Cataract.....

Cataract
What Is a Cataract?
A cataract is a clouding of the lens of the eye. The lens is a clear oval structure with three layers: the nucleus, the cortex, and the capsule. It may help to think of the lens structure as a peach, where the nucleus is the peach pit, the cortex is the flesh of the peach surrounding the pit, and the capsule is the peach skin, or elastic covering of the lens. You have a cataract when the nucleus becomes opaque (that is, it is no longer clear) or when small opacities develop in the cortex that block or scatter light.
What Are the Different Types of Cataract?
There are three types of cataracts that affect different parts of the lens, have different symptoms and cause different vision problems.
• Nuclear cataract is the most common type of cataract, and is related to the aging process. The nucleus gradually hardens and becomes opaque, causing difficulty identifying colors and seeing at a distance.
• Cortical cataract is the next most common type, often affecting people who have diabetes. Wedge-shaped opacities develop in the cortex, interfering with the passage of light. This can result in problems with glare and loss of contrast, as well as difficulty with distance and near vision.
• Subcapsular cataract develops under the back of the capsule or elastic covering of the lens and is common in people with diabetes or high myopia, adults with retinitis pigmentosa, and in people taking cortisone. This type of cataract can cause glare sensitivity and blur.
Symptoms
In the early stages, only a doctor can detect a cataract because there may not be any symptoms. When you do start to notice changes in vision, they may include:
• blurry distance vision, especially outdoors;
• streaks or rays of light seeming to come from headlights and stop lights;
• instinctively shading your eyes from the sun or feeling more comfortable wearing a visor;
• print appearing faded and lacking in contrast;
• colors appearing faded or changed in hue. Blue may appear to be green and yellow may look white.
Because these may also be symptoms of other eye conditions, it is important to see your eye doctor annually, or whenever you notice a persistent change in vision.
Diagnosis
To detect a cataract, an eye care professional examines the lens. A comprehensive eye examination usually includes:
Visual acuity test
This eye test, which measures how well you see at various distances, has two components. It measures accurate vision without correction, as well as best corrected vision confirmed by refraction.
Pupil dilation
The pupil is widened with eyedrops to allow your eye care professional to see more of the lens and retina and look for other eye problems.
Tonometry
This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma. One type of the test uses a purple light to measure pressure. Another type, known as the "air puff" test, measures the resistance of the eye to a puff of air. Your eye care professional may also do other tests to learn more about the structure and health of your eye.
Risk Factors
Although we do not yet know what causes cataracts, studies have identified the following risk factors:
• Aging
• Long-term exposure to sunlight
• Cigarette smoking
• High cholesterol/triglycerides
• Diabetes
• Certain eye conditions - cataract is often associated with myopia, retinitis pigmentosa, and retinopathy of prematurity
• Cortisone medication taken orally for a long time
• Eye injury
What You Can Do to Reduce Risk
Currently, there is no proven way to prevent the development of cataracts other than controlling medical conditions that may be the cause. Antioxidants like beta carotene and vitamins C and E have been identified as reducing the risk of developing cataracts and slowing their progression. Wearing UV-protected sunglasses to reduce exposure to ultraviolet light can also reduce risk.
Treatment
Cataracts are treated with surgery. Surgery can often be postponed until the cataract begins to seriously affect your ability to function. Often in the early stages of a cataract you can get the help you need from a new distance prescription eyeglass, stronger reading glasses, better lighting or specialized optical devices such as magnifiers or telescopes. Continue to see your eye doctor regularly to evaluate how the cataract is progressing. When glasses or magnifiers no longer help, or when you develop cataracts in both eyes, surgery is the only option. There is no medicine or other treatment that can dissolve or remove cataracts.
Cataract surgery is an outpatient procedure performed by an ophthalmologist. The process involves removing the lens and replacing it with a plastic lens implant. There are two types of surgery: extracapsular extraction and phacoemulsification.
The extracapsular method has been the standard for over a decade, but with advancing technology in surgical equipment and intraocular lens implants for both methods, phacoemulsification has gradually become the procedure of choice in the majority of cases. Phacoemulsification does not usually require stitches, has a shorter recovery period, and is suitable for most individuals. Your doctor will decide which is best for your eye based on the condition of your lens, the history of previous eye surgery, and the ability of the pupil to dilate. The visual outcome is the same for both methods. In general, both types of surgery require local anesthesia and the dilation of the pupil to ensure that the lens is exposed as widely as possible. Since you will be awake during surgery, you can tell the doctor if you are experiencing any discomfort. Usually you will be able to go home in a few hours, but you must bring a family member or friend to accompany you home.
After surgery, you will need some time to recover, generally a few days to a few weeks. Your eyes will be examined the next day, and the doctor will give you eye drops to prevent infection and reduce inflammation. You may need to wear an eye shield at night and/or sunglasses when out of doors. If you take medication for other conditions, be sure to discuss this with your doctor, both before and after surgery. Also discuss resuming physical activity and any plans involving air travel. Both before and after surgery it is important to discuss any concerns or worries you have. Do not hesitate to ask questions
Cataract and the Aging Eye

