Contacts & Glasses
What is the difference between vision and learning disabilities? We will sort out the confusion surrounding these terms and help you get a better understanding.
Skin receives its color from cells called melanocytes. These cells produce a pigment known as melanin, which not only gives the skin its color, but also helps to protect it from the sun's harmful rays. When a person is unable to produce melanin, he or she may be diagnosed with a condition known as albinism. This is an inherited, congenital condition that comes in different forms as a result of several genetic variations and can affect both men and women, regardless of nationality or ethnic origin. Ocular albinism and oculocutaneous albinism are two of the most common forms of this disorder. Individuals with oculocutaneous albinism will have very minimal if any pigmentation, which results in skin that is very pale to pink, hair that is platinum or white, and sometimes exhibit a pink or lavender tint to the eyes. People with ocular albinism may have skin and hair that is close to normal in appearance, but their eyes lack melanin. Both forms of the disorder can result in complications with vision, although o culocutaneous albinism itself is commonly more recognizable than ocular albinism.
Visual Signs and Symptoms
There are a number of symptoms and problems that people with albinism may face. These problems include a lack of pigment in the eyes, photophobia, foveal hypoplasia, optic nerve misrouting, nystagmus and strabismus. Other vision problems such as astigmatism, farsightedness and nearsightedness will also have an effect on visual acuity. Although most people with albinism are able to see, they often suffer from reduced vision as a result of these eye conditions.
Minimal, or lack of, iris pigment is a major problem for people with albinism. Typically light enters the eye through the pupil while the iris, or the colored part of the eye, screens out excess light. When a person has little to no pigment in the iris, the light enters the eye unrestricted. This causes an extreme sensitivity to light, which is known as photophobia.
The lack of pigment often causes the eyes to develop abnormally, which results in many of the eye problems that are associated with albinism. At the back of the retina, th ere is a small area that is called the macula. The macula is what enables people to see objects clearly. At the center of this area is the fovea. When this is underdeveloped, it is known as macular or foveal hypoplasia and it will cause the person to lose some of his or her central vision.
Optic nerve misrouting is a condition in which the signals that are sent from retina to the brain are misrouted. This means that the signals do not follow the normal routes to the brain as they should. This is a symptom that is often indicative of albinism and is more of a brain condition than one that affects the eyes. For this reason, surgery is often not done as it would entail risky brain surgery.
A common condition that occurs with many congenital forms of vision loss is nystagmus. Nystagmus is best described as involuntary, rhythmic eye movements. As a result of this movement, vision is often impaired to varying degrees. In some cases, the nystagmus may worsen when the person is under extreme stress o r if he or she is tired. When this happens, it may cause the vision to fluctuate and worsen.
The inability to use both eyes together is also a common problem that occurs in albinism. When a person does not have binocular vision, or the ability to use both eyes together, it can result in a number of problems such as a lack of depth perception. A condition known as strabismus causes a person's eyes to not align correctly. This is often caused by a failure in the extraocular muscles to coordinate properly due to a muscle imbalance. When this occurs, a person may have eyes that are crossed, or an eye that deviates or wanders from the center.
In general, people with albinism have decreased vision with some form of refractive error that requires the use of eyeglasses or contact lenses. They will typically be farsighted (hyperopic) or nearsighted (myopic) and will also have astigmatism. People who are farsighted can see objects at a distance clearer than they can see objects that are closer. Farsightedness typically occurs because the eye is too short or the lens of the eye does not become round enough. In a farsighted eye the image, or light, that enters the eye focuses beyond the retina. When a person is nearsighted, he or she can see objects that are close, but has difficulty clearly seeing distant objects. A nearsighted eye is often longer, causing the image to focus in front of the retina instead of behind it. When a person has astigmatism, they are not able to see objects clearly because the light rays that enter the eyes will fall into two different places on the back of the eye. This is because the curvature of the eye is more oval than round.
Non-Visual Effect of Albinism
Albinism can effect people in ways that are not directly related to their vision. Because of the lack of melanin, people with this condition often suffer from severe sunburn if unprotected. To properly protect themselves, people with albinism should use sunscreen and wear appropriate protective clothing when outdoors. The risk of sunburn is magnified in certain locations, such as areas with high alti tudes or in areas that are near bodies of water or other reflective surfaces.
People with albinism may also have certain systemic diseases. These diseases are rare and may include Hermansky Pudlak Syndrome (HPS), Chediak-Higashi Syndrome (CHS), Prader - Willi Syndrome or Angelman Syndrome. Because their appearance stands out, it is difficult for people with albinism to not draw attention or stand out in a crowd. As a result this can cause emotional stress and difficulty. Mainstream media has often portrayed people with albinism in a way that gives the general public a negative impression. In film, people with this disorder are often portrayed as strange, frightening and evil.
Treatment and Low Vision Care
Despite the vision problems that are associated with albinism, there are steps that can be taken to care for one's vision and the comfort of their eyes. In terms of comfort, wearing protective lenses when outdoors will help reduce sensitivity and will protect the eyes from ultraviolet rays. A low vision specialist can help meet these needs by applying tints and special filters to block out the appropriate level of light for extremely photophobic eyes. In addition, sun protection for the eyes also includes wearing hats that help to block the sun from reaching the eyes.
To correct refractive error in terms of myopia, hyperopia and astigmatism, glasses or contact lenses are necessary. A low-vision specialist will perform a test called a refraction that will accurately measure the amount of refractive error. This will allow them to write out a prescription for the appropriate type of glasses. Often, bifocals are recommended for children in order to help reduce eyestrain associated with reading. Prescription contact lenses are another option that may even help to reduce nystagmus in some people with albinism.
Low-vision specialists are also able to help people with moderate vision loss to drive. This involves the use of a bioptic telescopic system and is known as bioptic driving. This bioptic system allows the driver to see signs and lights when driving. To be a candidate for bioptic driving, a person must not only meet certain visual requirements, but must also be able to use the bioptic properly and prove that he or she has adequate skills when driving.