METHODS OF CATARACT REMOVAL
A cataract is the natural lens of the eye that has become clouded. It is this cloudy lens that is removed in cataract surgery.
Cataracts are removed by several different methods. All of these methods are capable of producing good results when used by a surgeon well-trained and experienced in the particular method. The newest technologies, however, are the most desirable and give you the best chance of good distance vision without glasses and are less likely to produce astigmatism.
There are two older methods of cataract surgery which may still be used infrequently.
The oldest method is called the intra capsular technique. It was developed many years ago with the invention of refrigeration. It involves the use of controlled cooling of a very fine probe in the shape of a blunt needle. This probe is placed on the cataractous lens and frozen to it. The lens is then lifted out of the eye through a large, 11-13 millimeter corneal incision which is then closed with many sutures. This large incision with sutures caused astigmatism which could be corrected only with glasses. The distortion of vision by astigmatic glasses can be a problem for those people with large amounts of astigmatism.
The next surgical step forward was extracapsular cataract extraction by nuclear expression, called ECCE (extracapsular cataract extraction). It does not require freezing the lens to a fine probe.
The center hard part of the cataract is forced out of a large 11-13 millimeter incision like the center of a wet jellybean squished between your fingers. This procedure, like the first one, also causes astigmatism because of the large number of sutures required. Despite cutting sutures two to three months after surgery, wound creep (slippage) occurs one to three years after surgery for many people. This results in poor vision without glasses and frustrating vision with glasses due to distortion of the field of vision and blurry vision when looking out of the peripheral part of the glasses, called off axis blur. With these older forms of surgery, astigmatism is a major visual problem.
The newest technique available is called phacoemulsification. As the Greek word for lens is “phakos”, the word phacoemulsification means to emulsify the lens. For simplicity it is often referred to as the suction or ultrasound method, called phaco.
This technique, developed by Dr. Charles Kelman, reduces the incision to a small 3 millimeter (one millimeter is the diameter of the tip of a lead pencil or the thickness of 2 stacked credit cards). Smaller lenses and foldable lenses have been developed that can be placed through this small opening.
This technique uses a sophisticated computer-controlled system connected to an instrument which produces ultrasonic movement at the tip of a blunt needle to reduce the cloudy lens to tiny particles in a semi-liquid form. These particles are then removed from the eye through the very same small tube (blunt needle), somewhat like a microscopic vacuum cleaner.
Advantages of the phacoemulsification method:
1. Because of the small 3 millimeter scleral pocket or clear corneal incision there is little or no induced astigmatism. This results in good distance or near vision without glasses.
2. Small relaxing incisions in the cornea, call astigmatic keratotomy, can be combined with the cataract surgery to correct preexisting astigmatism.3. The small scleral pocket or clear corneal incision makes possible nearly full activity from the first day after surgery. This is because the scleral pocket or clear corneal incision is self sealing.
4. This method helps provide a good way to fasten intraocular lens implant. A small opening in the front surface of the human lens skin (capsule) is made in a circular shape only 5 mm. in diameter. It is called a capsulorhexis.
The lens implant is then placed inside the capsular bag through this opening so that the intraocular lens will end up in the capsular bag. This is done in an attempt to insure that the implant power predicted by the computer is correct for a particular eye. Rarely the computer predicted power of the lens implant does not work and a surprise in the post operative refraction results. In this case an exchange procedure may be necessary.
5. No sutures are needed to close the cataract incision.
6. Most surgeons using this method feel that it reduces the likelihood of some complications which occasionally occur during and following cataract surgery.
A frequently asked questions is, “Do you use the laser method?”
Lasers are used to treat certain eye problems other than cataracts, but there is one research method of removing cataracts with a laser driven phaco. Many people confuse laser with phacoemulsification, probably because laser is an easier word to remember. If you should ever hear of a cataract being removed by laser, you can be virtually certain they really mean phacoemulsification.
Just recently, experimental phaco hand pieces are laser driven, but it is the high frequency vibrations of the tip that emulsify the cataract in the same way as the conventional ultrasound driven phacoemulsifier.