What is a cataract?
A cataract is a clouding of the lens of the eye. To understand what a cataract is, it's helpful to know that the lens is a clear, oval structure with three layers: nucleus, cortex and capsule. The analogy of a peach can be used to describe these layers. The nucleus or center of the lens is the pit of the peach, the cortex is the flesh surrounding the pit, and the capsule or elastic covering is the skin of the peach. The lens is supported inside the eye by tiny ligaments (zonules) that support the lens capsule.
In a young person, the lens is crystal clear and allows light to pass through and focus on the retina. As the lens ages, the nucleus turns yellow and loses its ability to accommodate (focus for close work) although the lens usually remains clear. As the lens continues aging, the nucleus turns from yellow to amber and ultimately to brown. Aging changes do not necessarily result in a cataract unless the nucleus becomes opaque, or opacities that block or scatter light develop in the cortex or under the capsule.
Are all cataracts the same?
There are three types of cataracts: nuclear, cortical and subcapsular. Each type affects a specific part of the lens, causing different symptoms and vision problems.
A nuclear cataract is the most common type of cataract and is age-related. In a nuclear cataract, the center of the lens gradually hardens and becomes opaque. As the nucleus changes color, from white to yellow to amber, it may also become so opaque that your eye doctor cannot clearly see the details of the retina. At that point, you might experience difficulty identifying colors and seeing at a distance. Some people become near-sighted (myopic) as a result of a nuclear cataract and notice an improved ability to read without glasses. Individuals with a nuclear cataract do not usually complain of increased light sensitivity. Surgical removal of a nuclear cataract may be safely postponed when symptoms do not interfere with daily activities. However, your eye doctor needs to monitor the condition of the lens, and will recommend surgery based on your symptoms and on the appearance of the cataract.
The second most common cataract is the cortical cataract. It starts as wedge-shaped opacities or "spokes" in the cortex (the layer between the nucleus and the capsule) that extend from the periphery towards the center of the lens. As the spokes reach the center, they interfere with the passage of light, causing glare and loss of contrast. Many people with diabetes develop this type of cataract. Although a cortical cataract usually develops slowly, it may impair both distance and near vision so significantly that surgery may be suggested at a relatively early stage.
A subcapsular cataract develops slowly and starts as a small opacity under the elastic covering (capsule), usually at the back of the lens (posterior). Significant visual symptoms may not appear until late in its development as the opacity increases, blocking light and causing glare sensitivity and blur. Typically, this type of cataract is found in people with diabetes or high myopia, adults with retinitis pigmentosa, and in people taking cortisone. If glare can be controlled with tinted lenses and anti-glare filters, the need for surgery is not as urgent.
Common signs and symptoms
• Distance vision is blurry, especially outdoors, but, in some cases, reading vision may be improved.
• The edges of stairs and curbs are difficult to discern.
• Streaks or rays of light seem to come from light sources, such as headlights and stop lights, at night.
• You instinctively shade your eyes from the sun or feel more comfortable wearing a visor.
• The reflection of light from metal on a car, road pavement, or a bright, cloudy sky may cause glare.
• Fluorescent ceiling lights or bright reading lamps may cause glare.
• Print appears faded and lacking in contrast.
• Sunglasses appear to reduce your vision.
• Highway signs, particularly on bright days, are difficult to read.
• Print is difficult to read in dim light.
• Colors appear faded or changed in hue. For example, blue may appear as a shade of green, white as gray or beige, and yellow as white.
Risk factors
While there are no known causes, studies have identified a number of risk factors:
• Age
Cataracts are a normal part of aging. Approximately 50% of Americans between 65 and 74, and 70% over age 75 have cataracts.
• Excessive exposure to sunlight
Boaters, sunbathers, and people who do not habitually wear adequate protective eyewear are at risk.
• Cigarette smoking
• High cholesterol / triglycerides
• Diabetes Mellitus
Probably related to faulty glucose metabolism.
• Cortisone medication

