They are notorious for their negative impact on the corneal endothelial lining, which is vital for maintaining a healthy clear cornea. Iris-fixated PIOLs, attached by claws to the mid-peripheral iris by a technique called enclavation. It is believed to have a lesser effect on corneal endothelium. The main complication with this type is their tendency to cause endothelial cell reduction. Sulcus-supported PIOLs, placed in the posterior chamber in front of the natural crystalline lens. This type of PIOLs is gaining more and more popularity. They have special vaulting so as not to be in contact with the normal lens. The main complication with older versions was a small possibility of cataract formation. Blue-light filtering IOLs
Blue light filtering IOLs filter the UV and high-energy blue light present in natural and artificial light, both of which can cause vision problems; however too much filtering of blue light can increase depression, especially in the winter months (SAD). The trademarked "Natural Yellow" material is available in three hydrophilic IOLs. Dr. Patrick H. Benz of Benz Research and Development created the first IOL material to incorporate the same UV-A blocking and violet light filtering chromophore thats present in the human crystalline lens in order to attempt to protect the retina after cataract extraction of the natural crystalline lens. A Cochrane Review found little evidence of important differences between blue‐light filtering and non‐blue‐light filtering lenses for protecting the macula (back of the eye) after cataract surgery. This was due to studies being too small and too short‐term to provide reliable results.
However, it can be a problem for patients that are not yet presbyopic (or are in the early stages of presbyopia) undergoing refractive lens exchange for the sake of correcting refractive errors. Monovision, in which one eye is made emmetropic and the other myopic, can partially compensate for the loss of accommodation and enable clear vision at multiple distances. More versatile types of lenses (multifocal and accommodating IOLs) were introduced in 2003 in the United States, with the approval by the Food and Drug Administration. These come at an additional cost to the recipient beyond what Medicare will pay and each has advantages and disadvantages. Multifocal
Multifocal IOLs attempt to provide simultaneous viewing of distance vision and near vision. Trifocal IOLs can provide intermediate vision. Many multifocal IOL designs attempt to achieve this simultaneous viewing focus using a concentric ring design, which alternates distance and near focal points. However, many concentric ring multifocal lenses used today are prone to glare and mildly compromised focus at all ranges of vision. People who have a multifocal IOL after their cataract is removed may be less likely to need additional glasses compared with people who have standard monofocal lenses. However, people receiving multifocal lenses may experience more visual problems than with monofocal lenses. The most common adverse visual effects from multifocal IOLs include glare, halos (rings around lights), and a loss of contrast sensitivity in low-light conditions. Adjustable Lens
An adjustable IOL is unlike any other lens as its prescription power can be adjusted after surgery once all healing is complete.