What follows is a verbal description of the critical elements in modern cataract surgery. In the future I will be posting diagrams, and video clips of each step. Each topic is discussed in the order that they occur during surgery.
The advantages of Topical Anesthesia are numerous. Most importantly, you are spared the pain and risks involved with the injection, plus the operative results are much faster, and sometimes immediate. I have literally had patients tell me they could see better as soon as I pulled away the operating microscope! After Topical Anesthesia, you go home without an eye patch. Also, when combined with a Clear Corneal Incision you do not have to stop taking blood thinners (such as coumardin and aspirin).
The disadvantages to Topical Anesthesia are technical in nature. Basically the surgeon must employ many of the the latest advances in cataract surgery in order to pull it off, including the use of a "Clear Corneal Incision" and a "Foldable Implant." Personally I have found that these advances have simplified cataract surgery, but learning the necessary techniques wasn't easy. At present, only the more highly skilled and confident surgeons have learned to use Topical Anesthesia.
The use of topical anesthesia eliminates the need for a painful injection, and it also allows patients to leave the operating room without even a patch.
Yes, even the most modern techniques in cataract surgery require that an incision be made in the eye. No, cataract surgery cannot be performed with lasers (a common misconception; so called "secondary cataracts" can be treated with laser, but secondary cataracts only occur in eyes that have already had cataract surgery).
Over the past 20 years or so, incision size has come down from 16, to 12 to less than 3 millimeters in length. With the very small incisions used today, the preferred location of the incision has also changed. It is now possible to make micro-incisions in the temporal clear cornea, rather than the superior, sub-conjunctival, or "scleral-tunnel" approach. The principle advantages to temporal, clear-corneal incisions are: (1) they induce very little trauma, and therefore heal faster; (2) the cornea can be completely anesthetized with drops only, thereby facilitating topical anesthesia; and (3) they are easier to make, and safer to use for both the patient and the surgeon. I am not aware of any substantial disadvantage to the temporal, clear-corneal incision.
Because this type of incision is so small, it does not require a stitch to close it.
Phacoemulsification or Phaco is the modern method for removing cataracts utilizing high energy ultrasound. Using this technology, a cataract which measures 12 millimeters in diameter and 4 millimeters in thickness can be vacuumed through an incision which measures only 3 millimeter or less! Basically, phaco uses a hollow needle which, when activated by the surgeon, vibrates at 40,000 times per second thereby emulsifying the cataract. Emulsified cataract is aspirated through the hollow center in the phaco needle, and fluid is simultaneously infused into the eye in order to keep it "inflated" during surgery. Cataracts CANNOT be removed by laser.
The final step in cataract surgery is lens implantation. Prior to the development of safe intra-ocular lens implants, anyone who had their cataracts removed was forced to wear incredibly thick and heavy glasses, or contact lenses to correct their vision to normal. A typical "three piece" lens implant looks like a miniature, round magnifying glass, about 6 millimeters in diameter, with two wiry attachments called haptics. The haptics extend out to a total diameter of about 13 millimeters, and when slightly compressed, they suspend the lens implant inside the lens capsule (which you may recall, has a diameter of only 12 millimeters). Obviously a rigid six millimeter lens, with haptics that extend out to 13 millimeters is not going to fit through a 3 millimeter incision.
Flexible, or foldable lens implants however, can be rolled up into special insertion devices and "injected" through tiny 3 millimeter micro incisions. Once unfolded inside the eye, the wiry haptics suspend the implant inside the same space formerly occupied by the cataract. After a few weeks, the haptics heal into place and further stabilize the implant. "Plate" lens implants are also available. Although made from a single piece of silicone, plate lenses also have haptics, and a central lens or optic. The image above shows a foldable plate lens implant unfolding as it is injected into the eye.
Before cataract surgery, your surgeon makes measurements on the eyes that assist him or her in selecting the correct lens power. Usually the power is selected to optimize your distance vision. In other words, by controlling the power of your implant, your surgeon can correct any pre-existing near-sightedness or far-sightedness.
New implants are now available that can correct astigmatism, or that can simultaneously correct both distance and near vision!