Accommodating Intra Ocular Lenses


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Analysis of accommdation problem brought on by presbyopia and solutions in intra-ocular lens technologies available or in development toward market

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Accommodating Intra Ocular Lenses

  1. 1. Challenges and New Technologies for Accommodating Intra-Ocular Lenses in Presbyopia Alan N. Glazier, OD, FAAO 2013
  2. 2. Binocular Accommodation • Six components of Accommodation • Mechanics of Each Function Together to Provide Human Physiologic Binocular Accommodation • Four components recognized as vital – – – – increased convexity of the lens anterior movement of the lens miosis of the pupil convergence of the eyes • Two additional components; – pupillary compression – Gestalt (the “brain factor”) • No one component of accommodation can account for binocular near vision/All six must function
  3. 3. Importance of Accommodative Amplitude • • • Accommodative Amplitude – Latent and Manifest Ability of Ciliary Muscle to Exert and Sustain Effort on Ocular Lens at the Spectacle Plane “Pushing” does not equal “Sustaining” Sheard’s Criterion – Standard for Determining Sufficient Amplitude for Near Vision Sustenance; – • • One-Third to One-Half of the Accommodative Amplitude Needs to be Left in Reserve in Order to Allow for Sustained Near-Point Activity. (A patient able to achieve 2.5 D with an accommodative IOL should only be able to sustain use of perhaps 1.25 D freely - 2.5 D of accommodative amplitude does not equate with a 2.5-D bifocal add but more like a 1.25-D bifocal Add) Most Current Technologies Have Demonstrated Abilities of Slightly More Than 1.75 Diopters of Add Max Reading Comfortably at 33 cm Would Require 3 D of Power at Spectacle Plane (4.5 to 6 D of Accommodative Amplitude - Leaving 1/3 of Accommodation Left in Reserve).
  4. 4. Hinged Accommodating IOLs
  5. 5. Tetraflex
  6. 6. Kellan Tetraflex IOL • Small-Incision (2.5mm) Single-Optic Accommodative IOL. • Hydroxymethylmethacrylate • Has a 5.75- millimeter equiconvex optic and a square-edged design to inhibit posterior capsular opacification • Approved in Europe, Australia and the Middle East since 2003 • U.S. Trials are Beginning, With About 50 lenses Implanted to Date. On Sale in US
  7. 7. Crystalens (Bausch & Lomb)
  8. 8. Crystalens (Eyeonics) • The Crystalens is a modified, hinged, plate-haptic silicone lens with polyimide loops. The lens has a high refractive index of 1.43 with a UV filter. The length of the lens plate is 10.5 mm, with a total IOL length of 11.5 mm. The lens optic is biconvex with a diameter of 5 mm. The IOL offers near and intermediate focal ranges by way of anterior displacement of the lens optic due to fluctuating pressures within the vitreous cavity as the ciliary body contracts
  9. 9. Crystalens • Extra Power Provided by the CrystaLens May Not be Sufficient/May Still Require a Reading Add (Reading Add Still Required in About ½ of Patients) • Small Optic - Issue With Patients With Large Pupils/Significant Pupillary Dilation in Dim Light More Prone to Edge Glare • Mean Accommodative Amplitude 1.79 diopters (Dell, Steven, MD) 96% percent of eyes had a change in distance acuity of ? ±1.0 D
  10. 10.
  11. 11. ICU Akkommodative (Human Optics)
  12. 12. ICU Akkomodative • Foldable, Single-Piece IOL with an Optic Diameter of 5.5 mm and an Overall length of 9.8 mm. • Hydrophilic Acrylic material with a refractive index of 1.46. • Biconvex, Square-Edged Optic and Four Flexible Haptics that Bend When Constricted in the Capsular Bag After Ciliary Body Contraction.
  13. 13. ICU Akkomodative • Accommodating Mechanism Can Play Role in Capsule Fibrosis, Likely to Reduce Amplitude of Device as Patient Ages • Clinical Studies Report That Accommodation Amplitudes, 6 Months After the Operation, Mean Value Between 1.7 D and 1.9 D • Approximately 1.80 D of Accommodation Occurs Per 1 mm of Anterior Movement of the Lens Optic. (Langerbucher et al ) • Mean Accommodative Amplitude Produced 1.8D (Kuchle et al)
  14. 14.
