Extra-capsular Cataract Extraction
Extra-capsular cataract extraction is a method for surgically removing a cataract, a clouding of the eye's naturally clear lens.
A cloudy lens interferes with light passing through to the retina, the light-sensing layer of cells at the back of the eye. A cataract can be compared to looking at the world through a foggy window. In extra-capsular extraction, an incision is made in the side of the cornea at the point where the cornea and sclera, the white part of the eye, meet. Carefully entering the eye through the incision, the surgeon gently opens the front of the lens capsule and removes the lens's hard center or nucleus. The soft lens cortex is then suctioned out, leaving the back of the capsule in place. An incision requiring sutures is necessary because the lens is removed in one piece. A plastic implant called an intraocular lens, or IOL, is substituted for the original lens. The implanted IOL allows light to be focused on the retina. The sutures may be removed for up to six weeks, and best-corrected vision is achieved. During recovery, avoiding bending over or lifting heavy objects may be necessary.
Causes of Cataract
The cause of most cataracts is unknown, but they are usually related to the aging process. As one age, the chance of developing cataracts increases. Other causes include a family history of cataracts, inflammation within the eye, prolonged exposure to the sun's ultraviolet ("UV") rays, eye injuries (trauma), medical problems such as diabetes and kidney diseases, and long-term use of some medicated eye drops, such as steroids. Children and newborn infants can also develop cataracts.
Symptoms of Cataract
The common symptoms of cataracts include:
- Gradual blurring of vision: one eye appears to be more transparent and brighter than the other
- Colors appear dull, particularly greens and blues
- Glare and light sensitivity
- Double vision or "Ghosting"
- Objects may appear yellow, hazy, blurred, or distorted
- The need for brighter light to read
- Poor night vision and Halo effects around bright lights at night, eg, car headlights and street lamps
- Frequent need to change lens prescription
Cataract Surgery
In a cataract operation, the eye's natural lens is removed. Therefore, a new lens must replace the one removed to restore vision. This new lens can be used in special eyeglasses with thick lenses or contact lenses. Most commonly, it is an intraocular lens implant, which permanently replaces the old lens.
The artificial lens is made of plastic and is usually inserted when the cataract is removed. Depending on the individual case, the lens is placed directly behind or, less frequently, in front of the iris, the "colored" part of the eye. Not every case is appropriate for this type of procedure, and the method of implantation used depends on the individual patient.
Once the surgeon determines an appropriate intraocular lens replacement, the patient undergoes a special preoperative evaluation. Like contact lenses and "prescription" eyeglasses, intraocular lenses differ in refractive power, and the assessment will determine the proper lens power of the implant. The length of the eye is measured, and the cornea's curvature is evaluated. The implant power is calculated based on this information and performed on a computer.
The natural lens can accommodate or change shape so that it is possible to focus at varying distances. The intraocular lens, which cannot change shape, is usually calculated for a middle distance so that the patient can see well enough to move about without glasses. Standard eyeglasses must still be worn to see up close-ups and far away. In most cases, though, patients notice significant improvements in vision resulting from intraocular lens implantation.
Surgery Type
Cataract surgery removes the cloudy lens, which usually takes 30 minutes and is performed on an outpatient basis. There are presently two (2) common types of Cataract Surgery:
- Conventional Cataract Surgery: Extra-capsular Cataract Extraction or ECCE
- Modern Cataract Surgery: Phacoemulsification or Phaco
The comparisons of these surgical types are as follows:
