الفهرس 
Rigid PMMA intraocular lensesOnly 14 pages are availabe for public view
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Abstract
IOL design has developed through the years passing through several generations and has now become extremely successful with very few complications (Alego, and William, 2009).
More recently, the majority of effort and funding appears to be spent on the development of complex foldable IOLs that not only restore the refractive power of the eye after cataract extraction through small incisions, but also provide some special features that include multifocality, toric corrections, pseudoaccommodation, and postoperative adjustment of the IOL refractive power (Hanas, 2009).
Intraocular lenses (IOLs) classified based on the biomaterials (polymers) used for the manufacture of IOL optics into two major groups, namely rigid and foldable:
II- Rigid, manufactured from polymethyl methacrylate (PMMA)
II- Foldable, manufactured from
1- Silicone,
2- HyDROPhobic soft acrylic materials,
3- HyDROPhilic acrylics also known as hydrogels.
III- Specialized foldable intraocular lenses include:
- Aspheric intraocular lenses.
- Multifocal intraocular lenses.
- Accommodative intraocular lenses.
- Toric intraocular lenses.
- Blue light-filtering intraocular lenses.
- Phakic intraocular lenses (Kohnen, and Koch, 2006, Ashok et al., 2005).
I- Rigid intraocular lenses
Advantages
- Long term experience
- Good biocompatibility
- Cheap
Disadvantages
- Rigid so need large incision
- Pits with YAG laser
- High incidence of PCO
II- Foldable, manufactured from
1- Silicone,
2- HyDROPhobic soft acrylic materials,
3- HyDROPhilic acrylics also known as hydrogels.
1- Silicone IOLs
Advantages
- Foldable - small incision
- Fairly low incidence of PCO (particularly second generation silicone)
Disadvantages
- Low refractive index - thicker IOLs (first generation silicone)
- High refractive index - thinner IOLs (second generation silicone)
- Pits with YAG laser
- Rapid unfolding in the eye
- Dislocation after YAG
- More decentration
2- HyDROPhobic soft acrylic intraocular lenses
Advantages
- Foldable - small incision
- High refractive index - thin IOLs
- Very low incidence of PCO
- Biocompatible
- Fewer pits with YAG laser
- Slow controlled unfolding
Disadvantages
- Short experience
- Tacky surface - sticks to forceps
- More difficult to fold
- Glistening and glare
3- HyDROPhilic acrylic intraocular lenses (Hydrogel)
Advantages
- Foldable - small incision
- Good biocompatibility
- low inflammatory cell reaction
- Fewer pits with YAG lase
- Controlled unfolding
- Less endothelial cell damage with cornea touch
Disadvantages
- LECs on anterior IOL surface
- High incidence of PCO
III- Specialized foldable intraocular lenses include:
1- Aspheric IOLs
Some studies show clear improvements in functional vision with aspheric lenses but a number have found little or no difference as measured by contrast sensitivity or subjective preference.
Three aspheric IOLs have currently been approved by the Food and Drug Administration (FDA) for the correction of spherical aberration:
1- The Tecnis
2- The AcrySof IQ
3- The Sofport L161AO
3 other types are available in Europe
1- Acri.Smart 46LC
2- Akreos AO
3- Hoya VA60BB
2- Multifocal IOLs
Multifocal IOLs have two or more optical foci. This means the presence of at least two co-axial dioptric powers, usually separated by a 4 D interval to provide a 3 D interval at the spectacle plane.
On the retina, the two dioptric powers will produce two superimposed images of any observed object. Under the best conditions, one image will be in sharp focus, and the other image will be blurred by a 3 D defocus aberration
3- Accommodative IOLs
The so-called accommodative intraocular lenses are made of flexible silicone or acrylate, and have in common a thin and flexible “hinge” at the haptic–optic junction which should allow forward movement of the optic with haptic compression