Cataract

Cataract surgery is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision. Many patients' first symptoms are strong glare from lights and small light sources at night, along with reduced acuity at low light levels. During cataract surgery, a patient's cloudy natural lens is removed and replaced with a synthetic lens to restore the lens's transparency.
Following surgical removal of the natural lens, an artificial intraocular lens implant is inserted (eye surgeons say that the lens is "implanted").

Why do cataracts occur?

Precisely why cataracts occur is unknown; however, most cataracts appear to be caused by changes in the protein structures within the lens that occur over many years and cause the lens to become cloudy. Rarely, cataracts can present at birth or in early childhood as a result of hereditary enzyme defects. Severe trauma to the eye, eye surgery, or intraocular inflammation can also cause cataracts to develop more rapidly. Other factors that may lead to development of cataracts at an earlier age include excessive ultraviolet light exposure, diabetes, smoking, or the use of certain medications, such as oral, topical, or inhaled steroids. Other medications that are more weakly associated with cataracts include the long-term use of statins and phenothiazines.

What are the symptoms of cataracts?

Cataract development is often equated to looking through a dirty windshield of a car or smearing grease over the lens of a camera. Cataracts may cause a variety of complaints and visual changes, including blurred vision, difficulty with glare (often with bright sun or automobile headlights while driving at night), dull color vision, increased nearsightedness accompanied by frequent changes in eyeglass prescription, and occasionally double vision in one eye. A change in glasses may help initially once vision begins to change from a cataract; however, as the cataract continues to grow, vision becomes cloudy, and stronger glasses or contact lenses will no longer improve sight.
Cataracts typically develop gradually and are usually not painful or associated with any eye redness or other symptoms unless they become extremely advanced. Rapid and/or painful changes in vision raise suspicion for other eye diseases and should be evaluated by an eye-care professional.

Who is a candidate for cataract surgery?

Surgery is recommended for most individuals who have vision loss and are symptomatic from a cataract. If you have significant eye disease unrelated to cataracts that limits your vision, your ophthalmologist may not recommend surgery.

What are the treatment modalities for cataract?

Currently, the two main types of cataract surgery extraction performed by the ophthalmologists are phacoemulsification (phaco) and conventional extracapsular cataract extraction (ECCE). In both types of surgery an Intraocular lens is usually inserted. Foldable lenses are generally used when phaco is performed while non-foldable lenses are placed following ECCE. The small incision size used in phacoemulsification (2-3mm) often allows "sutureless" wound closure. ECCE utilises a larger wound (10-12mm) and therefore usually requires stitching, although sutureless ECCE is also in use.
Cataract extraction using intracapsular cataract extraction (ICCE) has been superseded by phaco & ECCE, and is rarely performed.

Phacoemulsification is the most commonly performed cataract procedure in the developed world. However, the high cost of a phacoemulsification machine and of the associated disposable equipment means that ECCE remains the most commonly performed procedure in developing countries.

What are the different types of intraocular lenses implanted after cataract surgery?

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 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 to correct astigmatism as well as 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 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 contacts for clearest vision.

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 eye drops 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, and once vision has stabilized, 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 procedure 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, 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 extremely rare but can lead to significant visual loss; thus, close follow-up is required after surgery.

In some cases, within months to years after surgery, the thin lens capsule may become cloudy, and you may have the sensation that the cataract is returning because your vision is becoming blurry again. This process is termed posterior capsule 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.