Glossary of Terms
Aphakia — The absence of the eye's natural crystalline lens usually after cataract removal.
Aphakic Spectacles — Thick eyeglasses that were once the standard correction for optical power following the extraction of a cataract. The glasses were considered cumbersome and greatly distorted peripheral vision. Today, an intraocular lens (IOL) is implanted in the eye after the cataract is removed.
Cornea — Commonly known as the "window of the eye," it is the clear, curved covering over the iris and pupil.
Extracapsular Cataract Extraction Technique — Extracapsular cataract extraction (ECCE) is a category of eye surgery in which the lens of the eye is removed while the elastic capsule that covers the lens is left partially intact to allow implantation of an intraocular lens (IOL). This approach is contrasted with intracapsular cataract extraction (ICCE), an older procedure in which the surgeon removed the complete lens within its capsule and left the eye aphakic (without a lens). The patient's vision was corrected after intracapsular extraction by extremely thick eyeglasses or by contact lenses.
There are two major types of ECCE: manual expression, in which the lens is removed through an incision made in the cornea or the sclera of the eye; and phacoemulsification, in which the lens is broken into fragments inside the capsule by ultrasound energy and removed by aspiration.
Small Incision Cataract Surgery (SICS) is a form of ECCE that facilitates better visual results, lower costs, and increased effiency. Using the extracapsular cataract extraction technique, the surgeon makes an incision where the cornea and sclera meet. Carefully entering the eye through the incision, the surgeon gently opens the front of the capsule and removes the hard center, or nucleus, of the lens. Using a microscopic instrument, the surgeon then suctions out the soft lens cortex, leaving the capsule in place.
Glaucoma — An eye disease in which the optic nerve is slowly damaged by pressure within the eye. If untreated, can result in progressive loss of vision. Known as the "silent thief" of sight, an individual can have glaucoma and not realize it until it is too late. The best prevention is regular check-ups by an ophthalmologist. A family history of glaucoma can increase the risk of occurrence.
Intracapsular Cataract Extraction — a form of cataract surgery developed in the early 1980s, but seldom used today because more advanced techniques are available. In this surgery, the entire natural lens of the eye, including the capsule that holds it in place, is removed. The procedure requires a much larger incision than used in the more recently developed techniques.
Intraocular Lens (IOL) — IOL is a clear plastic lens that is then implanted in the eye during the cataract operation. Lens implants have certain advantages. They usually eliminate or minimize the problems with image size, side vision and depth perception noted by people who wear cataract eyeglasses. They are also more convenient because they remain in the eye and do not have to be removed, cleaned, and reinserted as do contact lenses, a huge consideration in the developing world.
Iris — The colored part of the eye which acts like a "window shade" enlarging or diminishing the size of the pupil to let in the proper amount of light.
Ophthalmology — The branch of medicine that deals with the anatomy, functions, pathology and treatment of the eye.
Presbyopia — Also called "old age vision," occurs as the lens of the eye ages and becomes less elastic. Usually this becomes significant after age 45 and is often signaled by the need for bifocals.
Retina — The membrane at the back of the eye which contains millions of tiny light-sensitive receptors (rods and cones) that transmit sensations to the optic nerve, which, in turn, transmits images to the brain for interpretation.
Zonule — Zonules are responsible for holding the lens of the eye. Ciliary zonules are a series of fibers connecting the ciliary body and lens of the eye, holding the lens in place. Also called Zinn nodule.