Types of Intraocular Lenses
During cataract surgery the natural lens of the eye is replaced with a clear synthetic lens. These “intraocular lenses” (or “IOLs”) come in a dizzying array of powers, shapes, and materials. The power of the IOL is generally determined based on eye measurements made prior to cataract surgery. The shape and material of the IOL are often chosen based on the visual needs of the patient as well as the preference of the surgeon.
Monofocal Intraocular Lenses
Anyone who has cataract surgery and chooses to have the intraocular lens (IOL) covered by Medicare or insurance will have a monofocal IOL implanted in the eye. These lenses are clear and will often result in better vision with or without spectacles after surgery. However, most people who choose this IOL will still need to wear glasses most (if not all) of the time. These IOLs can be made of acrylic, silicon, or other material.
The following intraocular lenses (IOLs) fall within the class of “premium”, “refractive” or “presbyopia-correcting” IOLs. Most of these lenses and the surgeon’s fee to implant them are not covered by Medicare or Insurance.
Astigmatism-Correcting (Toric) Intraocular Lens
Astigmatism is most often caused by an irregular corneal surface. It results in blurred vision without glasses. One of the methods of correcting astigmatism during cataract surgery is to use a “toric” intraocular lens (IOL). These are essentially monofocal IOLs that also correct astigmatism. Currently all toric IOLs available in the USA are made of either acrylic or silicon.
Multifocal Intraocular Lenses
Intraocular lenses (IOLs) that focus both distance and near objects onto the retina at the same time are called “multifocal” IOLs. Although these IOLs can provide a nice range of vision without the use of glasses after cataract surgery, they do have some limitations. First, they are not appropriate for someone who has significant dry eye or other eye disease such as glaucoma, macular degeneration, or diabetic retinopathy. Second, they do result in rings around point sources of light at night.
Pseudo-accommodating Intraocular Lenses
When we are young our natural lens can change shape inside the eye. This allows us to focus both on distant as well as near objects. This natural ability to change focus is called “accommodation.” When synthetic intraocular lenses (IOLs) provide a range of vision after cataract surgery they are called “pseudo-accommodating” IOLs. These IOLs can be made of silicon, acrylic, or Collamer®.