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RECENT ADVANCES IN INTRAOCULAR LENS

recent advances in intraocular lens

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RECENT ADVANCES IN INTRAOCULAR LENS

  1. 1. RECENT ADVANCES IN IOLS Dr. Laltanpuia Chhangte GMC ,HALDWANI
  2. 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. 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. 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. 5. HISTORY OF IOL • K
  6. 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. 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. 8. 3. Third generation IOLs • Iris supported lens • Advantages- less corneal decompensation • Disadvantages – iris chaffing pupillary distortion c/c inflammation cystoid macular edema
  9. 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. 10. 5. Fifth generation IOLs • PMMA lenses • Foldable and small incision lenses
  11. 11. MATERIALS USED FOR INTRAOCULAR LENSES Optic materials 1.Non-foldable-rigid IOL • Poly-methyl methacrylate(PMMA) Water content <1% Refractive index 1.49 Usually single piece May be penetrated by aqueous humor known as ‘glistenings’ (very rare) 2.Flexible IOLs • Silicones • Hydrophobic acrylic • Hydrophilic acrylic • Hydrogel • Collamer
  12. 12. Features of IOL
  13. 13. INTRAOCULAR LENS DESIGN • Single piece / monobloc • Plate haptic / open loop haptics • Angulated / planar haptics • Edge design • Optic design
  14. 14. 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
  15. 15. ANGULATED HAPTICS ALLOW FOR ADEQUATE PUPILLARY CLEARANCE AND ADHESION TO THE POSTERIOR CAPSULE
  16. 16. ………
  17. 17. Square, truncated optic edge
  18. 18. Suitable position for implanting IOL in eye • Best placed in posterior chamber in the capsular bag.
  19. 19. ADVANTAGES OF IN-THE-BAG PLACEMENT • Proper anatomical site • Symmetrical loop placement • Intraoperative stretching or tearing of zonules is avoided • Minimal 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 • Reduced posterior capsular opacification
  20. 20. POSITIONING OF IOL 1. Posterior chamber implantation • Ciliary sulcus fixation • In the bag fixation • Scleral fixation Eg:- modified C loop type IOL
  21. 21. In-the-bag fixation
  22. 22. OTHER POSITIONS: • Posterior capsule tear • zonular dialysis
  23. 23. Ciliary sulcus fixation
  24. 24. Scleral IOL
  25. 25. 2. Anterior chamber implantation • Angle supported IOLs • Iris fixated e.g Kelman multiflex type IOL
  26. 26. 3. Iris- fixated lens • Fixed on the iris with claws,loops or sutures • Eg- Singh and Worst’s iris claw lens
  27. 27. BASED ON OPTICAL CORRECTION 1. Mono-focal intraocular lens • Lens with uni-focal power • This common IOL type has been used for several decades . • Mono-focals are set to provide best corrected vision at near, intermediate or far distances. • Most people who choose mono-focals have their IOLs set for distance vision and use reading glasses for near activities. • Some who choose mono-focals decide to have the IOL for one eye set for distance vision, and the other set for near vision, a strategy called "monovision."
  28. 28. …….. • The brain adapts and synthesizes the information from both eyes to provide vision at intermediate distances. People who regularly use computers, PDAs or other digital devices may find this especially useful. • Individuals considering monovision may be able to try this technique with contact lenses first to see how well they can adapt to monovision. • Those who require crisp, detailed vision may decide monovision is not for them. People with appropriate vision prescriptions may find that monovision allows them see well at most distances with little or no need for eyeglasses.
