. Iris – fixated lens3. Sulcus supported lens
![Page 29: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/29.jpg)
BIOMETRY
THEORETICAL FORMULAE• Binkhorst formula• Colenbrander’s formula• Gull strand’s formula• Hoffer’s formula
EMPERICAL FORMULAE• Modified Sanders-Retzlaff-Kraff formula• SRK II• SRK III• SRK T• Haigis formula
![Page 30: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/30.jpg)
Binkhorst formula
• E= [N/(L-C)] – NK/(N-KC)]
E• Emmetropic IOL power
L• Axial length of the eye
K• Corneal dioptric power
C
N
• Psuedophakic length of anterior chamber
• Refractive index of aqueous and vitreous humor
![Page 31: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/31.jpg)
Modified Sanders-Retzlaff-Kraff formula
• Based on the statistical correlation between calculated and observed refractive error after ocular implantation.
![Page 32: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/32.jpg)
Modified SRK Formula• E=A - 2.5L - 0.9K• Parameters used in the formula are
estimated by• A-scan ultrasonographic sonometry and
keratometry• Instrument - biometer
![Page 33: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/33.jpg)
E=A - 2.5L - 0.9K
E:Emmetropic power of eye
A:Predetermined constant of IOL
L: Axial length in mm
K:Average of keratometry readings
![Page 34: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/34.jpg)
• Power ( I )required to produce Required post operative refraction ( R ) ,
I = E – cr R
• cr – empirical constant cr = 1 if E < 14 cr = 1.25 if E > 14
![Page 35: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/35.jpg)
Complications of IOL implantation
• Mechanical damage to the IOL• Dislocation• Bullous keratopathy• Posterior capsule rupture• Anterior capsule opacification• Posterior capsule opacification• Calcium deposits within the optic of hydrophilic intraocular
lens• Adherence• UGH syndrome• Sunset syndrome
![Page 36: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/36.jpg)
Sunset syndrome
![Page 37: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/37.jpg)
“Lens of the future”-liquid injectable IOLs
• A new IOL concept that combines an acrylicIOL with a liquid, injectable IOL may somedayallow patients to retain accommodation.
• Following IOL implantation, liquid IOL is injected and capsular bag is inflated fully and IOL kept in place
• Mechanism- forward movement and thickening of lens
![Page 38: Intra ocular lens](https://reader034.fdocuments.in/reader034/viewer/2022052321/554b8014b4c90561588b4bf2/html5/thumbnails/38.jpg)
THANK YOU….