Human sense of Vision - Cataract

Cataract

A cataract is a condition that develops in the lens of the eye. Cataracts are made from a protein that has altered from its natural state (denaturation), distorting and eventually prohibiting required light from entering into the retina, the part of the eye that receives light. Often cataracts cause no problems for many years but as the cataracts matures the cloudiness increases on the lens, the light reaching the retina decreases and significant sight loss and perhaps blindness can result. Cataracts are considered a condition and not a disease therefore they develop for multiple reasons. Secondary cataracts develop from procedures preformed to correct other vision problems such as Glaucoma.

Traumatic cataracts develop from injury to the eye lens or the eye as a whole. Congenital cataracts are genetic and are found in babies and sometimes develop in childhood. There are also radiation cataracts that develop after some kinds of exposure such as excessive sunlight. It has been shown that cataracts can develop from long term use of certain steroids as well as some lifestyle habits. A cataracts can cover the eye lens partially or completely. It can be stationary, meaning its growth is in one place and slow or stopped, or it can be progressive and grow rapidly. Cataracts can also be hard or soft. In the case of any type of cataracts the procedure for treatment and eventually removal are similar.

Surgery

Cataracts surgery is one of the most progressive surgeries, having little or no side effects or post surgery complications. Cataracts surgery is the most common surgery performed on people over the age of 65, is covered by Medicaid and most medical insurance and the positive results are obvious within a week after surgery. Once a cataracts is removed it never comes back. Anatomy of a Cataract Within the lens, cataracts can form in any of the three layers of the lens; the capsule, the cortex or the nucleus. Cataracts which develop in the posterior subcapsular area are most often associated with diabetes and are the ones most likely to be found in a younger age group. This type of cataracts has also been linked to the long term use of corticosteroids, inflammation of the eye or eye associated trauma. In contrast, cataracts found in the cortical or nuclear areas are usually age-associated although there is a much higher risk of developing cortical cataracts when the eyes have been exposed excessively to damaging UV rays of the sun. Cataracts can develop in one or both eyes and there can be more than one type of cataracts that develops in the same eye. Over time, many individuals with a cataracts in one eye usually go on to develop a cataracts in the other eye as well. Cataracts are not painful, they do not cause the eye to tear abnormally and they are not known to make the eye itchy or red. There are three stages of cataracts ; immature, mature and hypermature. If an individual still maintains part of their vision, meaning the lens still has some clear areas, the cataracts is said to be immature. A mature cataracts is one which is entirely clouded over or opaque. Finally, a hypermature cataracts has begun to leak fluid from its hard outer capsule which may lead to problems with adjacent areas of the eye.

Symptoms of Cataracts :

The most common symptom of cataracts is the noticeable blurring and worsening of vision. Other symptoms include the dimming and fading of colors, decreased night vision, problems with bright lights and sunshine, and in many cases, regular visits to the ophthalmologist for changes in glasses and contact lens prescriptions as vision worsens. Some patients report double vision in the affected eye If an individual`s eyesight grows progressively worse, it is best to schedule a visit to an eye specialist as soon as possible. They will be able to assist with a diagnosis of the problem and available treatments if required. How do Age-Related Cataracts Form? There are two major ways in which age-related cataracts form. Protein clumping and yellowing of the lenses. In the healthy eye, the lens is mainly made up of water and a protein called crystallins. These proteins are thought to act somewhat like filters allowing the light to enter into the eye and become focused on the retina. There is little time for repair to the lenses as they are in almost constant use. As an individual grows older, some of the protein found in the lenses begins to degenerate and clump, or gather, together. The gathering of this material blocks some of the light that would normally enter through the lens and hit the back of the eye, the retina. A small amount of protein clumping may not affect the individual`s vision noticeably. However, when enough protein clumps in one area, the amount of light entering the eye is decreased and the eyesight becomes progressively more blurry and cloudy. The majority of age-related cataracts are formed in this manner. The current theory is that the protein of the lenses is damaged by free radicals which in turn causes the proteins to clump. Free radicals can be neutralized with antioxidants but many people have too few of these in their bodies to control the free radical assaults. Antioxidants are found mainly in fresh fruits and vegetables. The second method by which age-associated cataracts form is the result of a yellowing or browning of the normally clear, transparent lens. The discoloration of the lens is a common occurrence in most of the population as age increases and is usually the result of a breakdown of lens proteins which leave behind a yellow-brown pigment. The pigment tends to aggregate together and cloud the region of the lens. Unfortunately, in some individuals the discoloration of the lens may cause everyday tasks to become more complicated. Those who suffer from cataracts of this type tend to lose the ability to distinguish the colors of blue and purple. This category of cataracts does not seem to cause blurring of shapes. Some researchers have also pointed to the possibility that age-related cataracts may form due to low serum calcium levels. Nonetheless, in many cases, age-related cataracts have no identifiable cause.