Taken orally over a long period of time for medical conditions such as severe arthritis, lupus or related diseases.
• Eye injury
Can cataracts be prevented?
Currently, there is no proven way to prevent the development of cataracts other than controlling medical conditions that may be the cause. Antioxidants like beta carotene and vitamins C and E have been identified as reducing the risk of developing cataracts and slowing their progression.
How is a cataract diagnosed?
An ophthalmologist, optometrist or family practitioner can diagnose the presence of a cataract through a routine eye examination. However, once a cataract is detected, your ophthalmologist or optometrist will monitor its progression. The eye examination evaluates:
• the general health of your eye and the type of cataract;
• how your activities are affected by the cataract;
• whether your cataract should be surgically removed by your ophthalmologist.
Dilation of pupils
Dilating your pupils is a procedure that allows your eye doctor (optometrist or ophthalmologist) to see the inner parts of your eye more clearly in order to evaluate the general health of your retina and optic nerve. Your doctor may use a special prism (gonioscope) to determine the safety of this procedure. Once established, eyedrops are used to dilate your pupils. An ophthalmoscope, which has a light source that can focus on the inside of the eye, enables the eye doctor to view your retina and optic nerve. A slit lamp – a microscope with a light source that can focus on the lens of the eye – may be used to determine the position and extent of the cataract. If your vision improves after the pupil has been dilated, your eye doctor may prescribe eyedrops for daily use.
Nonsurgical treatment options
If surgery is not advisable or should be delayed as long as possible – as in the case of people with only one eye due to an accident or eye disease – optical devices can alleviate some of the visual symptoms. Very strong reading glasses and hand-held magnifiers that enlarge print can be useful to continue routine activities such as reading a newspaper or a recipe in a cookbook. As a rule, an illuminated hand or stand magnifier with a built-in light source may be helpful unless the light causes glare, which is most common with cortical cataracts. Other optical devices, such as a hand-held monocular telescopic lens, can aid in seeing street signs as well as directories in buildings and airports. Sunglasses can decrease glare and increase contrast so that objects are more easily seen.
For information on the different types of surgical options.


What surgical procedures are used to remove the cataract?
Performed by an ophthalmologist in a hospital or surgical center, cataract surgery is an elective outpatient procedure. During surgery, the lens is removed and replaced with an artificial one (implant) that performs the same function.
Two types of surgical procedures are commonly performed: extracapsular extraction and phacoemulsification. The extracapsular method has been the standard for over a decade, but with advancing technology in surgical equipment and intraocular lens implants for both methods, phacoemulsification has gradually become the procedure of choice in the majority of cases. The ophthalmologist usually makes the decision at the time of the diagnostic evaluation based on the dilation of the pupil, the state of the lens, the effect of other eye problems such as glaucoma on the mechanics of the eye, and the history of previous eye surgery.
Not all cataracts can be removed by phacoemulsification. If a pupil is too small and doesn't dilate, the lens is too hard, the cataract is too advanced, the eyeball is too deep set or the brow too prominent, then the extracapsular method, which requires stitches, is preferred. Eventually, after about six weeks and once stitches are removed, postoperative vision is comparable with either method.
The procedure and steps of cataract surgery
1. Incision at the border of the cornea and sclera of about ½ inch
2. Opening of the lens capsule to expose nucleus
3. Lens nucleus removed from capsular bag in one piece
4. Cortical material removed by aspiration (suction)
5. Plastic lens implant placed in the capsular bag
6. Eye sutured with seven to nine nylon stitches
7. Postoperative astigmatism due to stitches
8. Removal of some of the stitches after six or more weeks to reduce astigmatism
9. Corrective glasses after stitches are removed, or when astigmatism subsides (usually six to seven weeks after surgery)
Phacoemulsification
1. Small tunnel incision of 3/16 inch under a conjunctival flap in the sclera or directly in the cornea into the anterior chamber
2. Opening of the lens capsule to expose nucleus
3. Lens nucleus fragmented and removed from capsular bag by ultrasonic emulsification and suction
4. Cortical material removed by aspiration (suction)
5. Plastic lens implant placed in the capsular bag
6. No stitch or, in some cases, one stitch to close the small incision

7. Little or no astigmatism
8. No stitches to remove. If there's one stitch, it remains there without any ill effect
One stich to close small incision