  29. 29. 2.Multifocal IOLs • Single IOL with two or more focal points • Refractive • Diffractive • Combination of both • Simultaneous vision lenses • Pseudo-accommodation
  30. 30. Multifocal IOLs • Multifocal iols have the advantage of providing patients with functional vision at near ,far and at intermediate distances. • Patients can have a traditional monofocal iol with a refractive target of emmetropia,mild myopia,or monovision(1 eye distance,1eye near) • The Array (AMO),Santa ana CA multifocal silicone PCIOL was the first multifocal IOL to be granted fda approval in US. • Three mutifocal lenses are currently FDA approved for use after cataract extraction: • ReZoom lens(AMO),The Acrysof ResTOR(alcon) and Technis(AMO) multifocal iols
  31. 31. ReZoom lens • Flexible,3-piece , acrylic, distance dominant zonal refractive IOL • Insertion through 2.8 mm CCI • 5 expanded refractive zones within the 6 mm optic & produces 2.80 D of near power • Pupil must be 2 mm to reach the near effect
  32. 32. Multiple focal points of a refractive multifocal IOL
  33. 33. DIFFRACTIVE MULTIFOCAL IOLs • Anterior aspheric surface : basic refractive power • Multiple grooves on posterior surface : diffractive power • 41% of light : distance • 41% : near vision • Pupil independent
  34. 34. Multiple focal points of a diffractive multifocal IOL
  35. 35. Acrysof ReSTOR lens(alcon lab) • FDA approved in 2005 • 1/3 piece ,acrylic ,aspheric ,foldable ,diffractive lens that simultaneously focuses light on both near and distance targets • Central 3.6mm difrractive zone is mainly for near and outside that is for distant vision • Loss of 6%-19% light which affects contrast sensitivity esp in patients with smaller pupils • ReSTOR IOL is manufactured with +4.00 D+3.00D add at IOL plane. • Patients who received +4.00D expressed dissatisfaction with the near focal point being too close
  36. 36. Tecnis Multifocal IOLs (AMO) • FDA approved in 2009 • Foldable,hydrophobic,diffractive aspheric acrylic lens • The diffractive steps are on the posterior aspect on the lens and extend fully to the periphery. • Diffractive Power +4.0 diopters of near addition (+3.0 Diopters at spectacle plane)
  37. 37. Patient selection • Relatively easy going people who place a high value on reducing dependence on glasses or contact lenses • Good potential vision • <1.00D preexisting corneal astigmatism • Demanding patients strictly avoided Special considerations: • Counselling (most important) • Accurate Biometry • IOL master strongly recommended
  38. 38. Surgical technique • Same as in standard SICS with a foldable acrylic IOL • Round, centered CCC completely overlapping the lens optic • Removal of all viscoelastic from behind the lens • Optimal refractive effects depend upon good centration • Discouraged in case of inadequate centration or if posterior capsule is not intact
  39. 39. Side effects and complications • Capsular opacification • Glare,halos,and ghosting than a monofocal IOL or an accommodating IOL • Decreased contrast sensitivity • Intermediate vision may be weaker with multifocal IOLs than an accommodating one • Requires Visual-Cortical Neuro-adaptation
  40. 40. Preferances
  41. 41. 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. 42. 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
  43. 43. ASPHERIC IOLs Advantages Disadvantages
  44. 44. ACCOMMODATIVE IOLs • Monofocal IOL • To restore a significant amount of true accommodation to patients with surgically induced pseudophakia. • During ciliary muscle contraction,forward displacement of the IOL led to an increase in the IOLs effective power and thus an improvement in near vision. • 1 mm of anterior movement of lens = 1.80 D of accommodation • Mimicking the eye's natural ability to focus Crytalens ( Baush & Lomb):modified silicone, plate haptic(hinged),biconvex optic which potentially allow anterior movement of the lens during accommodation.
  45. 45. Accomodative IOLs • Another theory is ciliary muscle contraction causes a steepening of anterior optic surface allowing for better near vision. • Only FDA approved IOL for correction of presbyopia
  46. 46. • Although the exact cause of movement is unclear,it appears to be the a combination of posterior chamber pressure on the back surface of iol and Cilliary Body pressure on the iol haptics that vaults the optic forward. • As the ciliary body contracts,increased pressure is transmitted via vitreous to polyamide haptics & the compression betwwen the haptics causes the optic to bow forward • Accomodative arching of the lens enhances depth of focus Hydrophilic Acrylic,single optic • BioComFold type 43E (Morcher GmbH) • 1CU (HumanOptics AG) • Tetraflex (Lenstec Inc.) Development is also currently underway for dual optics IOLs eg,Sychrony IOL(visiogen,Irvine,CA) and deformable IOLs(smart IOL)
  47. 47. 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.
  48. 48. TORIC IOLs • 15-29% of patients undergoing cataract surgery have substantial corneal astigmatism >=1.50 D • Either we go for arcuate keratotomy or limbal relaxing procedures or alternatively a toric IOL can incorporate the astigmatic correction into the spherical IOL power.
