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A cataract is a clouding of the eye's natural lens, which lies behind the iris
[pic]The colored part of your eye surrounding the pupil. This pigmented membrane lies between the cornea and the lens; it acts as a diaphragm to widen or narrow the opening called the pupil, thereby controlling the amount of light that enters the eye.
and the pupil.
[pic]The round, dark center of the eye, which opens and closes to regulate the amount of light the retina receives.
Cataracts are the most common cause of vision loss in people over age 40 and are the principal cause of blindness in the world. In fact, there are more cases of cataracts worldwide than there are of glaucoma, macular degeneration and diabetic retinopathy combined, according to Prevent Blindness America (PBA).
Today, cataracts affect more than 50 million Nigerians age 40 and older. And as the Nigerian Population ages, more than 60 million Nigerians are expected to have cataracts by the year 2020.
Types of cataracts include:
• A subcapsular cataract occurs at the back of the lens. People with diabetes, high farsightedness. Hyperopia, or farsightedness, is a common vision problem, affecting about a fourth of the population. People with hyperopia can see distant objects very well, but have difficulty focusing on objects that are up close. Farsighted people sometimes have headaches or eye strain and may squint or feel fatigued when performing work at close range. If you get these symptoms while wearing your eyeglasses or contact lenses, you may need an eye exam and a new prescription. This vision problem occurs when light rays entering the eye focus behind the retina, rather than directly on it. The eyeball of a farsighted person is shorter than normal.
Many children are born with hyperopia, and some of them "outgrow" it as the eyeball lengthens with normal growth.
Sometimes people confuse hyperopia with presbyopia, which also causes near vision problems but for different reasons. Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.You can't escape presbyopia, even if you've never had a vision problem before. Even people who are nearsighted will notice that their near vision blurs when they wear their usual eyeglasses or contact lenses to correct distance vision. Presbyopia is widespread in the United States. According to U.S. Census Bureau data, over 135 million Americans were age 40 and older in 2008, and the country is growing older: The median age reached 36.8 in 2008, up 1.5 years since 2000. This growing number of older citizens generates a huge demand for eyewear, contact lenses and surgery that can help presbyopes deal with their failing near vision.When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm's length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may develop headaches, eye strain or feel fatigued. Presbyopia is caused by an age-related process.
This differs from astigmatism, (Astigmatism might be the most misunderstood vision problem. Even the name is challenging to many people, who incorrectly call it "stigmatism". Like nearsightedness and farsightedness, astigmatism is a refractive error, meaning it is not an eye health problem; it simply is a problem with how the eye focuses light. In an eye with astigmatism, light fails to come to a single focus on the retina to produce clear vision. Instead, multiple focus points occur, either in front of or behind the retina (or both).
Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks. Squinting also is a very common symptom of uncorrected astigmatism. Astigmatism usually is caused by an irregularly shaped cornea. Instead of the cornea having a symmetrically round shape (like a baseball), it is shaped more like a football, with one meridian being significantly more curved than the meridian perpendicular to it. (To understand what meridians are, think of the front of the eye like the face of a clock. A line connecting the 12 and 6 is one meridian; a line connecting the 3 and 9 is another.) The steepest and flattest meridians of an eye with astigmatism are called the principal meridians.
In some cases, astigmatism is caused by the shape of the lens inside the eye. This type of astigmatism is called lenticular astigmatism, to differentiate it from the more common corneal astigmatism. There are several types of astigmatism:
• Myopic astigmatism. One or both principal meridians of the eye are nearsighted. (If both meridians are nearsighted, they are myopic in differing degree.)
• Hyperopic astigmatism. One or both principal meridians are farsighted. (If both are farsighted, they are hyperopic in differing degree.)
• Mixed astigmatism. One prinicipal meridian is nearsighted, and the other is farsighted.
Astigmatism also is classified as regular or irregular. In regular astigmatism, the principal meridians are 90 degrees apart (perpendicular to each other). In irregular astigmatism, the principal meridians are not perpendicular. Most astigmatism is regular corneal astigmatism, which gives the eye a football shape. Irregular astigmatism can result from an eye injury that has caused scarring on the cornea, from certain types of eye surgery or from keratoconus, a disease that causes a gradual thinning of the cornea. Astigmatism often occurs early in life, so it is important to schedule an eye exam for your child to avoid vision problems in school from uncorrected astigmatism.
nearsightedness and farsightedness, which are related to the shape of the eyeball and are caused by genetic and environmental factors. Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic over time. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. Other, less popular theories exist as well.
