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CATARACTS: A Leading Cause of Preventable Blindness. Neda Karimi, M.D. University of Kansas Department of Ophthalmology August 4, 2004. Epidemiology. Cataracts are the leading cause of blindness in the world More than 1.3 million cataract procedures are performed in the U.S. each year

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cataracts a leading cause of preventable blindness

CATARACTS: A Leading Cause of Preventable Blindness

Neda Karimi, M.D.

University of Kansas Department of Ophthalmology

August 4, 2004

  • Cataracts are the leading cause of blindness in the world
  • More than 1.3 million cataract procedures are performed in the U.S. each year
  • Visual disability associated with cataracts account for 8 million physician office visits each year
  • The earliest reference to cataracts can be found in Hindu writings from the 5th century BC
  • The word Cataract comes from the Greek word meaning “Waterfall”
  • Until the mid 1700’s, it was thought that cataract was formed by opaque material flowing, like a waterfall into the eye
  • The human lens is a naturally clear structure located behind the iris and supported by the zonules
  • The lens is avascular-It does not have a vascular supply
  • The basic lens consists of a central nucleus surrounded by the cortex contained within the lens capsule
  • When light passes through the pupil, it is focused by the lens to produce clear, sharp images on the retina, the light-sensitive membrane on the back of the eye that functions like the film of a camera
  • When this arrangement is disturbed in any way, the transparency is lost
  • This results in scattering of light, blurring, and blocking of the image
  • The lens is made mostly of water and protein fibers
  • The protein fibers are arranged in a precise manner that makes the lens clear and allows light to pass through without interference
  • With aging, the composition of the lens undergoes changes and the structure of the protein fibers breaks down
  • Some of the fibers begin to clump together, clouding areas of the lens, and leading to the loss of transparency
Clouding of the lens is a normal part of aging
  • About half of Americans older than 65 have some degree of clouding of the lens
  • According to one study, after age 75, 39% of men, and 46% percent of women in the U.S. have visually significant cataracts
Cataracts produce a gradual, painless, progressive loss of vision, and many patients are unaware of vision problems
  • Generally do not cause pain, or abnormal tearing
  • But as the clouding progresses, the cataract eventually interferes with your vision
Commonly affect distance vision
  • Cause problems with glare
  • In the early stages, stronger lighting and eyeglasses can help deal with the vision problems
  • If impaired vision jeopardizes your normal lifestyle, you might need surgery
Patients often describe trying to look through a fogged-up window
  • Clouded vision can make it more difficult to drive a car, read, or see details
  • Blurred vision
  • Increasing difficulty with vision at night
  • Glare, especially at night
  • Halos around lights
  • The need for brighter light for reading
  • Double vision in a single eye
  • Fading or yellowing of colors
These may also be symptoms of other eye conditions, therefore it is important to see your ophthalmologist annually, or if there is a persistent change in vision
Pain, redness, discharge, or irritation in the eye are usually not signs or symptoms of a cataract, but may be signs and symptoms of other eye disorders
hypermature cataract
Hypermature Cataract
  • A cataract isn't dangerous to the eye unless the cataract becomes completely white, a condition known as an overripe (hypermature) cataract
  • This can cause inflammation, eye pain and headache
  • A hypermature cataract is extremely rare and needs removal
types of cataract
Types of Cataract
  • The lens consists of three layers
  • The outer layer is a thin, clear membrane
  • It surrounds a soft, clear material (cortex)
  • The hard center of the lens is the nucleus
  • A cataract can form in any part of the lens
nuclear cataract
Nuclear Cataract
  • Occurs in the center of the lens
  • In its early stages, the patient may become more nearsighted or even experience a temporary improvement in reading vision
  • This so-called “second sight” disappears as the lens gradually turns yellow and begins to cloud the vision
  • Seeing in dim light and driving at night may be especially troublesome
cortical cataract
Cortical Cataract
  • Begins as whitish, wedge-shaped streaks on the outer edge of the lens cortex
  • As it slowly progresses, the streaks extend to the center and interfere with light passing through the nucleus
  • Both distance and near vision can be impaired
  • Patients also have problems with glare and loss of contrast
subcapsular cataract
Subcapsular Cataract
  • Starts as a small, opaque area just under the capsule shell, usually at the back of the lens, right in the path of light on its way to the retina
  • This type of cataract may occur in both eyes but tends to be more advanced in one eye than the other
  • Often interferes with reading vision, reduces your vision in bright light and causes glare or halos around lights at night
  • Why age-related changes happen to the lens is not known
  • One possibility is damage caused by unstable molecules known as free radicals
  • Smoking and exposure to UV light are two sources of free radicals
  • General wear and tear on the lens over the years also may cause the changes in protein fibers
  • Age-related changes in the lens are not the only cause of cataracts
  • Some infants are born with cataracts or develop them during childhood
  • Such cataracts may be the result of the mother having contracted rubella during pregnancy
  • Metabolic disorders
congenital cataracts
Congenital Cataracts
  • Responsible for nearly 10% of all visual loss in children worldwide