  49. 49. INSTRUMENTATION • STAAR toric IOL • First FDA approved (in 1998) toric IOL • Single piece,plate haptic,foldable silicone IOL designed to be placed in capsular bag using an injector through a 3mm incision.once in the eye ,it must be oriented with its long axis precisely in the steep meridian. • 6mm biconvex optic with a spherocyndrical anterior and spherical posterior surface. • Spherical power in the range of =9.5 to =28.5 D with a choice of cylindrical powers of 2.00 and 3.50D which correct 1.50 and 2.25 D of astigmatism respectively
  50. 50. ……… • AcrySof IQ Toric IOL (Alcon Labs, USA) • Recently approved by FDA • 6mm biconvex acrlic optic,available in the range of +6 to +30 D & 3 astigmatism powers :+1.50 D,+2.25D and +3.00 D which correct +1.03,+1.55&+2.06 D respectively • Posterior surface has added cylindrical power and axis markings on the lens optic
  51. 51. Patient selection • CANDIDATES > or = 1.0D i.e mild to moderate regular corneal astigmatism • Patients with astigmatism in amounts exceeding the upper correction limits of these lenses may require additional measures to obtain full correction • Limitations of toric iols must be explained before hand • Patients should be infrmed as the lens may rotate within capsular bag • Inappropriate for the Patient who may require silicone oil for RD repair in future
  52. 52. Planning and surgical technique • Amount and axis of astigmatism should be measured accurately with a keratometer or if possible coneal topography • AcrySof Toric IOL Calculator generates correct power and model lens as well as orientation of the lens alignment markers • compensates for surgically induced astigmatism
  53. 53. …….. • Vertical& horizontal meridians should be marked on the cornea with the pt in an upright position. • reference marks at the 3- and 9-o’clock • After the IOL is injected into the capsular bag viscoelastic material behind the IOL is aspirated and the IOL is rotated into the position on the steep meridian • It may roate when balanced saline solution is injected to reform the AC • Final alignment
  54. 54. Complications • Possibility of IOL rotation as full correction is not achieved unless the IOL is properly aligned in the axis of astigmatism According to STAAR,a 10 degree off axis rotation reduces the correction by approx. 1/3rd • 20degree by 2/3rd • And an off axis correction of more than 30 dregree can actually increase the cylindrical refractive error. • When a plate haptic toric IOL is used,surgeon should take care when performing Nd:Yag capsulotomy .if the capsulotomy is too large a plate haptic may prolapse posteriorly Typically a misaligned IOL is recognized within days of surgery,it should be repositioned before permanent fibrosis occurs within capsular bag.
  55. 55. 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 Eg: • Acrismart • Thin Optx ultrachoice • Slimflex lens
  56. 56. ANIRIDIA IOLS • Cover the defects of aniridia or partial iris loss as in trauma • Has a black diaphragm over the optic
  57. 57. Phakic IOLS
  58. 58. 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.
  59. 59. Types • Posterior Chamber • Iris fixated • Angle fixated
  60. 60. Patient selection • Patients who are near or beyond the FDA approved limits for laser vision correction • Patient with extreme corneal curvatures(flatter than 34 D in myopics corrections and steeper than 50 D in hyperopic corrections after laser refractive surgeries) CONTRAINDICATIONS: Patients with compromised corneal endothelium,iritis,rubeosis iridis,cataract & glaucoma • Informed consent must be taken Ancillary tests :specular microscopy,corneal pachymetry and AC depth
  61. 61. SURGICAL TECHNIQUE • TA with an intracameral supplement is appropriate and PIOL is inserted through a small incision • A perpipheral iridotomy is recommended for all currently FDA approved PIOLs reduce the risk of puppilary block and angle closure. • Preoperative iridotomy is preferable when small incision implant surgery is performed bcoz surgical iridotomy or iridectomy is technically difficult to perform through beveled clear corneal incision • Viscoelastic material should be meticulously removed at the conclusion of surgery to prevent post op IOP spike.
  62. 62. Posterior chamber phakic lens • Implantable collamer lens (ICL) (VISIAN; STAAR) • Sticklens Correct IOL length is selected by using the white to white measurement between 3 and 9 o clock positions.