Presbyopia Treatment: Eyewear Eyeglasses with bifocal or progressive addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main part of the spectacle lens contains a prescription for distance vision, while the lower portion of the lens holds the stronger near prescription for close work.
The eye's lens stiffens with age, so it is less able to focus when you view something up close. (Image: Varilux) Progressive addition lenses are similar to bifocal lenses, but they offer a more gradual visual transition between the two prescriptions, with no visible line between them. Reading glasses are another choice. Unlike bifocals and PALs, which most people wear all day, reading glasses typically are worn just during close work. If you wear contact lenses, your eye doctor can prescribe reading glasses that you wear while your contacts are in. You may purchase readers over-the-counter at a retail store, or you can get higher-quality versions prescribed by your eye doctor. Presbyopes also can opt for multifocal contact lenses, available in gas permeable or soft lens materials. Another type of contact lens correction for presbyopia is monovision, in which one eye wears a distance prescription, and the other wears a prescription for near vision. The brain learns to favor one eye or the other for different tasks. But while some people are delighted with this solution, others complain of reduced visual acuity and some loss of depth perception with monovision. Because the human lens continues to change as you grow older, your presbyopic prescription will need to be increased over time as well. You can expect your eye care practitioner to prescribe a stronger correction for near work as you need it.
Presbyopia Treatment: Surgery. Surgical options to treat presbyopia also are available. One example is Refractec Inc.'s conductive keratoplasty or NearVision CK treatment, which uses radio waves to create more curvature in the cornea for a higher "plus" prescription to improve near vision. The procedure is performed on one eye only for a monovision correction.
Farsightedness can be corrected with glasses or contact lenses to change the way light rays bend into the eyes. If your glasses or contact lens prescription begins with plus numbers, like +2.50, you are farsighted. You may need to wear your glasses or contacts all the time or only when reading, working on a computer or doing other close-up work.
retinitis pigmentosa. Retinitis pigmentosa (RP) is a rare, inherited disease in which the light-sensitive retina of the eye slowly and progressively degenerates. Eventually, blindness results. When retinitis pigmentosa is suspected, visual field testing likely will be conducted during or after your routine eye exams to determine the extent of peripheral vision loss. Other specialized eye tests may be needed to determine whether you have lost night or color vision. The first signs of retinitis pigmentosa usually occur in early childhood, when both eyes typically are affected. Night vision can be poor, and the field of vision may begin to narrow.When RP first starts to appear, the light-sensing cells that are responsible for vision in dim light (rods) gradually deteriorate and seeing at night becomes more difficult. During later stages of retinitis pigmentosa, only a small area of central vision remains, along with slight peripheral vision. It's very difficult to predict the extent of vision loss or how fast it will progress when you have retinitis pigmentosa. Your eye doctor will monitor the health of your retinal cells and administer tests to determine how well you can see. At some point, you may be advised to drive only during the daytime or on well-lighted streets at night. Eventually you may be unable to see well enough to drive at all. Rather than being considered a single disease, retinitis pigmentosa instead is viewed as a group of diseases affecting how light-sensitive cells in the back of the eye function. Not much is known about what causes retinitis pigmentosa, except that the disease is inherited.
Retinitis pigmentosa causes deterioration of light-sensitive cells in the back of the eye.The eye condition is associated with at least 32 different genes,* which control traits that are passed along in a number of different ways. At times, the genetic trait is dominant and likely to be passed along to a child when a parent has RP. At other times, the trait for retinitis pigmentosa is recessive and may be present for many generations before it appears in a family member. This means that, even if your mother and father don't have retinitis pigmentosa, you can still have the eye disease when at least one parent carries an altered gene associated with the trait. In fact, about 1 percent of the population can be considered carriers of genetic tendencies for retinitis pigmentosa.* Retinitis pigmentosa occurs in about 1 of every 4,000 people in the United States. When the trait is dominant, it is more likely to show up when people are in their 40s. When the trait is recessive, it tends to first appear when people are in their 20s.** Currently there is no cure for retinitis pigmentosa.
those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.
