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During cataract surgery the clouded lens of the eye is removed and replaced with a clear artificial lens. In order to perform this surgery an opening must be created by an ophthalmic surgeon, called a cataract incision. It is made on the side of the cornea and is used for the removal of the cataract and the insertion of the new lens.
The size of the cataract incision is usually determined by the ophthalmologist prior to surgery. The different types of incisions used for cataract surgery generally range in size from approximately 0.078 inches (2 mm) to 0.472 inches (12 mm). Determining the appropriate incision size depends on several factors, such as the cataract itself, the removal technique and the type of material used in the replacement lens.
Cataracts are usually removed using a procedure called phacoemulsification. This method uses an instrument that breaks up and then sucks the cataract out of the eye. When performing this particular form of cataract surgery, an extremely small incision that is typically 0.118 inches (3mm) or less is made. This is generally large enough to allow the instrument and the replacement lens into the eye.
Breaking up the cataract for removal may not be an option in some cases, particularly if it is an older or more dense cataract. In these situations, a procedure called Extracapsular Cataract Extraction (ECCE) is performed. To perform an ECCE, the surgeon will need to create a cataract incision that is up to 0.472 inches (12 mm). An incision of this size allows the surgeon to remove the entire cataract.
The material of the replacement lens is also a determining factor when it comes to the cataract incision. There are three types of lenses that ophthalmologists will typically use: silicone, acrylic or a lens made from a material called polymethylmethacrylate (PMMA). Both the acrylic and silicone lenses can be folded and may be inserted through a very small cataract incision, like the incision used for phacoemulsification. A PMMA lens does not fold and requires a larger incision in order to insert it into the eye.
Following surgery, the cataract incision may or may not require sutures. Very small incisions are often self-sealing and are left to close on their own. Larger cataract incisions often require the use of sutures to close the wound and are removed at a later date.