Eye Pathology Related To Albinism, Research Paper Example

Albinism is a general term used to define a variety of genetic disorders effecting skin, hair and eye pigmentation.  There are two basic categories of albinism.  Oculocutanious albinism (OCA) is a condition presented by the complete or partial absence of a pigment called melanin.  Melanin is responsible for pigmentation in the skin, hair and iris.  With the exception of eye problems and skin conditions (such as cancer) resulting from the lack of pigmentation, individuals with albinism typically enjoy normal growth and physiology.

Since albinism is typically precipitated by recessive genes, a parent who has albinism can usually expect to have normally pigmented children unless married to another person with albinism.

While there are a large number of subcategories and syndromes associated with the disorder, there are four basic categories of OCA.  Type 1 OCA is presented by a complete absence of melanin.  The skin and hair are entirely white with no splotching or freckles.  The iris lacks pigmentation and is thus transparent.  This transparency allows the capillaries in the eye to be visible, rendering the iris red in color.  There are numerous subtypes within this designation depending on the combination of characteristics and symptoms.

Type 2 OCA is presented by decreased melanin but not a total absence.  This shortage of melanin can vary from person to person.  In some cases the resulting appearance of people with Type 2 OCA may only be apparent by comparison to their parents.  More common in black people than in white, Type 2 OCA may result in a person still having most of the characteristics of other family members, but lighter in skin or eye color than the rest.  Both Type 1 and Type 2 OCA individuals tend suffer with nystagmus – an involuntary jumping or twitching of the eye.

Type 3 OCA is typically found in black South Africans and is presented by reddish/brown skin, light brown or hazel eyes, and red hair.  Type 4 OCA is mostly found in Japanese people and is similar to Type 2 OCA (Alan, 2009).

Another type of albinism is called ocular albinism (OA).  OA is characterized by eye-related problems with little or no changes in skin or hair pigment.  Persons with OA present with a number of optical issues including congenital nystagmus (involuntary eye movements), hypopigmentation of the ocular fundus (lack of pigment in the inside back portion of the eyeball), (also known as foveal hypoplasia, the underdevelopment of the macula – a small area of the retna that helps with seeing fine detail), photophobia (an extreme sensitivity to light) and impaired vision due to refractive errors (Rosenberg & Schwartz, 1998).

There is also a condition known as piebaldism.  This condition is sometimes called “partial albinism.”  This condition presents with splotchy skin whereby pigment is unevenly dispersed throughout the skin and hair.  Individuals with this condition seldom have the vision problems typically associated with full albinism.

All types of albinism are relatively rare, with an overall worldwide occurrence of about 1:20,000.  The rate of occurrence of OCA progressively increases from Type 1 (1:40,000) to Type 3 (1:8,500).  OA (primarily affecting the eyes) occurs at a worldwide rate of about 1:50,000.  OCA is an autosomal (non-sex-related chromosome) recessive disorder usually related to two defective alleles.  OA can be caused by autosomal recessive, X-linked recessive or autosomal dominant forms with the most common being the X-linked variety (Schub, 2010).

Physiological Changes of the Eye

Physiological issues affecting the eye are found in individuals with OA and OCA Types 1 & 2.  The most common eye-related issue is congenital nystagmus.  This condition causes the eyes to involuntarily jerk or twitch.  These movements tend to be mostly horizontal although some other directional movement can occur.  These movements also tend to be rhythmic and stimulated by head movement or the amplitude of visual stimulation (Curtis, 2010).  Rhythmic eye movements are also noted in the sleep state.

In some cases of nystagmus, the eyes continually sweep from one side to the other as if the person were scanning the horizon.  In other cases, the person’s eyes begin by being focused on a given object.  The eyes slowly drift to one side, then snap back to the object of focus.

Iris translucency typically occurs with Types 1 & 2 OCA and is the result of a complete lack of melanin.  Individuals with this condition appear to have red iris color.  There is actually no color in the iris.  The red appearance is due to a clear view of the individual’s capillaries.