• A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging.
• A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
Cataract Symptoms and Signs
A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting.
Hazy or blurred vision may mean you have a cataract.
A cataract may make light from the sun or a lamp seems too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did.
The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called "second sight."
Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. On the other hand, a subcapsular cataract may not produce any symptoms until it's well-developed.
If you think you have a cataract, see an eye doctor for an exam to find out for sure.
What Causes Cataracts?
The lens inside the eye works much like a camera lens, focusing light onto the retina. It adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens is mostly made of water and protein. The protein is arranged in a precise way that keeps the lens clear and let light pass through it.
But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see.
No one knows for sure why the eye's lens changes as we age, forming cataracts. Researchers are gradually identifying factors that may cause cataracts — and information that may help to prevent them.
Many studies suggest that exposure to ultraviolet light is associated with cataract development, so eye care practitioners recommend wearing sunglasses and a wide-brimmed hat to reduce your exposure.
Other types of radiation may also be causes. For example, a 2005 study conducted in Iceland suggests that airline pilots have a higher risk of developing nuclear cataract than non-pilots and that the cause may be exposure to cosmic radiation. A similar theory suggests that astronauts, too, are at risk from cosmic radiation.
Other studies suggest people with diabetes are at risk for developing a cataract.
The same goes for users of steroids, diuretics and major tranquilizers, but more studies are needed to distinguish the effect of the disease from the consequences of the drugs themselves.
Some eye care practitioners believe that a diet high in antioxidants, such as beta-carotene (vitamin A), selenium and vitamins C and E, may forestall cataract development. Meanwhile, eating a lot of salt may increase your risk.
Other risk factors include cigarette smoke, air pollution and heavy alcohol consumption.
An eight-year study of more than 30,000 postmenopausal Swedish women found a 14 percent increased risk for cataract removal among those who used HRT at any time and an 18 percent increased risk for current HRT users.
HRT use combined with regular alcohol consumption appeared to create a 42 percent increased risk of cataract removal, compared with women who had never used HRT or alcohol.
The HRT study was reported in the March 2010 issue of Ophthalmology.
Does Eating Less Meat Reduce Your Risk for Cataracts?
Could eating more greens and less meat help you delay the onset of cataracts?
This interesting question has received a lot of public comment since researchers at the University of Oxford published a study** in March 2011 that compared cataract incidence with dietary intake.
The study examined the dietary surveys filled out by 27,670 self-reported nondiabetic people aged 40 or over and monitored their medical records to see if and when cataracts developed. Strong correlations showed up between cataract risk and diet type.
The risk was greatest for high meat eaters (who ate more than 3.5 ounces of meat each day), and it decreased from one group to the next, in this order: moderate meat eaters, low meat eaters, fish eaters (people who eat fish but no other meat), vegetarians and vegans. In fact, the risk for vegans was roughly 40 percent lower than for the high meat eaters.
Does this mean you should stop eating meat? Maybe, maybe not. The study doesn't answer every question. Perhaps the reason for the lower risk is that if you eat less meat, you probably eat more vegetables. And perhaps those veggies are providing nutrients that reduce cataract risk.
Also, vegetarians and vegans may tend to lead healthy lifestyles, avoiding cataract risk boosters such as smoking, excess sun exposure and diabetes. It may be true that cataracts are inevitable if you live long enough, but living healthy just might delay them for a good long time..
When symptoms begin to appear, you may be able to improve your vision for a while using new glasses, strong bifocals, magnification, appropriate lighting or other visual aids.
Think about surgery when your cataracts have progressed enough to seriously impair your vision and affect your daily life. Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure to regain vision.
Cataract surgery is very successful in restoring vision. In fact, it is the most frequently performed surgery in the United States, with more than 3 million Americans undergoing cataract surgery each year, according to PBA. Nine out of 10 people who have cataract surgery regain very good vision, somewhere between 20/20 and 20/40.
During surgery, the surgeon will remove your clouded lens and in most cases replace it with a clear, plastic intraocular lens (IOL).
In cataract surgery, the cloudy natural lens must be removed from the eye. After that, in most cases a permanent intraocular lens (IOL) implant replaces the natural lens to restore focusing power.
