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A cataract is a cloudy (opaque) area in the normally clear crystalline lens of the eye. Vision deteriorates when cloudiness obstructs light traveling through the lens to the inner lining of the back of the eye (retina), where focusing occurs with retinal stimulation. Cataracts manifest first as small, scattered cloudy areas. They are painless and occur over a period of a few months to several years.
Aging and accompanying biochemical changes within the lens cause cataracts. Recent research indicates that ultraviolet radiation from sunlight may be a major factor in development of the condition. When cataracts significantly impair vision, surgical removal and replacement of the entire lens is the only remedy. An early stage of cataract development can produce increased hardness and density at the center of the lens (nuclear sclerosis). In an advanced stage, a cataract may appear brownish rather than the typical clear lens. Cataracts in adults can occur in the outer covering around the lens (capsule), the center (nucleus), or the area around the center (cortex). Cataracts may stop developing in the early stages and cause only minor or no vision decrease. If growth continues, vision will worsen, and treatment will be needed.
Cataracts that result from aging (senile) are the most common. Other causes include injury (trauma); hypertension; connective tissue diseases; ocular infection; exposure to x-rays; drugs such as corticosteroids, diuretics or thiazines; and diseases such as diabetes mellitus. Drugs used for treatment of a disease that damages the optic nerve (glaucoma) also have been implicated. Smoking and alcohol use have been found to increase cataract occurrence. High levels of uric acid and low levels of riboflavin, vitamin E, iron, and protein are also thought to contribute to cataract formation. Cataracts are the leading cause of blindness in the world and the third leading cause of preventable blindness in the US.
Risk: Individuals who spend considerable time in the sunlight and/or who smoke or drink alcohol may be at higher risk of developing cataracts as they age. Women have a slightly higher incidence. Cataracts also are more likely to develop in blacks than whites. Incidence and Prevalence: More than half of people aged 65 or older have cataracts ("Cataract"). Cataract removal is the most common surgery for this age group. |
Source: Medical Disability Advisor
| History: Blurred or cloudy vision and the inability to see properly at night due to low contrast or glare are among symptoms of cataracts. Individuals also may have difficulty perceiving light sources, which can produce glare or halos. Indistinct or monocular double vision (diplopia) may occur continually or sporadically. An individual may report a new though temporary ability to read without glasses. Vision may lack subtle variations in shading. Pain typically is absent unless the cataract swells and causes increased pressure in the eyes (acute secondary glaucoma). Vision loss can be sudden or gradual. Physical exam: A physical exam using an ophthalmoscope and slit lamp will reveal a cataract in a dilated pupil. Visual acuity is measured at a distance using high and low lighting with the Snellen chart. Impairment of ability to see letters or shapes at a distance may be detected. Tests: An examination (refraction) using various lenses is performed to see if glasses or contact lenses can improve vision. Eyedrops to dilate the pupil enable a thorough examination. A type and grade then are assigned to the cataract. Cataracts are commonly classified according to the color, location, and severity of the cloudiness. A central (nuclear) cataract is graded according to the percentage of area affected. In cases of cataracts found in peripheral (cortical) or outer covering (posterior subcapsular), grades range from 1 (least affected) to 4 (most affected). The pressure inside the eye (intraocular pressure) can be measured to rule out glaucoma (tonometry). Tests that measure the individual's ability to see different shades of color, as well as to measure contrast sensitivity and glare, may be performed.
In certain cases, tests are done to predict the increase in vision that is expected to occur after cataract removal (potential acuity meter or laser interferometer testing). When an artificial lens insertion is planned, the length of the eye is measured and the curvature of the cornea is evaluated. |
Source: Medical Disability Advisor
| When glasses or contact lenses no longer improve impaired vision, surgery is considered. Cataract removal under an operating microscope usually involves techniques of phacoemulsification or extracapsular cataract extraction, allowing the outer covering (capsule) of the lens to remain in place. The most common procedure involves inserting a small probe and using ultrasound vibration to break apart the lens, which is suctioned out of the eye (phacoemulsification). The cataract and natural lens also may be removed manually through the extracapsular cataract extraction technique. An artificial lens may then be inserted (intraocular lens implantation). The lens more commonly is inserted behind the colored portion of the eye (iris), but also may be placed in front of the iris. Eyedrops and oral medication may be used before, during, and after surgery to reduce eye pressure. Antibiotics may be used to prevent infection. Anti-inflammatory agents also might be administered to prevent further damage caused by the eye tissue's reaction to injury. The eye may then be covered with a shield. If an artificial lens is not inserted, thick glasses (aphakic) or contact lenses will be needed and are prescribed when the eye is fully recovered. Glasses or contact lenses may be needed even if an artificial lens was inserted. Newly developed implantable lenses now offer options for correcting certain types of pre-existing vision deficiencies, such as hyperopia, myopia, presbyopia, or astigmatism. |
Source: Medical Disability Advisor
| Cataracts usually continue to develop over time, causing vision to worsen. Most individuals experience improved vision following surgical removal with artificial lens insertion, along with improved quality of life and mental status. In some cases, additional treatment (YAG laser capsulotomy) will be required if a secondary cataract forms. In rare cases, retinal detachment or other serious complications of surgery may cause blindness. |
Source: Medical Disability Advisor
| Because cataracts may be present in only one eye or may develop at different rates in both eyes, attempts to improve vision with glasses or contact lenses may result in objects being seen as larger or smaller than actual size. The eyes may resist working together to gauge distance. Different lens prescriptions may need to be used for each eye and finely tuned until the best possible vision is obtained. Problems during surgery or the pre-existence of other eye diseases may rule out insertion of an intraocular lens. Following surgery, a secondary cataract commonly forms when the back portion of the lens capsule clouds over (posterior capsular opacification or secondary cataract). A laser procedure then might be required to incise this membrane, allowing for improved vision (YAG laser capsulotomy). |
Source: Medical Disability Advisor
| Lighting may need adjustment, or a hat or visor may be required to reduce glare. Performance of tasks requiring reading, driving, or operation of machinery may be problematic, depending on the extent of postoperative visual acuity. The individual may need to wear glasses, filtered glasses, or contact lenses. Eyestrain may result in the need to close the eyes during rest breaks. Sunshine and strong light may need to be avoided. Physical activity, lifting, and bending may be restricted for a short period of time following surgery. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Has individual been properly tested to confirm cataract diagnosis and rule out the possibility of an eye injury or other diseases?
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Have appropriate methods and tests been applied to determine the extent of the cataract condition?
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Has individual experienced complications, related to either the cataract or its treatment, that may impact recovery?
Regarding treatment:
- Was artificial lens properly positioned?
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Is healing taking place as expected or has the process been complicated by an infection or injury?
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Has individual achieved optimal visual results following cataract removal?
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Have prescriptive lenses been finely tuned until the best possible vision is obtained?
Regarding prognosis:
- If vision was not significantly improved with the cataract removal, can vision be further corrected with prescription glasses or contact lenses?
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Has posterior capsular opacification occurred?
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Did individual undergo a laser procedure to clear up an after cataract or secondary cataract? Was the procedure effective?
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Did the surgically inserted artificial lens provide adequate vision correction? Does it need to be replaced with a different type of lens?
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Are further corrective procedures warranted?
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Source: Medical Disability Advisor
| "Cataract Surgery Overview." injuryboard.com. 21 Dec. 2004. 21 Dec. 2004 <http://www.injuryboard.com/view.cfm/Topic=800>. |
Source: Medical Disability Advisor