Treatment of Cataracts

Surgery

The standard cataract surgical procedure is typically performed in either a hospital or in an ambulatory surgery center. The most common form of cataract surgery today is a process calledphacoemulsification. With the use of an operating microscope, your surgeon will make a very small incision in the surface of the eye in or near the cornea. A thin ultrasound probe is inserted into the eye that uses ultrasonic vibrations to dissolve (phacoemulsify) the clouded lens. These tiny fragmented pieces are then suctioned out through the same ultrasound probe. Once the cataract is removed, an artificial lens is placed into the same thin capsular bag that the cataract occupied. Thisintraocular lens is essential to help your eye focus after surgery.
There are three basic techniques for cataract surgery:

• Phacoemulsification: This is the most common form of cataract removal as explained above. In this most modern method, cataract surgery can usually be performed in less than 30 minutes and usually requires only minimal sedation and numbing drops, no stitches to close the wound, and no eye patch after surgery.

• Extracapsular cataract surgery: This procedure is used mainly for very advanced cataracts where the lens is too dense to dissolve into fragments (phacoemulsify) or in facilities that do not have phacoemulsification technology. This technique requires a larger incision so that the cataract can be removed in one piece without being fragmented inside the eye. An artificial lens is placed in the same capsular bag as with the phacoemulsification technique. This surgical technique requires a various number of sutures to close the larger wound, and visual recovery is often slower. Extracapsular cataract extraction usually requires an injection of numbing medication around the eye and an eye patch after surgery.

Intracapsular cataract surgery: This surgical technique requires an even larger wound than extracapsular surgery, and the surgeon removes the entire lens and the surrounding capsule together. This technique requires the intraocular lens to be placed in a different location, in front of the iris. This method is rarely used today but can be still be useful in cases of significant trauma.

Small Incision Cataract Surgery

In a newer surgical method, called small-incision (no-stitch) cataract surgery, the nucleus is broken up (emulsified) by an ultrasound probe. No-stitch surgery requires only a single, 1/8-inch incision. A small incision means faster healing. Redness and inflammation of the eye disappear in two to three weeks with small-incision surgery, vs. six to eight weeks with extracapsular extraction. A special advantage of small-incision surgery is that it is less likely to cause astigmatism. This is blurred vision that results when tension on the stitches distorts the cornea. Small-incision surgery involves an incision not on the cornea, but on the less sensitive sclera (the white of the eye).
Because of its advantages, many eye surgeons have adopted the no-stitch technique. Others feel strongly that extracapsular surgery is just as good. But after the eye heals completely, there is generally little difference between the results from extracapsular and small-incision surgery. A patient may not be a candidate for the no-stitch method, in that advanced cataracts tend to be too hard to emulsify easily. In such cases, extracapsular surgery may be the better choice.
In the past, people who underwent cataract surgery had to wear thick "Coke bottle" eyeglasses. Now, immediately after the removal of the cataract, the surgeon implants a plastic lens directly into the space left by the removal of the clouded lens. This intraocular implant helps the cornea focus light onto the retina to give a clear image.
There are many different implants on the market and they fall into two general categories, based on their location in the eye:
Posterior chamber implants, the more popular type, are placed behind the iris, occupying the exact position of the original lens. There are now smaller oval and foldable lenses that can be used with small-incision surgery.
Anterior chamber implants are inserted into the fluid-filled space between the iris and the cornea.
Some experts estimate that about 88 of every 100 persons receiving IOLs (intraocular lenses) will achieve 20/40 vision or better. (An individual with 20/40 vision can read letters on an eye chart from 20 feet away. While a person with normal 20/20 vision can read the chart from 40 feet away, 20/40 vision is good enough to get a driver's license in most states.) Among those who do not have other eye diseases, about 94 of 100 will achieve 20/40 vision.
What are the different types of intraocular lenses implanted after cataract surgery?

• As the natural lens plays a vital role in focusing light for clear vision, artificial-lens implantation at the time of cataract surgery is necessary to yield the best visual results. Because the implant is placed in or near the original position of the removed natural lens, vision can be restored, andperipheral vision, depth perception, and image size should not be affected. Artificial lenses are intended to remain permanently in place, require no maintenance or handling, and are neither felt by the patient nor noticed by others.

There are a variety of intraocular lens styles available for implantation, including monofocal, toric, and multifocal intraocular lenses.

• 1. Monofocal lens: These lenses are the most commonly implanted lenses today. They have equal power in all regions of the lens and can provide high-quality vision at a single focal point (usually at distance). They usually require only a light pair of spectacles for optimal distance vision correction. However, monofocal lenses do not correct astigmatism, an irregular oblong corneal shape that can distort vision at all distances, and require corrective lenses for all near tasks, such as reading or writing.

2. Toric lens: Toric lenses have more power in one specific region in the lens (similar to spectacles with astigmatism correction in them) to correct astigmatism, which can further improve unaided distance vision for many individuals. Due to the difference in lens power in different areas, the correction of astigmatism with a toric lens requires that the lens be positioned in a very specific configuration. While toric lenses can improve distance vision and astigmatism, they still require corrective lenses for all near tasks, such as reading or writing.

3. Multifocal lens: Multifocal intraocular lenses have a variety of regions with different power within the lens that allows individuals to see at a variety of distances, including distance, intermediate, and near. While promising, multifocal lenses are not for everyone. They can cause significantly more glare than monofocal or toric lenses. Further, multifocal lenses cannot correct astigmatism, and some patients require additional surgery such as LASIK to correct astigmatism and maximize their unaided vision.