Hypopigmentation of the ocular fundus is most common among people with Type 1 albinism.  This condition is presented by the lack of pigment in the retina.  Since there is no pigment in the back wall of the eye, chorodial blood vessels can be clearly seen.  It is this condition, coupled with Iris translucency that makes the iris appear red in color.

Macular hypoplasia is a genetic defect whereby the macula is underdeveloped.  This condition does not present any observable physical symptoms, but is a significant contributor to poor vision.  The macula is the part of the eye responsible for detailed vision.

Photophobia is caused by a severe aversion to sunlight or bright artificial light.  Unlike most phobias, photophobia is not a morbid condition precipitated by an unreasonable fear.  There is no psychological basis for this phobia, For a person with photophobia, the aversion to bright light results from actual pain or discomfort resulting from the lack of pigment throughout areas of the eye.

Impaired vision from refractive errors can also be found in people with albinism.  The two most common types of refractive disorders are hypermetropia and astigmatism (Rosenberg & Schwartz, 1998).  Also known as hyperopia (or far-sightedness), hypermetropia is a condition where light rays entering the eye are not properly bent to converge directly on the retina.  In a far-sighted person, the light rays are focused to a point behind the retina.  This misalignment of focus causes difficulty in seeing near objects (such as a book) clearly.

Astigmatism is caused by an irregularly shaped cornea.  If the cornea is shaped like a football rather than a basketball, the eye will focus vertical and horizontal images differently.  If for example a person with astigmatism were to look at an image of a plus sign (+), either the X axis would be in focus while the Y axis would not, or visa-versa. In either case, the eye will attempt to equalize focus on both the X & Y axis rendering neither axis clear, and the entire image blurry.

Functioning of the Diseased Eye and Effect upon Vision

Nystagmus is presented by rhythmic, involuntary eye movements – usually from side to side. A person with nystagmus is unable to maintain a constant focus on a given object.  Given that the eyes are constantly moving, it is almost impossible to see a single object clearly.  This condition can cause nausea, headaches or vertigo.  The best hope of focusing on a given object is to turn the head as if looking all the way to the right or left.  Turning the head and looking out of the “corner of the eye” reduces the travel of the eye twitch.  This position is called the null spot or null position (Dubow, 2010).

According to Treacey (2009), children with Nystagmus and other related optical problems have a higher rate of ADHD than “normal” children.  These children find it difficult to visually focus on learning materials which causes them to disenfranchise themselves from overall classroom and social experiences.  In essence, they cannot visually “connect” with what they see thus they tend to be less likely to connect with teachers, other children and even non-visual aspects of the learning experience.

In these cases, a child with albinism’s visual problems results in socialization, emotional and psychological difficulties.  Children who are rejected by their peers may develop a number of psychological disorders such as PTSD or associative identity disorder.

Another significant problem for individuals (even adults) suffering from nystagmus is social stigma.  Holding a conversation with another person generally involves some degree of body language, including eye contact.  Speaking with an individual whose eyes are constantly moving can be disquieting and for many people and in some cases, worthy of avoidance.

Iris translucency can result in several functional problems.  In a normal eye, light enters the eyeball through the pupil.  The cornea refracts, or bends light rays entering the eye through the pupil opening into a singular focus on the retina for interpretation by optic nerves.  When the iris is transparent, light rays enter the eye with perfect clarity through the pupil, while bits of light also enter through the translucent iris surrounding the iris.

Since the iris is not as perfectly clear as the pupil, light rays are partially defused – much as the light entering a bathroom through a textured glass window.  This defused light is scattered throughout the inside of the eyeball and tends to confuse the optical nerves.  People with Iris translucency can experience diminished ability to focus, diminished color differentiation and sporadic “light flashes” known as visual scattering (Shen, Samaraweera, Rosenberg, & Orlow, 2001).

Another problem with iris translucency is hypersensitivity to light resulting in photophobia.  People with this problem can experience mild to extreme pain in bright-light situations.  This pain can cause acute pain in the eye itself as well as headaches.