  15. 15. Fibrosis – The Curse for Hinged Accommodating IOL’s • Short and long term study results show that capsule bag reduces accommodative powers of the eye through shrinkage and fibrotic processes • Often leads to IOL dislocation and explantation due to hinge optic designs. (Binder et al., Obertshausen, Germany) • If Lens Doesn’t Move as Expected it Results in Diminished Accommodative Capacity or Myopia at Distance (Blur) • Long-Term Stability of the Hinge and Accommodative Refractive Effect are not Known • Fibrosis Likely to Reduce Amplitude of Device Further as Patient Ages
  16. 16. Other Challenges • Increased Rate of CME Associated With Sulcus-Bag Placement of Haptics. • Effects of Vitrectomy on Accommodative Performance of “Movable” IOL’s are unknown. • Lower Powers → Less Accommodation • Capsular Contraction → Distortion and Decentration • Wound Leaks → Unexpected Myopia
  17. 17. Dual Optic
  18. 18. Sarfarazi Elliptical IOL (Bausch &Lomb)
  19. 19. Synchrony (AMO)
  20. 20. Synchrony • Designed With an Anterior High-Plus-Powered Lens and a Posterior Minus Lens • Pseudophakic Accommodation Occurs When Zonular Tension is Released During Ciliary Body Contraction Resulting in a Compression of the Optic and Spring Haptic. • Currently in Clinical Studies in the U.S. and Recently Received CE Mark in Europe
  21. 21. Synchrony Dual-Optic Accommodating IOL (Visiogen) • Model Calculated Approximately 2.20 D of Accommodation • Amplitude Measured at +2.50 (Burkhardt Dick, Cataract and Ref. Surgery, July 2004) • Mean Accommodative Amplitude 2.55 D ( study by Ossma-Gomez, Ivan MD) • Mean Monocular Amplitude of Accommodation : 3.17D
  22. 22.
  23. 23. NuLens
  24. 24. NuLens • Compressible Polymer Between Fixed Plates On Accommodative Effort Polymer Bulges Through Aperture in the Anterior Fixed Plate, Resulting in an Increase in the Steepness of the Anterior Surface. • Still in Animal Studies
  25. 25. NuLens • Progressive Capsular Contraction Following Cataract Extraction With Subsequent IOL Power Changes • Difficult Distance (contracted ciliary body) IOL Power Calculations • Optical Aberrations From Peripheral Portions of the IOL Not Undergoing Dynamic Power Changes • Accommodation Not Governable • Elderly Average Remaining Ciliary “Strength” Insufficient to Take Advantage of Amazing Accommodative Potential of Technology
  26. 26. SmartIOL
  27. 27. SmartIOL (Formerly SmartLens) (Medennium) • Hydrophobic Acrylic Made Into a Stable 2mm Rod that can be inserted Into the Capsular Bag and Forms a Full-Size Lens • Optic-9.5 by 3.5-mm – Same as Human Crystalline Lens
  28. 28. SmartIOL • Difficult to Determine How Much Gel to Inject to Predictably Control Resulting Lens Power. • Capsulorhexis Must Be Small, So That It Can Be Sealed to Confine the Gel. This May Require New Surgical Technologies. • Control Needed to Get the Critical Optical Interface in the Central Location of the Capsulorhexis • To Minimize Energy Consumption in Accommodation the Intracapsular Pressure Built Up By Lens Epithelial Cells has to be Restored By the Refill Procedure. Only Then Can the Exchange of Potential Elastic Energy Between the Lens Capsule and the Lens Matter Work. (Haefliger, E., Binningen, Switzerland)
  29. 29. The Fluid Lens (PowerVision) • Redistributes Peripheral Fluid Centrally on Accommodation Increasing the Plus Power of the Optic
