What are Cataracts?

The lens of the eye is used to focus our sight and is normally clear.  A loss of transparency, sometimes called clouding, of an eye’s lens is referred to as a cataract. The most frequent cause of cataracts is age related changes.  The effect of clouding can range from being mild enough that vision is minimally effected to so severe that all contrast of shapes and motion are lost, allowing the person to only see light and dark.  When the loss of transparency is great enough to significantly obstruct vision, it is called a cataractous lens or more commonly, a cataract.

While aging is the most common cause of cataracts, there are a number of other reasons the lens may cloud over.  These include trauma to the eye, some medications, and diseases such as diabetes.  In some instances babies are born with cataractous lenses.

Cataracts are a clouding of the lens, so it is much like trying to see through a dirty window.  Since it is a transparency problem, rather than a focus problem, glasses or contacts can not sharpen the visual images. Once a cataract has developed, the only option to restore clear vision is to have the cataract surgically removed.  When vision has deteriorated enough that it interferes with a person’s lifestyle, it is time to have cataract surgery.

Cataract surgery is very common, with over a million and a half people having the procedure each year.  It is conducted as an outpatient surgery during which the cataract is removed through a small incision and replaced with a clear artificial lens, specially fitted to persons vision needs.  Just as with any surgical procedure, there are complications and risks which should be discussed with the eye surgeon, but in most cases, vision is improved as is the individual’s quality of life and often independence.
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Cataract Symptoms

There are a variety of types of cataracts and each affects vision in different ways.  For instance, some affect reading vision more significantly than distant vision and vice versa.  In some cases a person who is farsighted, also known as hyperopic, initially experience an improvement in their distant sight.  Conversely, myopic or nearsighted individuals my have a worsening of distant vision.

The typical age related cataract forms slowly and progressively with no pain as vision decreases.  Symptoms may include a decrease in color intensity, glare, especially at night, blurring of vision, or frequent change of eyeglass or contact prescription.  Additionally, there could be a yellowing of images or, rarely, double vision.
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Removal of the cataract with phacoemulsification (phaco)

The cataractous lens is removed by the eye surgeon using ultrasound technology.  The process is known as phacoemulsification or phaco.  After numbing the eye, the surgeon gently breaks up the center of the lens with an ultrasonic oscillation probe.

As the lens breaks up, the fragments are suctioned from the eye.  By breaking up the lens into tiny pieces, its removal can be achieved by using a very small incision which typically does not need sutures.

Most of the lens capsule is left intact and the appropriate intraocular lens is inserted in place of the natural lens.  With successful completion of the procedure, vision returns quickly and normal activities are resumed after a short recovery period.
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Lens replacement with Intraocular Lenses (IOL's)
The removing of a cataractous lens requires the replace of a person’s natural lens with an artificial lens called and Intraocular lens or IOL.  IOL's are one of the most important ophthalmic developments in the past several decades.  Previous to the development of IOL's, patients were forced to wear very thick glasses or contacts after cataract surgery.  Without the corrective lenses, the patients were essentially blind. 

Today’s IOL's give many patients the best vision of their lives.  In addition to replacing the natural lens, IOL's can also correct existing refractive errors which caused the patient to wear glasses before the cataract developed.    Very sophisticated formulas have been developed to determine the corrective prescription lens power for each person.

Currently, IOL's fall into two basic types, foldable and hard.  Foldable lenses are made of acrylic or silicon materials while hard lenses are typically plastic.  The eye surgeon determines which type of lens should be used based on the needs and circumstances of the individual.

Foldable lenses can be rolled up into a small tube and inserted through a small incision which requires shorter recovery time.  Since hard lenses are more rigid, they require as slightly larger incision for insertion.  Once in the eye, the lens performs the duty of the natural lens.  Unlike contact lenses or glasses, they remain in the eye and do not require cleaning or reinsertion.

There have been a number of significant advances in IOL's in the last few years.  One major innovation is the development of the presbyopia correcting lenses which can correct both near and distant vision. For some people, these new lenses can eliminate the need for reading glasses or even bifocal eyeglasses.  While typically used in cataract patients, these lenses are now also being investigated for use in older patients without cataracts for a procedure called Clear Lens Exchange or CLE.
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Posterior Capsulotomy

One of the steps of the cataract surgical procedure is to remove a thin cellophane like capsule located in front (anterior) of the lens.  This gives the surgeon access to the cataractous lens and allows for its removal.  When the lens is implanted, the rear or posterior capsule is left in place. 

While that membrane remains clear, good vision is achieved.  However, in some people, months or even years after their surgery, this membrane becomes cloudy. Symptoms of this include a decrease in vision, difficulty with glare or bright lights, or decreased ability to read.   If this occurs a follow up procedure called posterior capsulotomy may need to be performed.

The posterior capsulotomy is a brief procedure which is performed using a laser to create a small hole in the membrane to allow light to pass through unobstructed.  Most patients resume normal activity immediately with vision improvement in the first day or two.
Complications are rare, but can include an increase in intraocular pressure and retinal detachment.
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