  • Approximately 0.03% of newborns have some form of congenital cataract
  • Most are not associated with additional developmental problems
  • Around one fifth of these patients have a family history of congenital cataract but in up to half of all cases there is no family history
In the case of a newborn infant, a cataract causes the immature visual system to be deprived of the stimulation needed for normal development
  • If left untreated, permanent visual loss may occur
  • Unilateral cataracts are more likely to cause visual loss because of the competition between the two eyes
If the cataract is small there may be only slight blurring of vision with near normal visual development
  • If the cataract is larger, or located more posteriorly, it can effect visual development
  • In some cases this can lead to permanent amblyopia (lazy eye)
  • Without adequate stimulation central vision can be permanently effected
Outcome is very much dependent on the type of cataract
  • Some congenital cataracts impair visual development only to a small degree and may never require surgery
  • If the cataract is only in one eye, there is a strong tendency for the child to prefer the healthy eye
    • The eye affected by the cataract rarely achieves normal vision, therefore removal of the cataract is indicated
etiology of pediatric cataracts
Etiology of Pediatric Cataracts
  • Hereditary
    • Autosomal dominant form most common
  • Genetic and Metabolic Diseases
    • Down syndrome
    • Marfan’s syndrome
    • Myotonic Dystrophy
  • Maternal Infections
    • Rubella, Syphilis, Toxoplasmosis, Varicella
Ocular Anomalies
    • Aniridia-Absence of iris at birth
  • Toxic
    • Corticosteroids, Radiation
  • Trauma
risk factors in adults
Risk Factors In Adults
  • Exposure to sunlight (UV light)
  • Smoking
  • Diabetes
  • Trauma (blunt or penetrating)
  • Family history of cataracts
  • Corticosteroid therapy
  • Radiation exposure
  • Electrical injury
  • Myotonic dystrophy
  • Uveitis- Ocular inflammation
risk factors
Risk Factors
  • Everyone is at risk of developing cataracts simply because age is the single greatest risk factor
  • By age 65 about half of all Americans have developed some degree of lens clouding
Cataracts develop sooner in diabetic patients than in non-diabetic patients
  • This is caused by shifts in the glucose, electrolyte, and water balance within the lens
  • Fluctuating vision and rapid shift to near sightedness are symptoms of diabetes
clinical findings
Clinical Findings
  • The most common objective finding associated with cataracts is decreased visual acuity
  • This is measured with an office wall chart or near-vision card
visual acuity
Visual Acuity
  • Acuity refers to the sharpness of vision or how clearly you see an object
  • In this test, your eye doctor checks to see how well you read letters from across the room
  • Eyes are tested one at a time, while the other eye is covered.
  • Using the chart with progressively smaller letters from top to bottom, to determine the level of vision
  • This is performed by your doctor to see if the decrease in vision is simply due for need for new glasses, or if there is another process at work that accounts for the decrease in visual acuity
slit lamp exam sle
Slit Lamp Exam (SLE)
  • SLE allows the ophthalmologist to see the structures of the eye under magnification
  • The microscope is called a slit lamp because it uses an intense slit of light to illuminate your cornea, iris, and lens
  • These structures are viewed in small sections to detect any small abnormalities
dilated exam
Dilated Exam
  • Dilating drops are placed in the eyes to dilate the pupils wide and provide a better view to the back of the eyes
  • It allows the ophthalmologist to examine the lens for signs of a cataract and, if needed, determine how dense the clouding is
dilated exam40
Dilated Exam
  • It also allows for examination of the retina and the optic nerve.
  • Dilating drops usually keep your pupils open for a few hours before their effect gradually wears off
When pupils are dilated, patients will have difficulty focusing on close objects
  • With your pupils open this wide, sunglasses are helpful on a sunny day, and you may need a driver to drive you home
other causes of painless vision loss
Other Causes of painless Vision Loss
  • Cataract
  • Retinal detachment
  • Macular degeneration
  • Diabetes mellitus
  • Glaucoma
  • Retinal artery occlusion
Retinal detachment is often accompanied by floaters, flashes of light, and loss of peripheral vision, which is often described as a gray curtain or shade covering all or part of the visual field
  • Risk factors include a history of previous ocular trauma, nearsightedness, retinal detachment in the fellow eye, or a family history of retinal detachment
Macular degeneration usually causes a slow, progressive loss of central vision
  • Symptoms of acute vision loss and distortion result from leakage from abnormal subretinal vessels
  • Patients should be referred to a retina specialist immediately
Diabetic retinopathy may also contribute to vision loss
  • Findings include dot-and-blot hemorrhages, microaneurysms, dilated and tortuous vessels, and neovascularization of the disk and retina
  • Cataracts often obscure the fundus, making assessment of diabetic retinopathy difficult
Open-angle glaucoma produces slow, painless visual field loss that usually begins peripherally
  • Optic nerve damage and subsequent loss of peripheral vision occur at normal as well as elevated intraocular pressures
  • With progressive optic nerve damage and visual field loss, central vision is the last to be affected
Cataracts are the most treatable cause of decreased vision in the United States
  • For most patients, observation and frequent eyeglass prescription changes are sufficient
  • When activities of daily living, such as driving, reading, working, and self-care are affected surgery should be discussed
