1. Intraocular Lenses
Doğan Gidon

2. Overview Biological Challange The Eye and Cataracts
Restrictions and Design Constraints
Materials
Polymeric: PMMA, Silicone, Polyacrylic
Ocular Problems
Accomodation
Surgical and Biological Problems
Capsule Opacification
Light Adjusting Lenses

3. The Eye
Lens comes within the capule, divides anterior and posterior chambers – keeps two bodies separate

4. Cataracts Biological lens is useless – opacification
Removal of the lens (and possibly capsule)
Hard to correct vision post-lens removal
Thick spectacles – magnification of image
Problems with single eye cataracts
Poor vision restoration
Solution – Intraocular Lens (IOLs)
Patel, A. S. (2004). Intraocular Implants: A Scientific Perspective. In B. D. Ratner, Biomaterials Science (pp ). San Diego: Elsevier Academic Press.

5. Constraints on the Lens
Mimicking the natural lens
The lens should be
Transparent
Durable over extended periods of time
Non-reactive (biocompatible)
Flexible (vs Rigid)
Fixed (or controlled motion)
Processable (proper curvature)
Non adhesive for cells and bacteria (hydrophobic or low water content)
Able to restore vision (and correct preexisting refractive problems)
Able to withstand optical traumas (eye rubbing etc.)
UV blocking (restore biological visual spectrum)
Polymeric Materials!

6. Constraints on the Eye
Minimal eye disturbance – small incisions overcoming two boundaries
Better delivery systems and smart materials
Minimal physical contact with the lens – mechanical disturbance
Location of the IOL
Low and non-disturbing reaction
Prevention of opacification
Surgical constraints
State of the biological lens, lens capsule and adjacent bodies

7. IOL Design – Location, Location, Location
Where to put the IOL?
Phakic eye: Eye with biological lens
Aphakic eye: Eye with removed biological lens
Pseudophakic eye: Eye with implanted IOL
IOLs can be used on phakic and aphackic eyes
State of the capsule is important and changes design
No capsular bag:
Posterior chamber fixation to ciliary body
IOL placement with Capsular bag intact
Patel, A. S. (2004). Intraocular Implants: A Scientific Perspective. In B. D. Ratner, Biomaterials Science (pp ). San Diego: Elsevier Academic Press.

8. IOL Design Shape Haptic – The supporting extensions on the lens
Optic – the polymeric refractive material that constitutes the lens
Available in singe piece of three piece designs – fixation location and material properties determine the structure
Patel, A. S. (2004). Intraocular Implants: A Scientific Perspective. In B. D. Ratner, Biomaterials Science (pp ). San Diego: Elsevier Academic Press.

9. IOL materials PMMA First IOLs Rigid Delivery problem
large incision (about 6mm) => surgical astigmatism
Available in single piece design
Good fixation
Cheap
Poor biocompatibility – more incidences of postoperative reactions
Surface treatment for better performance
Chehade, M. (1997). lntraocular lens materials and styles: A review. Australian and New Zealand Journal of Ophthalmology (25),
Werner, L. (2008). Biocompatibility of intraocular lens materials. Current Opinion in Ophthalmology (19),

10. IOL materials Foldable Hydrophobic Polyacrylates
Different copolymer acrylics
AcrylSof: Copolymer of Phenylethy acrylate and phenylethyl methacrlyate
Flexible
Smaller surgical incision – foldable/injectable
Weaker then PMMA
Available in three piece and single piece design
Widely used
Chehade, M. (1997). lntraocular lens materials and styles: A review. Australian and New Zealand Journal of Ophthalmology (25),
Werner, L. (2008). Biocompatibility of intraocular lens materials. Current Opinion in Ophthalmology (19),

11. IOL materials Hydrophilic hydrogels Silicone
Poly(HEMA) copolymerized with acrylic monomers
Not widely used due to post operative complications
Silicone
Materials such as poly(dimethyl siloxane)
Foldable and soft
Can only support plate haptics
Controversial data on post operative complications
Chehade, M. (1997). lntraocular lens materials and styles: A review. Australian and New Zealand Journal of Ophthalmology (25),
Werner, L. (2008). Biocompatibility of intraocular lens materials. Current Opinion in Ophthalmology (19),

12. Comparison
Chehade, M. (1997). lntraocular lens materials and styles: A review. Australian and New Zealand Journal of Ophthalmology (25),

13. Ocular Problems
The biological lens changes shape to accommodate far and near images
Property removed with introduction of IOLs
Spectacle dependence
Challenge to restore visual accommodation
Monovision: differential correction of the two eyes – one near one far adjusted
High patient variability in results
Menapace, R. (2007). Accommodating intraocular lenses: a critical review of present and future concepts . Graefe’s Arch Clin Exp Ophthalmol (245), 473–489

14. Multifocal IOLs Multiple Foci on the lens
Simultaneous distance and far correction
Two superimposed images one in focus and one out of focus
Reported discomfort in patients
Halos especially at night
decreased contrast sensitivity due to light distribution
Reported increased spectacle independence
Expectation management lead to increased satisfaction – high patient variability
Bellucci, R. (2005). Multifocal intraocular lenses. Current Opinion in Ophthalmology (16), 33–37.

