Cataract
Introduction to Cataract
As people grow older the natural eye lens become opaque leading to blurred vision. It is called cataract. It is one of the leading causes of visual disability and preventable blindness.
1As the world’s population ages, cataract-induced visual dysfunction and blindness is on the rise. Genetic as well as environmental factors contribute to its development.
2,3 It can occur in one or both eyes. It gradually develops over a long period of time and the loss of vision is gradual and painless, hence people do not realize till late that they have a cataract. Therefore, it is important to have regular eye check-ups especially after the age of 60 years. The burden of cataract blindness is a major challenge for all developing countries.
4 The blindness control efforts have been successful in arresting the increasing prevalence of blindness in India and there is hope that the goals of the ‘Vision 2020--right to sight’ initiative can be achieved if there is strong political will and prioritized action.
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During 1981–1982 India performed around 0.5 million cataract surgeries, and this increased to 4.8 million in 2006 with 90% intraocular lens acceptance.
Epidemiology (Occurence of Cataract in Different Groups)
In India a nationwide survey was undertaken in 1999–2001 to document the magnitude and causes of blindness. The highest risk was among those aged 70 years and above and the illiterates. Cataract was responsible for 62.4% of bilateral blindness. Prevalence of cataract blindness was 5.3% (95% CI: 4.97–5.62). Reduction in blindness prevalence among people aged 50 years and above was observed compared to earlier studies.
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The biggest problem todeveloping countries in terms of human morbidity, economic loss,and social burden is due to pediatric cataract blindness.6A review of pediatric cataract cases operated between January 2003 and March 2005 in some parts of central India it showed congenital cataracts were in 88 (17.5%) eyes. Traumatic cataracts were noted in 170 (33.9%) eyes. The proportion of cataract was higher in males than in females.2
Development of Cataract
The lens is a clear part of the eye, which is made mostly of water and protein. It consists of three layers: the outer layer (capsule), the middle layer (cortex) and the inner layer (nucleus). It lies behind the iris and the pupil and focuses the light on the retina. In the older people the protein molecule on the lens clumps together and the lens become cloudy. It is usually start as a small, opaque spot and slowly grow larger. This cloudiness blocks the light reaching the retina, causing vision problems, which is called cataract. Vision is not usually affected until a large area of the lens becomes cloudy. Besides age related, there are less common types of cataract where lens become cloddy even in children and young people.
Risk Factors for Cataract
The biggest risk factor for cataracts is aging. Other risk factors are diabetes, family history of cataracts, smoking, UV exposure and eye trauma. Additionally, some cataracts are congenital, meaning they are present since birth.
Types of Cataract
Read more about the Types of Cataract...
Symptoms of Cataract
Cataracts are generally painless gradually developing condition. The most common symptoms are:
- Blurred or hazy vision
- Light sensitivity
- Halos around lights
- Impaired night vision
- Yellowing or fading of color vision
- Double vision
- Frequent change in spectacle prescriptions
Diagnosis and Tests of Cataract
- Torch light examination can diagnose cataract. Iris shadow on the lens is seen as a milky white opacity.
- Ophthalmoscopy: The lens media appears hazy.
- General examination: To find out the conditions like diabetes or hypertension.
- Detailed dilated eye examination including direct and indirect ophthalmoscopy can be done to confirm the condition.
- A-scan ultrasonography: To determine the axial length of the eye and intraocular lens (IOL) power.
- Complete blood investigation including bleeding time and clotting time.
Treatment of Cataract
Cataract is a progressive disease and treatment is essentially removal of lens followed by IOL or spectacles. Till date nowhere in the world an anti-cataract drug is approved for cataract. However, agents with unproven efficacy are
Read more about the Treatment of Cataract...
Cataract Surgeries
Phacoemulsification or Phaco
A small incision is made on the side of the cornea, (limbus) in the manner of Z and a tiny probe is inserted into the eye. This emits ultrasound waves that soften and break the lens so that it can be removed by suction. Then, foldable lens is placed in that position and the flap is replaced without any suture. It is also called ‘small incision cataract surgery’. Today most of the cataract surgeries are done by this method.
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Extracapsular Surgery
Here a long incision is made on the side of the cornea, and the lens is removed as one piece. The remaining parts are removed by suction. Once cloudy lens is removed, often it is replaced by an artificial lens called an intraocular lens (IOL). An IOL is a clear, plastic lens that requires no care and becomes a permanent part of the eye. Some may not have an IOL because of the other eye disease or some problems during surgery. For these patients, a soft contact lens or glasses that provide high magnification may be suggested.
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Preoperative Medications for Cataract
- Prophylactic antibiotic capsules/tablets.
- Prophylactic antibiotic eye drops.
- Tab. Anxit 0.25 mg, a night before surgery.
- Topical mydriatic eye drops for the dilatation of the pupil.
After the Surgery of Cataract
Most of the patients notice an instant improvement in sight, although complete healing may take several months. Antibiotic and steroid combination eye drops are to be used for up to two months after surgery. Most of them go home on the same day of the surgery, and will probably be able to carry on with normal daily activities, but do think about the following:
- Avoid rubbing the eye; better to wear an eye shield if the person is a restless sleeper.
- Do not lift any heavy things, and avoid strenuous exercise and swimming.
- If it is windy, take care of your eyes.
- Take care of washing the hair; avoid getting soapy water in the eye.
- Avoid wearing eye make-up until complete recovery.
Possible Problems of Cataract
Operative procedure for cataract is one of the most successful operations. An unforeseen serious complication occurs in less than 2% of patients. Thickening of the lens casing the part of the eye that holds the lens in place is among the most common and easily correctable complications. This is treated by laser treatment.3
Prevention of Cataract
Cataract is a natural age-related process and cannot be prevented. There are certain measures, which can reduce the risk of its development or can slow down its progression:
- By reducing exposure to UVB radiation wearing sunglasses and a hat with a brim and avoiding direct UV exposure.
- By smoking cessation.
A good nutritious diet including green leafy vegetables, fruits and other foods with antioxidants can help reduce the risk of age-related cataract.
The National Eye Institute suggests that if one with the age of ³60 years you should have an eye exam at least every 2 years.8 Widespread surgical services capable of delivering good vision rehabilitation accessible to all in need can help reducing disability and blindness.3Appropriate treatment at appropriate time can save the eye sight.
Written by: Healthplus24 team
Date last updated: December 28, 2008