  63. 63. Implantable Collamer Lens (ICL) • Pre-crystalline lens made of silicone or collamer • Co-polymer of HEMA(99%)+Porcine collagen(1%) Overall size- 11-13 mm Optical zone - 4.5-5.5 mm • Optic of the PCPIOL is vaulted both to avoid contact with the crystalline lens ans to allow aqueous to flow over the crystalline lens • Currently approved for myopes with - 3.00D TO -20.00D in adults 21-45 age group with a minimum AC dephth=3 mm Avoid touching the central aprt of crystalline lens
  64. 64. COMPLICATIONS: • Endothelial cell damage • Inflammation • Pigment dispersal • Elevated IOP • Cataract
  65. 65. IRIS FIXATED PHAKIC IOL • VERISYSE/ARTISAN (AMO/OPTECH): • Myopia -5.00 to -20.00 D in patients 21 yrs or older ,min. AC depth 3.2 mm • Made of PMMA,convexo- concave,Length = 8.5 mm,Optic size = 5-6 mm • Claw Haptics fixed to iris by a encavation process • Generally inserted through a superior limbal incision with side ports are made at 10 & 2 o clock positions. • Specialised encavation needle is introduced from one of the side ports and a knucle of iris is brought up into the claw haptic
  66. 66. 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 • De-centration • Endothelial cell loss
  67. 67. ANGLE FIXATED PHAKIC IOL • TWO TYPES- -4 point fixation • Baikoffs modification of Kelman type haptic design -3 point fixation • Vivarte(IOLtech) • Can be inserted through a temporal clear corneal incision or a scleral pocket • No ACPIOL is currently FDA approved
  68. 68. Complications Endothelial cell loss Irregular pupil Iris depigmentation Post-op inflammation Halos and glare Surgical induced astigmatism
  69. 69. 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.
  70. 70. • 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
  71. 71. COMPLICATIONS • Interlenticular opacification • (Interpseudophakos Elshnig’s pearls) (RED ROCK SYNDROME) • Unpredictable final IOL position
  72. 72. THE FUTURE IOLs LIGHT ADJUSTABLE IOL TELESCOPIC IOLs SMART IOLs
  73. 73. LIGHT ADJUSTABLE IOLS Calhoun Vision • 3 piece Silicone optic PCIOL with two C-PMMA haptics • Silicone matrix has been embedded with silicone subunits called macromers. • Photosensitive to the near-ultraviolet wavelength of energy in a specific pattern,when irradiated with UV light through slit lamp delivery system ,the macromere polymerise and are depleted. • Monomers from the non irradiated part of IOL optic are in higher centre bcoz of induced osmotic gradient move to the centre and cause the IOL to swell up and increases the power of IOL • myopic adjustment : periphery of the lens • Final irradiation step locks in is done & IOL optic is diffusely irradiated within 1-2 weeks post op once the desired power has been acheived • Nomograms have been developed that can reportedly correct over a 5.00D range of myopia,hyperopia,astigmatism.
  74. 74. • Sunglasses for about three weeks
  75. 75. 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
  76. 76. 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
  77. 77. TELESCOPIC IOLs • New generation miniature telescopes which uses 2 mirrors instead of lens to provide magnification with minimum loss of peripheral vision
  78. 78. BIOMETRY THEOREITICAL 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
  79. 79. Modified SRK( Sanders-Retzlaff-Kraff formula) • E=A - 2.5L - 0.9K • Parameters used in the formula are estimated by • A-scan ultrasonographic sonometry and keratometry • Instrument - biometer Based on the statistical correlation between calculated and observed refractive error after ocular implantation.
  80. 80. E=A - 2.5L - 0.9K
  81. 81. • 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
  82. 82. Smart lens(medennium,irwine,CA) • Thermoplastic acrylic gel that can be customized into any size,shape,or power specified by the physician would allow the patients to retain accommodation. • The hydrophobic acrylic material is chemically bonded to wax,which melts inside the eye at body temperature & allows the predetermined shape,powe of the material to emerge. • Theoretically,compression of this pliable lens by the capsular bag would allow adjustment of its effective power in a manner similar to the way the crystalline lens adjusts. • Other examples of deformable IOLs that are still in preliminary stage of development are:Flexoptic(AMO),Fluidvision IOL(Power vision,Belmont ,CA),NuLens(NuLens,Israel)

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