Coupled with hypopigmentation of the ocular fundus, iris translucency can make a person’s iris appear red in color.  This appearance can also cause social acceptance problems.  Most forms asking for eye color include blue, brown, green, grey or hazel as options.  Red is typically not an option because red pupils are not common.  People with physical characteristics that are uncommon are often stared at or avoided making this condition an impetus for social bias.

The lack of melanin not only produces changes in the eye’s physical appearance and visual performance, but is also noted to affect overall optic development.  According to Shen, Samaraweera, Rosenberg, and Orlow (2001), the lack of pigment can also have an effect on neurogenisis relating to the eye.  Optic fibers can become “misrouted” in people with this condition.

Macular hypoplasia is the underdevelopment of the macula – the part of the eye that focuses on fine detail.  This condition can cause blurred vision as well as myopia and corectopia.  Myopia is a condition where distant objects are blurry.  Corectopia is presented by pupils that are not properly centered within the iris.  Instead, the pupil is off-centered, focusing the incoming image on the wrong part of the retna which makes focusing on a given object difficult.  Both of these problems can have profound effects on visual acuity.

Photophobia precipitated by lack of pigment is probably the least problematic symptom of OA.  People suffering from this condition typically manage it by avoiding bright lights or by wearing sunglasses.

Hypermetropia (far-sightedness) and astigmatism are not conditions that are exclusive to individuals with albinism.  These conditions are fairly common among the general population.  The causal factors, symptoms and medical remedies for people with albinism are mostly the same as they would be for any other person.

Methods of Treatment

Both OCA and OA are genetic disorders.  There are no cures for either.  There are however, treatments that can address the symptoms of many of the optical affections suffered by people with OCA or OA.

Nystagmus cannot be treated to completely eliminate involuntary eye movements.  Symptoms can sometimes be reduced using eyeglasses with prisms.  The prisms on these glasses force the eyes to always look in the null position.  This effect can also be created through eye muscle surgery.  In this surgery, the eye muscles are tightened in the direction of the individual’s null position causing subsequent eye movements to be less dramatic (Schub, 2010).

Treatment options for macular hypoplasia are extremely limited.  Some who suffer this condition opt for wearing a patch over the better eye.  In cases where there is hope of optical improvement, forcing the weakest eye to “do all the work” is thought by some to assist in strengthening the optic fibers in that eye.  Patching is not a permanent treatment, but is practiced until the weak eye equals the strong eye in function.

Another condition associated with macular hypoplasia is strabismus – a condition whereby one eye looks straight ahead while the other looks off in one direction or another.  Surgery can mitigate this condition but with limited results.  It is almost impossible to properly align both eyes to produce normal stereoscopic focusing.  This surgery is typically conducted for its psychosocial results.  Individuals suffering from strabismus often want to appear to others to be more normal even though the visual benefits may be limited.

Iris translucency and hypopigmentation of the ocular fundus are neither curable nor treatable on an organic level.  Some individuals who suffer these conditions wear opaque or dark translucent prosthetic iris devices (contacts).  Opaque contacts can reduce photophobia as well as the “scattering” of light entering the eye.  Dark translucent contacts may provide a more natural appearance, but are not as effective from a physiological perspective.

Photophobia cannot be cured or treated.  The pain and discomfort symptoms of photophobia can be reduced by wearing opaque contacts or dark sunglasses.  Individuals with this condition cal also equip their homes and workplaces with low wattage lighting.

Refractive conditions such as hypermetropia and astigmatism can be treated through conventional ophthalmologic means.  Hypermetropia has traditionally been treated with glasses or contacts.  In recent years advances in technology have allowed many to pursue the increasingly affordable Lasik treatments offered by optometrists.  Unless the condition is severe, astigmatism can be treated with tri-focal glasses or contacts.  These devices focus lateral and horizontal images differently thus compensating for the odd shape of the effected eye(s).

Prognosis

Eye conditions suffered by individuals with OCA or OA are for the most part, permanent and not curable.  The most that such a person might hope for is to mitigate some of the symptoms associated with these conditions.  In the best cases, some remediation may be experienced through surgical procedures.  Conditions associated with OA have no direct impact on intelligence, mental health or other physiological factors.  While this fact may be medically relevant, it does not affect the perception of individuals with OA by others in society.