When to have cataract surgery often is a subjective decision, based on how well you are able to see during routine activities. You might be able to drive, watch television and work at a computer for quite a few years, even after you are first diagnosed with cataracts.
However, if you have cataracts, you may eventually start to notice "ghost" images and declining visual clarity, which can't be corrected with glasses or contacts. Colors may begin to look faded, too. If your functional vision is impaired significantly and it becomes difficult for you to perform your normal daily activities, it may be time for cataract surgery.
Preparing for Cataract Surgery
Once you and your eye doctor have decided that you will have your cataract removed, the eye surgeon will examine you. For the immediate time period before and after cataract surgery, ask your surgeon if you should continue your usual medications and nutritional supplements.
As an example, a common drug that treats men with enlarged prostates — Flomax and similar medications known as alpha-blockers — could cause problems associated with intraoperative floppy iris syndrome (IFIS) during cataract surgery. Patients on Flomax or similar medications should notify their eye surgeon before undergoing cataract surgery.
You may be given a choice of implantation with a regular single-vision (monofocal) intraocular lens or a presbyopia-correcting intraocular lens for replacement of your eye's natural lens.
Determining the right IOL for you can be based on many factors, including your lifestyle and ability to pay. If you are interested in correcting presbyopia, which all people have beginning at around age 40, you potentially could restore your ability to see at all distances with a multifocal IOL or accommodating IOL.
However, you must consider that extra cataract surgery costs do occur with "premium" IOLs, even though they may reduce or eliminate dependency on eyeglasses.
Before cataract surgery, your eye will be thoroughly measured in a preliminary eye exam to determine the proper power of the intraocular lens that will be placed in your eye. If you choose a premium IOL, you may need extra tests to make sure measurements are exact and that you don't have other vision problems that might hamper the performance of the IOL.
If you need cataracts removed from both eyes, surgery usually will be done on only one eye at a time. An uncomplicated surgical procedure lasts only about 10 minutes. However, you may be in the outpatient facility for 90 minutes or longer, because extra time will be needed for preparation and recovery.
At least a few days to weeks typically will be needed between surgeries, so that your first eye has the chance to heal and be evaluated in a follow-up exam for any possible problems.
What Happens During Cataract Surgery?
Cataract surgery usually is done on an outpatient basis. You may be asked to skip breakfast and avoid drinking liquids, depending on the time of your surgery. Also, do not wear eye makeup on the day of surgery. Upon arrival at the facility, you will be given eye drops to dilate your pupils and perhaps a sedative to help you relax. A local or topical anesthetic will make the operation painless. [pic]The skin around your eye will be thoroughly cleansed, and sterile coverings will be placed around your eye and head.Under an operating microscope, at least one small incision is made into the eye. The surgeon will then remove your cloudy lens (the cataract).This procedure can be performed using an ultrasound-driven instrument that "sonically" breaks up the cataract (phacoemulsification) as it is suctioned (aspirated) out of the eye.
In another surgical method, special instruments are used to mechanically break up the cloudy lens into small pieces (phacofracture) and remove them directly from the eye through a small incision.The surgeon will insert a plastic or silicone IOL inside the eye to replace the natural lens that was removed. Most incisions used for cataract surgery are self-sealing. However, on occasion, incisions may need to be sutured. When stitches are used, they rarely need to be removed.
Cataract Surgery Recovery
When the operation is over, the surgeon will usually place a protective shield over your eye. After a short stay in the outpatient recovery area, you will be ready to go home. Plan to have someone else drive you home.You will need to administer eye drops, as prescribed by your surgeon, several times daily during the next few weeks. You also will need to wear your protective eye shield while sleeping or napping, for about a week after surgery. You will be given sun shades to help protect your eye in bright light.While your eye heals, you might experience some blurred vision during the first few days or even weeks following the procedure.
During at least the first week of your recovery, it is essential that you avoid:
• Strenuous activity and heavy lifting (nothing over 25 pounds).
• Bending, exercising and similar activities that might stress your eye while it is healing.
• Water that might splash into your eye and cause infection. Keep your eye closed while showering or bathing. Also, avoid swimming or hot tubs for at least two weeks.
• Any activity (such as changing cat litter boxes) that would expose your healing eye to dust, grime or other infection-causing contaminants.
