Why Cataract Surgery
CATARACT AWARENESS AND THE NEED FOR CATARACT SURGERY
Blindness due to cataract presents an enormous problem in India not only in terms of human morbidity but also in terms of economic loss and social burden. The WHO/NPCB (National Programme for Control of Blindness) survey has shown that there is a backlog of over 22 million blind eyes (11 million blind people) in India, and 80.1% of these are blind due to cataract. The annual incidence of cataract blindness is about 3.8 million. It remains uncertain as to whether the high levels observed are explained largely by reduced access to cataract surgery or additionally to potential environmental risk factors more prevalent in low-income settings, such as poor diets, occupational sunlight exposure, and use of biomass fuels. Genetic factors may also be relevant, especially if cataract prevalence varies between low-income populations.
What Is a Cataract?
A cataract is a dense, cloudy area that forms in the lens of the eye. A cataract begins when proteins in the eye form clumps that prevent the lens from sending clear images to the retina. The retina works by converting the light that comes through the lens into signals. It sends the signals to the optic nerve, which carries them to the brain.
What Causes Cataracts?
There are several underlying causes of cataracts. These include:
• an overproduction of oxidants in the natural human lens, which are oxygen molecules that have been chemically altered due to normal daily life
• ultraviolet radiation
• the long-term use of steroids and other medications
• certain diseases, such as diabetes
• radiation therapy
• Congenital cataracts also can occur when- during pregnancy, the mother develops infections such as measles or rubella (the most common cause), rubeola, chicken pox, cytomegalovirus, herpes simplex, herpes zoster, poliomyelitis, influenza, Epstein-Barr virus, syphilis and toxoplasmosis.
Symptoms of Cataracts
• blurry vision
• trouble seeing at night
• seeing colors as faded
• increased sensitivity to glare
• halos surrounding lights
• double vision in the affected eye
• a need for frequent changes in prescription glasses
Ophthalmologists/Optometrists will perform a comprehensive eye examination to check for cataracts and to assess your vision. This will include an eye chart test to check your vision at different distances, slit lamp examination to diagnose the stage of cataract after the dilation of eyes, tonometry to measure your eye pressure.
CLASSIFICATION OF CATARACTS:
1. Nuclear Cataract:
Nuclear Cataracts are the most common. These are frequently related to aging. The appearance ranges from a faint haze in the pupil to a deep burnished yellow, similar to a smoky fog. As a result, the individual reports a “yellowing” of vision. Frequently, there is a shift in glasses prescription to become less hyperopic (“far sighted”) or more myopic (“near sighted”).
2. Posterior Subcapsular Cataract:
Posterior Subcapsular cataracts appear in the center of the lens of the eye. Most frequently, they occur on the posterior (back) part of the lens. There is not any usual shift in lens prescription such as is found in nuclear cataracts. Because they appear more in the center of the lens, if the pupil is small, such as in bright light, the vision is reduced. In contrast, in reduced light, such as at night, the pupil is open, allowing light to go around the cataract. As such, vision at night may be better. Or, the individual may feel driving at night is easier than sunny days. This type of cataract can also be related to a systemic disease or prolonged steroid use.
3. Cortical Cataract:
The appearance of cortical cataracts show up as “spokes of a wheel”. The opacity tends to be most pronounced in the periphery of the pupil. This means that in bright daylight and normal room lighting, the vision is not as affected as when the pupil is more dilated at night.
4. Morganian (Mature) Cataract:
The Mature Cataract is diffusely opaque or white. When the nucleus of the lens has turned yellow, and has fallen by gravity to the lower part of the lens, it is said to be a “Morganian Cataract”. Cataract surgery is highly recommended when this type of cataract develops due to the fact that damage will ultimately occur to the inside of the eye. Secondary Glaucoma is a frequent complication.
5. Congenital Cataracts:
In congenital cataracts the lens opacity is present at birth. These type cataracts can be caused from genetic or maternal reasons. There are many different morphological shapes. In infants, congenital cataracts are usually bilateral and recognized by the appearance of a white pupil, which is detected during a routine eye examination in the baby’s first six months of life. Maternal reasons for the development of cataracts may include: syphilis, rubella or secondary to amniocentesis. There are various types of congenital cataracts. The specific treatment depends on the type and severity.
6. Infantile or Juvenile Cataracts:
Infantile or Juvenile Onset cataracts have a definite genetic origin and tend to co-exist with other abnormalities such as inborn errors of metabolism, identified chromosomal abnormalities, and other eye conditions. Causes for these type of cataracts include: diabetes, galactosemia, hyperlysinemia, homocystinuria, Down Syndrome, Turners Syndrome, Muscular Dystrophy, Idiopathic Hypoparathyroidism, Rieger’s anomaly, aniridia and retinitis pigmentosa.
7. Traumatic Cataract:
Traumatic cataracts can result from two major types of injuries:
Perforating Eye Injuries: If a sharp object penetrates the eye (ex. wire) and penetrates the capsule of the lens in the eye, a cataract will frequently develop. These usually will develop at a fast rate.
Blunt Eye Injuries: If the eye is injured by a blunt compression type injury, a cataract may develop up to several years after the injury. Additionally, with this type of injury, the zonules attaching to the lens capsule may be torn or injured, which may impair the “near point” focusing ability for the individual.
8. Secondary Cataract:
A Secondary cataract, or Capsular Fibrosis, is directly related to a specific disease, systemic disorder or chemical agent such as prescription medications. For example, long term use of prednisone (steroid) frequently will result in cataracts. Many other medications have been found to cause cataracts.
Treatment of Cataracts
Cataracts are treated using surgeries: Removal of the cataractous human lens and replacement with an artificial Intra-Ocular lens(IOL).If the cataract is in an immature stage, your Ophthalmologist may be able to help you manage your symptoms using eyeglasses, magnifying lenses, or sunglasses with an anti-glare coating.
Surgery is recommended when cataracts prevent you from going about your daily activities, such as reading or driving, unable detecting faces or objects. It’s also performed when cataracts interfere with the treatment of other eye problems.
Two types of Cataract surgeries are widely done nowadays: Phaco-Emulsifaction and Extra-Capsular Cataract Extraction.
One surgical method, known as phacoemulsification, involves the use of ultrasound waves to break the lens apart and remove the pieces.
Extracapsular Capsular Cataract Extraction involves removing the cloudy part of the lens through a long incision in the cornea. After surgery, an artificial intraocular lens is placed where the natural lens was.
Prevention of Cataracts
To reduce your risk of developing cataracts:
• protect your eyes from UVB rays by wearing sunglasses outside
• have regular eye exams
• stop smoking
• eat fruits and vegetables that contain antioxidants
• maintain a healthy weight
• keep diabetes and other medical conditions in check