Intra ocular lens
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An intraocular lens (IOL) is an artificial lens implanted in the eye during cataract surgery or refractive lens exchange to replace the natural crystalline lens and correct vision. IOLs have evolved over generations from rigid PMMA lenses to modern foldable designs made of silicone, acrylic, or hydrogel materials. IOLs are either placed in the posterior chamber behind the iris or in the anterior chamber in front of the iris. Newer multifocal and accommodating IOL designs aim to provide both distance and near vision. Precise biometry is required to calculate the optimal IOL power to achieve the desired postoperative refraction. Potential complications include dislocation, opacification, deposits, and inflammation.
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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
Editor's Notes
- No loss of peripheral vision