Eye disease - Cataract (2 of 2)

Eye disease - Cataract (2 of 2):

What are the different types of cataract surgery?

The standard cataract surgical procedure is performed in a hospital or in an ambulatory surgery center on an outpatient basis. The most common form of cataract surgery today involves a process called phacoemulsification. With the use of an operating microscope, your surgeon will make a very small incision in the surface of the eye in or near thecornea. A thin ultrasound probe, which is often confused with a laser by patients, is inserted into the eye and 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 thin capsular bag that the cataract previously occupied. This lens is essential to help your eye focus after surgery.

There are three basic techniques for cataract surgery:

1. 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. Numbing eyedrops or an injection around the eye is used and, in general, no stitches are used to close the wound, and often no eye patch is required after surgery.
2. Extracapsular cataract surgery: This procedure is used mainly for very advanced cataracts where the lens is too dense to dissolve into fragments (phacoemulsify). 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.
3. 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 still be useful in cases of significant trauma.

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 as a replacement for the natural lens to yield the best visual results. Because the implant is placed in or near the original position of the removed natural lens, vision is restored, and peripheral vision, depth perception, and image size are not affected. Artificial lenses usually 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 distance vision, usually with only a light pair of spectacles. Monofocal lenses are in sharpest focus at only one distance. They do not correct pre-existing astigmatism, a result of irregular corneal shape that can distort vision at all distances. Your surgeon may correct theastigmatism at the time of cataract surgery by making one or two additional incisions in the periphery of the cornea. This does not make the surgery more dangerous. People with significant astigmatism require corrective lenses for sharpest vision at all distances. Patients who have had monofocal intraocular lenses implanted usually require reading glasses.
2. Toric lens: Toric lenses have more power in one specific region in the lens to correct astigmatism as well as distance vision. 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, the patient still will require corrective lenses for all near tasks, such as reading or writing.
3. Multifocal lens: Multifocal intraocular lenses are one of the latest advancements in lens technology. These lenses have a variety of regions with different power that allows some 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. Multifocal lenses cannot correct astigmatism, and some patients still require spectacles or contact lenses for clearest vision.

What should one expect prior to and on the day of cataract surgery?

Prior to the day of surgery, your ophthalmologist will discuss the steps that will occur during surgery. Your ophthalmologist or a staff member will ask you a variety of questions about your medical history and perform a brief physical exam. You should discuss with your ophthalmologist which, if any, of your routine medications you should avoid prior to surgery. Prior to surgery, several calculations will be made to determine the appropriate power of intraocular lens to implant. A specific artificial lens is chosen based on the length of the eye and the curvature of the cornea (the clear portion of the front of the eye).

It is important to remember to follow all of your preoperative instructions, which will usually include not eating or drinking anything after midnight the day prior to your surgery. As cataract surgery is an outpatient procedure, arrangements should be made with family or friends to transport you home after the surgery is complete. Most cataract surgery occurs in either an ambulatory surgery center or a hospital. You will be required to report several hours before the scheduled time for your surgery. You will meet with theanesthesiologist who will work with the ophthalmologist to determine the type of sedation that will be necessary. Most cataract surgery is done with only minimal sedation without having to put you tosleep. Numbing drops or an injection around the eye will be used to decrease sensation of the eye.

During the actual procedure, there will be several people in the operating room in addition to your ophthalmologist. These include anesthesiologists and operating-room technicians. While cataract surgery does not normally involve a significant amount of pain, medications are used to minimize the amount of discomfort. The actual removal of the clouded lens will take approximately 20 minutes. You may notice the sensation of pressure from the various instruments used during the procedure. After leaving the operating room, you will be brought to a recovery room where your doctor will prescribe several eyedrops that you will need to take for a few weeks postoperatively. While you may notice some discomfort, most patients do not experience significantpain following surgery; if you do you experience decreasing vision or significant pain, you should contact your ophthalmologist immediately.

What should one expect after the cataract surgery?

Following surgery, you will need to return for visits within the first few days and again within the first few weeks after surgery. During this time period, you will be using several eyedrops which help protect against infection and inflammation. Within several days, most people notice that their vision is improving and that they are able to return to work. During the several office visits that follow, your doctor will monitor for complications. Once vision has stabilized, your doctor will fit you with glasses if needed. The type of intraocular lens you have implanted will determine to some extent the type of glasses required for optimal vision.

What are potential complications of cataract surgery?

While cataract surgery is one of the safest procedures available with a high rate of success, rare complications can arise. Your ophthalmologist will discuss the specific potential complications of the procedures that are unique to your eye prior to having you sign a consent form. The most common difficulties arising after surgery are persistent inflammation, changes in eye pressure, infection, or swelling of the retina at the back of the eye (cystoid macular edema), and retinal detachment. If the delicate bag the lens sits in is injured, then the artificial lens may need to be placed in a different location. In some cases, the intraocular lens moves or does not function properly and may need to be repositioned, exchanged, or removed. All of these complications are rare but can lead to significant visual loss; thus, close follow-up is required after surgery. If you have pre-existing macular degeneration orfloaters, these will not be made better by cataract surgery.

In some cases, within months to years after surgery, the thin lens capsule may become cloudy, causing blurred vision after cataract surgery. You may have the sensation that the cataract is returning because your vision is becoming blurry again. This process is termed posterior capsular opacification, or a "secondary cataract." To restore vision, a laser is used in the office to painlessly create a hole in the cloudy bag. This procedure takes only a few minutes in the office, and vision usually improves rapidly.

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