Other Types of Cataracts Depending on the cause of the cataracts development there are several types, other than age-related cataracts, which have been defined. They are -

1.Secondary cataracts,

2. Traumatic cataracts,

3. Congenital cataracts and

4.Radiation cataracts.

Secondary cataracts can form following other eye problems. Examples include an eye that was previously treated for glaucoma or a different eye problem or disease. Health problems such as diabetes can also cause the formation of secondary cataracts. Additionally, the excessive or prolonged use of steroids, including medically approved steroids, has also been linked to the increased risk of secondary cataracts development.

In some individuals, cataracts may develop immediately or years after an event which causes damage to the eye. This is known as a traumatic cataracts and can occur due to blunt trauma to the eye or from exposure of the eye to alkaline chemicals.

A penetrating eye injury is associated with quick cataracts development. If a child is born with a cataracts it is known as a congenital cataracts. In some cases this inherited condition may be insignificant enough to not interfere with vision, in which case it is left alone. If the cataracts does cause vision disturbances in the child the lens of the eye may be removed and replaced with a synthetic lens. The gene causing cataracts is dominant, meaning that the child need only inherit the gene from one parent to develop the condition. Other sources of congenital cataracts are specific illnesses or infections that the mother has during pregnancy. Rubella and its associated metabolic disorder, known as galactosemia, both increase the risk of having a child with a congenital cataracts. Additionally, children can develop cataracts at a young age from any number of other causes and these cataracts are also said to be congenital.

The final category of cataracts is radiation cataracts. This type of cataracts may be caused from over exposure to ultraviolet sunlight and other forms of radiation. Population studies have actually concluded that exposure to sunlight over a prolonged period of time could double the risk of cortical cataracts. Interestingly enough, cataracts which form in the nuclear area of the lens were not shown to increase in occurrence from UV exposure. 11 Moreover, patients who are taking any medication which causes skin sun sensitivity should be aware that the medication will more than likely also increases the sensitivity of the eyes to the sunlight. Drugs of this type include, but are not limited to, some antibiotics, allopurinol (used in the treatment of gout), psoralen drugs (used to treat vitiligo and T-cell lymphoma), and phenothiazine drugs (used for mental and emotional illnesses). 11 Diagnosis In many cases, the diagnosis of a cataract is fairly simple. However, in the prenatal population, although diagnosis is possible it is a bit more difficult. Ultrasounds have proven an effective method to detect cataracts in unborn children. It is imperative that they be detected early if present as cataracts in babies can result in blindness for life if not treated properly and quickly soon after birth. 8 The most common way for an age-related cataracts to be diagnosed is during a routine eye exam. Since cataracts usually develop over a long period of time, in many cases they will not even be noticed by the individual if they are not causing any extreme vision changes. This is why it is so crucial, especially for the elderly, to have their eyes checked by a professional on a regular basis. During an eye exam, performed by an ophthalmologist or optometrist, there are several tests which may be administered to check for the presence of a cataracts.

