Intra ocular lens
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a seminar about intraocular lenses,their types , uses and complications
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Intra ocular lens
- 2. 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 cataract Refractive surgery
- 3. 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
- 4. 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 HAPTEN OPTIC
- 5. HISTORY OF IOL • K
- 6. 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
- 7. EVOLUTION OF IOLs 1. First generation IOLs • Ridley lenses • Disadvantages – posterior dislocation poor surgical technique 2. Second generation IOLs • Rigid and semi-rigid anterior chamber IOLs • Advantages – reduce posterior dislocation • Disadvantage – corneal decompensation UGH syndrome
- 8. 3. Third generation IOLs • Iris supported lens • Advantages- less corneal decompensation • Disadvantages – iris chaffing pupillary distortion c/c inflammation cystoid macular edema
- 9. 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
- 10. 5. Fifth generation IOLs • PMMA lenses • Foldable and small incision lenses
- 11. 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
- 12. POSITIONING OF IOL 1. Posterior chamber implantation • Ciliary sulcus fixation • In the bag fixation • Scleral fixation Eg:- modified C loop type IOL
- 15. Scleral IOL
- 16. 2. Anterior chamber implantation • angle supported IOLs • Kelman multiflex type IOL
- 17. 3. Iris- fixated lens • Fixed on the iris with claws,loops or sutures • Eg- Singh and Worst’s iris claw lens
- 18. 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
- 20. FOCUSSING ABILITY OF IOLs 1. Unifocal intraocular lens • Lens with unifocal power • Can have problem with near vision
- 21. 2.Multifocal IOLs • Simultaneous vision lenses • Based on either refractive or diffractive optics • Psuedoaccomodation lens
- 22. 3.Accomodative IOLs • Exhibit anterior movement of optic to improve near vision
- 23. Special function IOLs TORIC IOLs • Correct any associated astigmatism ASPHERIC IOLs • Reduce spherical aberration
- 24. 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
- 25. 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
- 26. 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
- 27. TELESCOPIC IOLs • New generation miniature telescopes which uses 2 mirrors instead of lens to provide magnification with minimum loss of peripheral vision
- 28. Phakic IOLs • IOLs used to correct myopia with the eye’s natural lens being untouched • Implantable contact lenses 1. Angle supported lens 2. Iris – fixated lens 3. Sulcus supported lens
- 29. 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
- 30. 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
- 31. Modified Sanders-Retzlaff- Kraff formula • Based on the statistical correlation between calculated and observed refractive error after ocular implantation.
- 32. 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
- 33. E=A - 2.5L - 0.9K
- 34. • 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
- 35. 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
- 36. Sunset syndrome
- 37. “Lens of the future”-liquid injectable IOLs • A new IOL concept that combines an acrylic IOL with a liquid, injectable IOL may someday allow 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
Notas do Editor
- No loss of peripheral vision