Although the basic postoperative instructions are similar among most eye surgeons, each surgeon may have specific recovery instructions depending on the outcome of your surgery. Always follow your surgeon's specific instructions, which you will receive prior to your discharge from the outpatient facility.
Complications of Cataract Surgery
Glaucoma or a buildup of pressure within the eye (intraocular pressure) also occurs sometimes after cataract surgery. If your eye pressure remains high, you may need additional treatment such as eye drops, a laser procedure, pills or additional surgery. Far more rarely, you might experience problems such as a decentered intraocular lens that might need to be repositioned or replaced in a second surgery.Various complications, ranging from minor to serious, also can take place as a direct result of the surgical procedure, including tearing of the posterior capsule holding the intraocular lens in place.
Phacoemulsification in cataract surgery involves insertion of a tiny, hollowed tip that uses high frequency (ultrasonic) vibrations to "break up" the eye's cloudy lens (cataract). The same tip is used to suction out the lens.
After the eye's natural lens is removed during cataract surgery, an artificial or intraocular lens is implanted to take its place. Detached retinas also are possible in a small percentage of people who have undergone cataract surgery, particularly if they have unusually long eyes associated with higher degrees of nearsightedness.* Some eye surgeons dispute this direct association with cataract surgery, because highly nearsighted people already are at risk of getting a detached retina with or without cataract surgery. Cumulative rates of detached retinas occurring in highly myopic general populations who underwent cataract surgery or refractive lens exchange are roughly 1 percent in some studies, which is about the same risk if you never underwent a procedure. However, a common complication that creates a "secondary cataract" may require a YAG laser capsulotomy procedure. A high myope who undergoes both cataract surgery and a subsequent YAG laser capsulotomy may have a significantly greater risk of developing a detached retina.**
Endophthalmitis causing widespread inflammation or infection of the eye can be a serious side effect of cataract surgery that can lead to permanent vision loss and even blindness. Various studies indicate that endophthalmitis occurs in about one out of every thousand cataract surgeries. Endophthalmitis also is more likely to be seen in people with compromised immune systems associated with conditions such as diabetes.
However, even serious cataract surgery complications often can be resolved with appropriate follow-up treatments.
Cataract Surgery Outcomes
A comprehensive study reported in Archives of Ophthalmology in 1994 noted that 95.5 percent of healthy eyes achieved 20/40 uncorrected vision (legally acceptable for driving) or better outcomes following cataract surgery. Of the more than 17,000 eyes evaluated, fewer than 2 percent had sight-threatening complications.
Bruising or a black eye can result from cataract surgery, if an injection is used to numb the eye.
Remember that sight-threatening complications often are associated with individuals who are much older or who already have poor underlying health affecting how their eyes heal. Also, some people have complications because their cataracts are far more advanced or "hardened" at the time of surgery, making them difficult to remove.
A Swedish study published in the British Journal of Ophthalmology in November 1999 found that self-reported outcomes among people who had undergone cataract surgery were less satisfactory when other eye problems were present. Younger people undergoing cataract surgery reported the highest satisfaction levels.
The British journal also reported study results in December 2000 indicating that people in their 60s undergoing cataract surgery were 4.6 percent more likely to achieve 20/40 uncorrected vision or better than people in their 80s.
Device that creates bursts of laser energy at an extremely fast rate measured in terms of a unit known as a femtosecond (one quadrillionth of a second). These ultra fast energy pulses precisely target and break apart tissue or other substances at a molecular level, without damaging adjacent areas.
Laser Vision Correction
Laser eye surgery has become an extremely popular and effective method for correcting nearsightedness (myopia), farsightedness (hyperopia), and astigmatism (irregular curvature of the lens), and is the most common procedure available for those who wish to eliminate the need for glasses or contact lenses. Laser eye surgery itself is a type of refractive surgery which is less painful and requires less recovery time than many other types of eye surgery.
Though each type of laser eye surgery is unique, they all involve correcting vision problems by reshaping or contouring part of the eye through the use of lasers. This process changes the eye from its current shape to an improved shape, resulting in the same effect that comes from wearing corrective lenses, all without the use of blades or needles– only painless and accurate lasers.
However, everyone’s eyes are unique, so it is important to research the different options available to you to help correct and improve your vision, at all distances and in all light conditions.
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