Risk Factors :

In a majority of cases, cataracts form as individuals grow older. In fact, it has been suggested that by the time a person reaches 30 years old, the beginning stages of cataracts formation has already begun, although it may take up to another half a century for the cataracts to be fully developed and in need of medical intervention. Statistics show that by age 75, 70% of Americans may have cataracts which cause problems with everyday activities. Besides age, a second leading cause of cataracts is diabetes which is also the number one reason for blindness in adults between the ages of 20 and 74. Diabetes and obesity have both been associated with early onset of cataracts formation. The problem could possibly lie with the excess sorbitol, a byproduct of high blood sugar - glucose, found in the blood of diabetics. The sorbitol may collect in the lens of the eye and promote cataracts development. Although scientists are not positive on the relationship between obesity and cataracts, the fact remains that there is an increased chance of developing cataracts if an individual is overweight and, even more alarming, the risk doubles if the person is obese, as defined by a body mass index (BMI) measurement. 11 Other risk factors for the development of cataracts include lifestyle behaviors such as smoking and the excessive use of alcohol. Male smokers who go through 20 cigarettes or more per day have a two fold increase in their risk of developing cataracts and for women, smoking 35 cigarettes or more a day increases the risk by approximately one half. 11 More than likely, smoking raises cataracts formation risk due to the higher quantity of free radicals floating around in a smoker`s body. A second reason may relate to the inability of a smoker`s body to shuttle enough nutrients to the lens where they are used for proper, routine maintenance. Over time, without the correct minerals and vitamins, the lens (especially the proteins of the lens) begins to deteriorate. Long term use of corticosteroids has come under attack for its relationship to cataracts occurrence, too. In one particular study, 80% of patients on a prolonged treatment regimen of oral prednisone of 15 mg a day went on to develop cataracts. In the past, it was thought that inhaled corticosteroids were safe to use, however, a recent study published findings of a 50% increase of nuclear cataracts and a 90% greater occurrence of posterior subcapsular cataracts in those patients using inhaled corticosteroids versus the group not using the steroids. This study is especially important for asthmatic patients to take into account if prescribed inhaled corticosteroids. In many cases, however, the benefit-risk ratio must be studied by both patient and doctor. In a final note on corticosteroids, topical application to the eyelids and corticosteroid eye drops may also increase the risk of developing cataracts later in life. Injuries to the eye, also known as traumatic cataracts formation, can occur from blunt or penetrating trauma as well as exposure to alkaline chemicals. Sometimes cataracts will develop soon after the trauma and in other cases may not show up until many years later. Prior eye surgery has also been shown to increase the risk of cataracts formation. Those with a family history of cataracts run an increased risk of developing cataracts as do people that had developmental delays as a child, or were premature at birth. Being HIV positive, or of African-American heritage are both associated with a higher than normal risk of cataracts occurrence. Finally, prolonged exposure to UV light from sunlight or even from x-rays, can increase the chance of cataracts formation. This type of cataracts is known as a radiation cataracts.

1. A visual acuity test will measure how well the individual can see while standing at various lengths from the cue card.
2. A slip lamp exam uses a specialized microscope to increase the magnification of the eye. The specialist can then examine the eye in detail and up close.
3. A tonometry test is a standard test which measures the fluid pressure inside the eye. The major finding in this test, if an increased pressure is detected, is the possibility of glaucoma.
4. A dilated eye exam dilates the pupil. In this manner, the specialist is better able to view the lens to check for the present of a cataracts.

Conventional Treatment Options If a cataract is causing minor vision problems, many patients will opt to better their vision through glasses or contact lenses. Eventually, however, when and if the cataracts begins to have a greater impact on the quality of life of the individual, there is the option of surgery. Glasses and contact lenses are an option for many individuals in the beginning, before the cataracts develops into a major problem. There are various contact lens types to choose from and may be more convenient for people who have an active lifestyle, work outdoors in the elements or do not like how they look in glasses. For some individuals who have had eye surgery in the past, contact lenses are the preferred choice over glasses, as glasses sometimes produce uneven vision for these people. However, in terms of conventional treatment, glasses and contact lenses are only temporary fixes for a cataracts problem. Once the cataracts or cataracts worsen and the quality of life deteriorates, and the cataracts can no longer be improved through the use of glasses or contacts lenses, the only other option is conventional surgery.