Causes of Cataract
The human lens is clear and transparent. It loses its transparency due to various reasons and becomes cloudy, which is known as cataract. The causes and risk factors of cataract are discussed in detail below.
Am I at risk for cataract? Risk factors of cataract
The following risk factors can participate in progression of the disease which is commonly noticed:
cataract is more common in old age or when people with known co morbid cross the age of 40 years. With advancing age, the tensile strength with which the iris holds the lens, becomes weak, the proteins present in the lens tend to disintegrate and cause cataract. People with age of above 6o years usually have a cataract which becomes mature and whitish in color.
Systemic diseases such as diabetes can increase the risk of developing cataract. Normally, the lens takes glucose required for it from the aqueous humor around it but when there is excessive glucose in the body and there is more uptake of the glucose by the lens, the lens swells up and it can lead to clouding of the lens.
Excessive exposure to Sunlight
People who get exposed to sunlight for a long time are more prone to develop cataract as the ultraviolet rays coming from the sunlight can damage the lens and cause blurred vision and other cataract symptoms.
Trauma to the eye
Foreign bodies that enter the eye or any eye injury that damages the lens or the structures around the lens can later cause blurring of vision and increase the risk of getting cataract.
Any Previous eye related surgery
Patients who undergo eye surgeries may develop cataract later in life as the capsule of the lens can get damaged easily during eye surgery.
Smoking is one of the main factors that can precipitate the formation of cataract. It can increase the oxidative stress in the lens and damage it. One of the components that is present in smoke is cadmium which gets deposited in the lens of the eye and makes the crystalline and transparent part opaque and cloudy.
Excessive use of alcohol
Excessive alcohol intake can cause eye related diseases such as Age-related Macular Degeneration and can lead to cataract formation as well by inducing oxidative stress in the lens and make it disintegrate.
Prolonged use of certain medications such as corticosteroids
Steroids can cause increased pressure in the eye by changing the levels of aqueous humor that nourishes the lens and can cause glaucoma, and also increasing the risk of developing cataract.
The increased pressure in the blood vessels of the whole body including the eye can result in diseases of the eye and can lead to damage to the blood vessels in the eye, which results in decreased supply of nutrients to the eye and increases the chance of getting cataract.
Radiologists and technicians working radiological fields are at higher risk of getting cataract, as the micro-rays damage the proteins present in the lens and disintegrate the lens to cause cataract.
Causes of congenital cataract
Infection such as Rubella is the most common cause of congenital cataract.
Intrauterine hypoxia/placental insufficiency
Pregnancy conditions such as the eclampsia or pre-eclampsia in which there is an increased level of high blood pressure, increased levels of protein, which results in decreased blood supply to the placenta and can damage the developing lens of the fetus, which can later cause cataract.
Cataract can develop during pregnancy when there is exposure of radiation such as X-rays, gamma rays and beta rays.
Taking steroid for a long period of time.
Diabetes Mellitus can lead to cataract due to the metabolic changes in our body.
most people have a positive family history of cataract which can be autosomal recessive and sometimes autosomal dominant as well.
Chromosomal disorder such as down Syndrome in which there is a strong association with cataract.
Metabolic disorder such as galactosemia, hypocalcemia and hypoglycemia and hyperglycemia can lead to nutritional deficiency of the lens and cause cloudiness of lens.
Trauma due to the process of delivery specially during forceps delivery can also cause cataract.
Causes of Acquired cataract
Aging is the most common cause of cataract in older population.
Eye trauma such as blunt eye injury or perforating eye injury can cause cataract.
Ultra violet, infrared, Ionizing radiations and microwaves.
Diabetes Mellitus, hypocalcemia, hypothyroidism and galactosemia.
Medications such as prolonged use of corticosteroids can result in the formation of cataract.
Disease like atopic dermatitis has association with development of cataract.
Patients with myotropic dystrophy may also develop cataract.
Disorder such as wilson disease, in which there is excessive copper deposition in the body, can result in the formation of cataract.
Diseases of the Bone
Patients with a condition known as osteogenesis imperfecta, has an increased risk of developing cataract.
Syndromes such as Down syndrome, Lowe’s syndrome, Miller’s syndrome, Rothman’s syndrome and Werner’s syndrome have been associated with the development of Cataract.
How cataracts are formed?
The factors mentioned above for example increasing age makes the lens less flexible, thicker and less transparent causing cataract. The lens is mostly made up of water and proteins. These proteins make the lens to appear transparent and when these proteins get clumped together it forms cloudy and opaque shadows in the lens, which is known as cataract. Acquired causes such as diabetes, trauma and drugs interfere with the normal activity of the lens, which results in the impairment of focusing ability (accommodation) of the lens and symptoms such as blurred vision, halos, double vision in one eye etc.
Complications of untreated cataract
The treatment of cataract involves removing the cloudy natural lens and replacing it with an artificial lens. If the cataract is left untreated, it can result in mild to severe vision threatening eye conditions. The development of the cataract with age being untreated can cause the following complications;
Inflammation of the eye
High eye pressure
Blurred near and distance vision
Double vision in one eye
Halos around light
Glare at night driving
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