9. Corrective glasses after the eye stabilizes, usually a few weeks after surgery
What kind of anesthesia can be expected
In the majority of cases, the doctor performs cataract surgery under local anesthesia and light sedation. However, general anesthesia is appropriate in special situations: a very tense or apprehensive person, a person who cannot cooperate, or a person with an elongated large eyeball (high myopia) for whom local anesthesia injections are contraindicated.
Local anesthesia and preparation of the eye is the same regardless of which surgical procedure is used. Your pupil is dilated an hour before surgery with several types of dilating drops applied to the eye at approximately 10-15 minute intervals. Dilation allows a wider exposure to the front surface of the lens. If your pupil does not dilate well, the iris opening may be enlarged at the time of surgery or your ophthalmologist may elect to do extracapsular surgery, which does not require maximum dilation.
The ophthalmologist or anesthesiologist gives an injection around or under the eyeball to anesthetize the eye and put the eye muscles to rest. This makes it impossible for you to move your eye during the operation. An intravenous needle is inserted into an arm vein to infuse saline or sugar solution. This allows the anesthesiologist to give you additional sedation or medication if needed. Since you are not asleep, you will be able to tell the ophthalmologist if you experience any discomfort. The anesthesiologist monitors your breathing rate and blood pressure throughout the surgery.
Most people can go home after a few hours, although it is required that they be accompanied by a family member or friend. In special circumstances, a person may be admitted to the hospital overnight. However, the latter is more the exception than the rule.
What is stitchless surgery?
Stitchless surgery is a relatively recent development. The wide incision of the extracapsular method, which requires seven to nine stitches, causes postoperative astigmatism for several weeks. To reduce this recovery period and to attain an almost instant visual recovery, a different technique was developed.

Eye sutured with seven to nine nylon stitches
By entering the eye either in the sclera or at the border of the cornea, a narrow opening is dissected through the sclera and cornea into the eye. This allows an ultrasonic probe to be easily inserted into the eye to emulsify the cataract. The implant is then inserted through the tunnel into the capsular bag behind the iris. Saline is injected to raise the eye pressure until the eye seals itself shut. Although the slanted incision is watertight and does not require a stitch, some ophthalmologists place one stitch at the opening of the incision as a precaution.

What is a surgical microscope?
One of the significant advances in instrument development is the surgical microscope that provides a uniform light level and magnifies the details of the eye. Surgery could not be done without it. The ophthalmologist looks through a binocular eyepiece with an internal light source that is focused by a foot pedal. The surgeon's other foot controls the suction or phacoemulsification machine leaving both hands free to hold the surgical instruments.
Are lens implants safe?
The plastic lens implant (intraocular lens) that replaces the cloudy lens is the most important part of cataract surgery. The plastic is nonreactive and cannot cause an allergic reaction. Rejection of an implant is rare and caused only by some extraneous factor unrelated to the lens material itself. Lens implants are permanent and safe unless there is a complication that prevents the safe introduction of a lens at the time of surgery. In those situations, an implant can be introduced as a secondary procedure at a later date.

Plastic lens implant inserted through the incision at the border of the cornea
What is a secondary lens implant?
Over two decades ago, when the entire lens, including the capsule, was removed (intracapsular extraction), one had to wear corrective contact lenses or thick "cataract" glasses. Now, many of these people can be evaluated for a special lens implant (secondary lens implant) by their ophthalmologist. Not everyone is a good candidate and only your ophthalmologist can tell you if a secondary implant is right for you. This outpatient surgical procedure is simple, done under minimal local anesthesia, and usually takes about 10 minutes.



Can a cataract come back?
A cataract can't come back, but a "secondary membrane" or thickening of the elastic lens capsule can form within weeks or months of surgery. This causes your vision to become slightly cloudy. It occurs in about 40% of cases and is easily and permanently removed through a procedure called a YAG capsulotomy, which uses a special cutting laser. The procedure takes approximately five minutes and is done with anesthetic drops on an outpatient basis by an ophthalmologist. In this procedure, a small opening is made in the capsule behind the lens implant so that light can again reach the retina. The procedure is painless but you need to have your eye pressure checked the next day. In addition, you must use eye drops for a few days. Your eyeglass prescription will not change.
What can go wrong?
Although cataract surgery is technically successful in over 95% of those treated, visual outcome will vary from person to person, particularly for those with multiple eye conditions. As with any surgery, there are risks. That's why doctors do surgery only on one eye at a time.