  30. 30. • Drives Fluid of a Polymer-Matched Refractive Index From the IOLs Soft Haptics Thru Channels to a Fluid-Driven Activator • Causes an Accommodative Increase in the Anterior Curvature of the Lens • Curvature Change Has Been Shown to be As High as 8D • 6 Month Study on 30 Eyes Showed 5D Max
  31. 31. Quest Vision (AMO) • Has Myopic Configuration in the Resting State and an Anterior Position in the Accommodative State
  32. 32. Electro-Active Accommodating IOL (Elenza – Roanoke, VA) • Switchable Liquid Crystal Diffractive Lens • Electrical Control of the Refractive Index of a Nematic Liquid Crystal Sandwiched Between A Photolithographically Defined Transparent Electrode • Hydrophobic IOL with Hermetically Sealed Circuitry • Microsensors Detect Physiologic Changes in Light Triggered by Accommodative Effort • Lithium Ion Power Cells Charged Weekly by an Inductive Charging Element
  33. 33. LiquiLens Vision Solutions Technologies
  34. 34. LiquiLens • Bi-Fluidic IOL • Gravity Based Mechanism Shifts Focal Plane on DownGaze by Altering Interplay of Fluids Against One Another • Capable of Providing Any Desired Spectacle Plane Addition • Prototype Investigations Demonstrated 20D IOL Providing 13 Additional Diopters on Downgaze • Can Be Designed With Any Desired Accommodation, from +1.00 D to +40 D • Action Independent of Ciliary Mechanism
  35. 35. LiquiLens Challenges in Presbyopia • Too Powerful for Young Presbyopes • No Mid-Range (Computer) Vision • Large Incision Required Currently
  36. 36. Multifocali ty Mean Accomodative Amplitude (D) Equivalent Add at Spectacle Plane (D) LiquiLens Bifocal As Desired As Desired Crystalens Multifocal 1.79 Approx. 1.00 Incision Size (mm) Dependence on Ciliary Mechanism 6-7 None 4.5 3.5 Total ICU Multifocal 1.7-1.9 Approx. 1.00 5.5 3.5-3.7 Total NuLens Multifocal 10 Variable ? 5 Total Synchrony Multifocal 2.55 – 3.17 1.50 5.5 3.6 Total ReStor Multifocal Above 4 3.2 6 2.5 None ReZoom Multifocal Above 4 2.75 6 2.5 None SmartIOL Multifocal ? ? 9.5 3 Total Sarfarazi Multifocal 7-8 (animal) ? 5 2-3 Total PowerVision Multifocal ? ? ? ? Total Quest Multifocal ? 3.00 ? ? Total Kellan Tetraflex Multifocal 2.4 1.2 5.75 2.5 Total Akkomodative Optic Diameter (mm)
  37. 37. Other Experimental Technologies in Development • • • • • • • • • • Aspheric Multifocal M-Flex Lens Asymmetric Diffactive Twin-Set IOL Binderflex Lens Design (sulcus) designed to transmit the contractions of the ciliary body directly onto the IOL in order to eliminate negative effects of the shrinking capsular bag on the accommodation process Presbyopic Ablation Corneal Inlay Laser Assisted Sclerectomy PresView Scleral Implants Femtosecond Interlenticular Surgery (Presbyopic Lentotomy) (Gerten, MD, Augenklinik am Neumarkt , Koln, Germany ) Pseudo Accommodative Advanced Surface Ablation PHAKO ERSATZ
  38. 38. Phaco Ersatz (Lens Refilling Surgeries) • Introduced by Julius Kessler in 1966. • Jean-Marie Parel coined the term Phaco Ersatz at Bascom Palmer Eye Institute 1970’s. • Extraction of the lens contents through a sub-1 mm mini-rhexis • Silicon polymers have been shown to have the adequate biocompatibility and optical properties to restore accommodation in monkeys. • Current efforts involve the development of safer polymers that can be cured in situ after lens refilling and avoiding the need of UV light. (Light Adjustable IOLs) • PCO prevention remains a major hurdle • Research is required for practical purposes as deciding the precise amount of refilling required. (Barraquer, R, Institut Universitari Barraquer, Barcelona, Spain)