Unfortunately the prognosis for a happy life for someone suffering from albinism is not as good as a typical person with another disability such as blindness.  The fact that a person with albinism cannot see properly is for many, the least impactful on their quality of life.

There are many stigmas associated with albinism.  This condition is so vastly evident, and those who suffer from it so vastly different from “normal” people that it is often difficult to engage in normal socialization processes.  Since every person with albinism is born with this affliction, each must survive the rigors of childhood.

Children are not known for being particularly altruistic or considerate of the feelings of others.  Children who are even the slightest bit different (e.g. too short, too tall, too fat, too thin) are often teased by their peers.  A child with albinism is far beyond “the slightest bit different.”  He or she is vastly different.  White skin, white hair, red eyes, or eyes that continually twitch, or eyes that both stare in different directions are a mountain of fodder for insensitive juveniles.  It is no wonder that so many children with albinism develop ADHD or become antisocial.

Even adults that suffer this condition can find life challenging.  Social bias is unfortunately not reserved for children.  The reason that the United States has EEOC laws and equal housing laws is because many individuals still tend to apply their bias against others who are different to their professional and business decisions.

Growing up and living in a society where conformity is king can be difficult for a person who looks like no other person in town.  People with albinism must continually abide the stares of others and the host of finger pointing by kids.

To imagine how it must feel to endure this social stigma, one might imagine dying ones skin green and walking through a mall – or trying to get a job – or finding new friends.  Couple this with an obvious disability like having red eyes and a person might begin to understand the challenges faced by people with albinism.

The physical challenges endured by individuals with OCA or OA are only the beginning of their quest for quality of life.  Visual problems are difficult and produce a unique set of challenges.  When these challenges are coupled by social rejection and bias, the quest for quality of life becomes even more difficult.

References

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(Curtis T 10 EMedicine)Curtis, T. (10). EMedicine. Retrieved from http://emedicine.medscape.com/article/1200103-overview

(Dubow B 2010 All about vision)Dubow, B. (2010). All about vision. Retrieved from http://www.allaboutvision.com/conditions/nystagmus.htm

(Rosenberg T Schwartz M 1998 X-Linked ocular albinism; Prevalence and mutations – a national study)Rosenberg, T., & Schwartz, M. (1998). X-Linked ocular albinism; Prevalence and mutations – a national study. Eurapean Journal of Human Genetics, 6, 570-577. Retrieved from http://web.ebscohost.com.ezproxy.apollolibrary.com/ehost/pdfviewer/pdfviewer?vid=3&hid=106&sid=68fcd074-6a90-4fe2-9c6d-78df5f1edf17%40sessionmgr113

(Schub T 2010 CINAHL Nursing Guide)Schub, T. (2010).  In CINAHL Nursing Guide (March 12 ed.). Retrieved from http://web.ebscohost.com.ezproxy.apollolibrary.com/nrc/detail?vid=6&hid=107&sid=501437c0-98a8-4c97-9c65 08cefc0c4d7e%40sessionmgr113&bdata=JnNpdGU9bnJjLWxpdmU%3d#db=nrc&AN=5000003088

(Shen B Samaraweera P Rosenberg B Orlow S 2001 Ocular albinism Type 1: More than meets the eye)Shen, B., Samaraweera, P., Rosenberg, B., & Orlow, S. (2001). Ocular albinism Type 1: More than meets the eye. Denmark NLM, 14(4), 243-248. Retrieved from http://web.ebscohost.com.ezproxy.apollolibrary.com/ehost/pdfviewer/pdfviewer?vid=3&hid=106&sid=68fcd074-6a90-4fe2-9c6d-78df5f1edf17%40sessionmgr113

(Treacey A 2009 Eye for the unusual)Treacey, A. (2009). Eye for the unusual. Minisoda Medicine, June(2009), 8-10. Retrieved from http://web.ebscohost.com.ezproxy.apollolibrary.com/ehost/pdfviewer/pdfviewer?vid=3&hid=109&sid=b746962c-8970-437b-8eb0-1ff0efdf2941%40sessionmgr113