15. Multifocal IOLs
Bellucci, R. (2005). Multifocal intraocular lenses. Current Opinion in Ophthalmology (16), 33–37.

16. Accommodating IOLs
Aim for true restoration of accommodation through active or passive movement or shape change of the lens with external stimuli
Designed to respond to ciliary muscle contraction
Contradictory results – studies found them to be statistically not better than existing designs
Company led studies criticized for methodology errors
Capsular fibrosis – decreases elasticity and function
High patient variability
Doane, J. F. (2004). Accommodating intraocular lenses. Current Opinion in Ophthalmology (15),

17. Accommodating IOLs
Doane, J. F. (2004). Accommodating intraocular lenses. Current Opinion in Ophthalmology (15),

18. Accommodating IOLs Active responsive systems Mostly conceptual
Magnet driven
Two lens systems (Dual optic)
Smart Lenses – Lens refilling
Temperature responsive hydrogel to fill the lens capsule
Mostly conceptual
Poor clinical results
High foreign body reaction – not very biocompatible
Doane, J. F. (2004). Accommodating intraocular lenses. Current Opinion in Ophthalmology (15),

19. Accommodating IOLs
Doane, J. F. (2004). Accommodating intraocular lenses. Current Opinion in Ophthalmology (15),

20. Accommodating IOLs
Doane, J. F. (2004). Accommodating intraocular lenses. Current Opinion in Ophthalmology (15),

21. Surgical and Biological Problems
Posterior Capsule Opacification
Migration of Lens Epithelial Cells (LECs)
Proliferation and differentiation of LECs to pearls or fibroblastic cells
Most common problem – secondary cataract
Geometry and material are important
Hydrophobic acrylic < silicone < PMMA
Adhesion of capsule to the lens – no space no cells
Square edged lenses prevent cell migration
Single piece lenses perform better – no secondary interface
Treated with Nd: YAG Laser capsulectomy
Werner, L. (2008). Biocompatibility of intraocular lens materials. Current Opinion in Ophthalmology (19), 41-49
Hollick, E. J. (1998). Lens epithelial cell regression on the posterior capsule with diVerent intraocular lens materials . Br J Ophthalmol (82), 1182–1188. .

22. Surgical and Biological Problems
Anterior Capsule Opacification
Problem for accomodating IOLs
Contact with anterior capsule
Problem esp. with silicone
Interlenticular Opacifiation
Dual optic systems
Problem for accomodationg IOLs
Werner, L. (2008). Biocompatibility of intraocular lens materials. Current Opinion in Ophthalmology (19), 41-49

23. Surgical and Biological Problems
Bacterial Contamination and infection
Esp. with polypropylene haptics
Lens malposition
Asymmetric capsulorhexis
Surgical skill
Lens detachment
Pigment dispersion
Anterior implants – Iris contact
Corneal disruption
Carlson, A. N. (1998). Intraocular Lens Complications Requiring Removal or Exchange . Survey of Ophtalmology , 42 (4),

24. Light Adjustable IOLs (LALs)
Silicone based IOLs (also polyacrylic prototype)
Implanted not completely polymerized
UV Photo polymerization in situ to change the shape and power and character of the lens (inc. toric or multifocal)
Creating a gradient and provoke diffusion
Development of a light delivery device for precise manipulation
Precise power adjustment for complex situations– esp for patients who underwent refractive laser surgery
Allows trial periods for monovision or bifocal type IOLs
Maloney, R. (2003, Jan). The Changing Shape of Customized IOLs. Review of Ophtalmology ,
Schwartz, D. M. (2003;). Light-Adjustable Lens. Trans Am Ophthalmol Soc (101),

25. Light Adjustable IOLs (LALs)
Maloney, R. (2003, Jan). The Changing Shape of Customized IOLs. Review of Ophtalmology ,

26. Conclusion Positive outcome is dependent on Patient Surgical skill
Managed expectations
appropriate IOL selection for situation
Surgical skill
Small incisions
No bacterial contamination or malposition
IOL material
Preventive of PCO
Novel materials to improve spectacle independence and restore natural visual acuty

27. Questions?