Cataract Surgery should be considered when changes in eyeglasses no longer help, quality of life is jeopardized, and cataract removal is likely to have an impact on vision
  • Make sure that eyeglasses or contact lenses are the most accurate prescription possible
  • Improve the lighting in your home with more or brighter lamps
  • When outside during the day, wear sunglasses to reduce glare
  • Limit night driving
Think about how the cataract affects your daily life
    • Can you see to do your job and drive safely
    • Do you have problems reading or watching television?
    • Is it difficult to cook, shop, climb stairs or take medications?
    • How active are you? Does lack of vision affect your level of independence?
    • Are you afraid you'll trip or fall or bump into something?
Sometimes a cataract should be removed even if it doesn't cause major problems with vision
    • If it is preventing the treatment of another eye problem, such as age-related macular degeneration, diabetic retinopathy or retinal detachment
If you have cataracts in both eyes and decide to have surgery, your eye doctor typically removes the cataract in one eye at a time
  • This allows time for the first eye to heal before the second eye surgery
Cataract surgery is the most common operation performed on patients over 65 years of age
  • More than 95% of patients have improved vision after surgery
  • Benefits include improvement in uncorrected and best-corrected visual acuity, improved binocularity, depth perception, and increased peripheral vision to enhance patients' ability to drive, read, work, and manage their own medications
Advances in surgical technique and more sophisticated technology have helped make surgery a safe and effective treatment for cataracts
  • Prior to surgery, your eye doctor measures the size and shape of your eye to determine the proper lens implant power
  • This measurement is made with a painless ultrasound test
Cataract surgery is typically an outpatient procedure that takes less than an hour
  • Most people are awake and need only local anesthesia
  • On rare occasions some people may need general anesthesia if they have difficulty laying flat or have claustrophobia
Two things happen during cataract surgery — the clouded lens is removed, and a clear artificial lens is implanted
  • During phacoemulsification, phaco for short, the surgeon makes a small incision, where the cornea meets the conjunctiva
The surgeon then uses the probe, which vibrates with ultrasound waves, to break up (emulsify) the cataract and suction out the fragments
Once the cataract is removed, a clear artificial lens is implanted to replace the original clouded lens
  • This lens implant is made of plastic, acrylic or silicone and becomes a permanent part of the eye
Some IOLs are rigid plastic and implanted through an incision that requires several stitches (sutures) to close
  • However, many IOLs are flexible, allowing a smaller incision that requires no stitches
Patients usually go home the same day
  • Patients are seen in the office the next day, the following week, and then again after a month so that he or she can check the healing progress
  • It's normal to feel mild discomfort for a couple of days after surgery
  • You may wear an eye patch or protective shield the day of surgery
  • Your doctor may prescribe medications to prevent infection and control eye pressure
post op course
Post-op Course
  • Patients are usually examined 1 day, 1 week and then one month after the surgery date
complications of surgery
Complications of Surgery
  • Vitreous Loss- 3.1%
  • Vitreous Hemorrhage-0.3%
  • Uveitis-1.8%
  • Increased Eye Pressure- 1.2%
  • Retinal Detachment- 0.7%
  • Endophthalmitis- 0.13%
post operative period
Post Operative Period
  • Contact your doctor immediately if you experience any of the following signs or symptoms after cataract surgery:
    • Vision loss
    • Pain that persists despite the use of over-the-counter pain medications
    • A definite increase in eye redness
    • Light flashes or multiple spots (floaters) in front of the eye
    • Nausea, vomiting or excessive coughing
posterior subcapsular opacity
Posterior Subcapsular Opacity
  • This condition occurs when the back of the lens capsule eventually becomes cloudy and blurs vision
  • PCO can develop months or years after cataract surgery
  • Occurs approx. 20% percent of the time
Treatment for PCO is simple and quick
  • Laser capsulotomy is a quick, painless outpatient procedure that usually takes less than five minutes
  • Capsulotomy means "cutting into the capsule" and YAG is an abbreviation of yttrium-aluminum-garnet, the type of laser used for the procedure
yag laser capsulotomy
YAG Laser Capsulotomy
  • A technique in which a laser beam is used to make a small opening in the clouded capsule to let light pass through
post yag
Post YAG
  • Afterward, patients typically stay in the doctor's office for about an hour to make sure the eye pressure is not elevated
  • In some people, particularly those who have glaucoma or are extremely nearsighted, YAG laser surgery can raise eye pressure
  • Other complications are rare but can include swelling of the macula and a detached retina
Most cataracts occur with age and can't be avoided altogether
  • Regular eye exams remain the key to early detection
  • You can take steps to help slow or prevent the development of cataracts
Do not smoke
    • Smoking produces free radicals, increasing your risk of cataracts.
  • Eat a balanced diet
    • Include plenty of fruits and vegetables.
  • Ultraviolet light protection since UV light may contribute to the development of cataracts
  • Diabetes Control
new frontiers
New Frontiers
  • Researchers are continuing to explore new ways to prevent and treat cataracts, such as developing medications that would reduce or eliminate the need for surgery
  • Until then, cataract surgery is the method to restore vision