Vision is an important part of everyday life. Mild to complete vision loss can make living a challenge. Retinitis Pigmentosa (RP) is an inherited condition that gradually tunnels field of vision and also leads to retinal degeneration. RP affects about 1 in every 3500 Americans (Openshaw, Branham, and Heckenlively, 2008). Living with RP is possible and people with RP can still have successful lives.
Mutations in at least 60 different genes can cause RP, in turn causing different forms of the disorder (“Retinitis pigmentosa”, 2015). The mutation can also be “influenced by the environment, or interactions with other genes (Openshaw et al., 2008)." There are three ways RP can be inherited, autosomal dominant, autosomal recessive, and X-linked inheritance.
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The disorder later causes blind spots in peripheral vision and soon the blind spots merge to form tunnel vision. After progressing over time, central vision can be affected. Many victims of RP reach adulthood legally blind (“Retinitis pigmentosa”, 2015). There are several ways to test for RP, three examples include a visual acuity test, electroetinogram (ERG), and fundas photographs. A visual acuity test puts a patient 20 feet away from a poster, on the poster are rows of random letters that get tinier after each row. The patient has to read out to the doctor what they think each row contains. This test determines visual accuracy, with a normal score being 20/20. 20/20 vision means one can see what a “normal” person sees at 20 feet. ERG tests “rod and cone function, and is important for confirming a diagnosis of RP (Openshaw et al., 2008).” Sometimes the ERG can show a patient RP is present before symptoms of the disorder are exposed. The test is limited to a few number of centers across the U.S. Fundus photographs use a special camera to “photograph the fundus, or back of the eye (Openshaw et al., 2008).” The eyes must be dilated for the procedure but the test is relatively fast (Openshaw et al., 2008). Complications of RP include cataracts, macular edema (swelling of the retina in the macular area), and in rare cases, vitreous floaters or hemorrhage (ASRS,
She tried to read row 6 feet that was 1.8 millimeters but could not see the rest of the letters. Next, I tested her right eye, however she could not see the row that was 15 feet, which was 4.5 millimeters she also mess up on a letter in row 20 feet. But with her vision test it suggested that her visual field are functioning fine. I held up 3 fingers and then held up two and she identifies what she had seen in her vision fields which she identified
There are three parts to the eye exam, the visual acuity exam. This test uses an eye chart to measure how good you can see an object details or the shape of an object at a far distance. 20/20 is the perfect visual acuity and if you 're legally blind than its worse than or equal to 20/200 in both eyes. The second exam is called the slit lamp exam which is a type of microscope that is used to examine the front part of the eye,, that includes the eyelids, conjunctiva, sclera, cornea, iris, anterior chamber, the lens, and part of the retina and optic nerve. The third exam is called dilated exam. Dilated exam is when drops are placed in the eyes to widen or dilate the pupil to enable your eye M.D. to examine the retina and optic nerve for signs of damage (“Diabetic Retinopathy
· genetics: occasionally the disease has a tendency to run in certain families (inherited or genetic predisposition), but this is not common.
Rossetti, Y., Rode, G., Pisella, L., Farne, A., Li, L., Boisson, D., & Perenin, M.-T. (1998). Prism adaptation to rightward optical deviation rehabilitates left hemispatial neglect. Nature, 166-168. pp. 166-168.
Age related macular degeneration (AMD) is the leading cause of blindness in people over the age of 50. Every ten years after the age of 50 the prevalence of this disease increases exponentially. Many different factors contribute to the development of AMD including genetic, environment, and metabolic functions. Aside from smoking, abnormal blood pressure, and an unhealthy diet low in fruits and vegetables, many more studies are concluding that similar inflammatory and oxidative processes seen in other age related diseases are also playing a key role in the development of AMD. This disease affects the central areas of the retina and choroid. In return central vision is impaired while peripheral vision is usually not lost. AMD is seen in two different forms, the earlier nonneovascular (dry) type and the more advanced neovascular (wet) type. Each form has its own specific pathology and unique characteristics that set them apart. Fatty, protein deposits called drusens may be the key risk factor in understanding dry AMD pathology, progression, and treatment. Once the more advanced wet AMD is diagnosed, pathology and treatment are targeted around the formation and destruction of abnormal blood vessels, characteristic of the wet AMD eye. The increasing prevalence of AMD has influenced more investigation into what factors can be modulated to prevent the onset or to stop the progression of AMD. Early diagnosis is very important because this is when an eye doctor can spot the early signs of the disease through ultrasound or angiography. This text will discuss the pathology of drusens and the role of inflammation and oxidation in the aged eye. By better understanding these processes more effective treatment approaches and preventive...
Lewis, Ricki, (2014), Human Genetics, 11th Edition, Chapter 12. Gene Mutation. [VitalSource Bookshelf Online]. Retrieved from
It is a rare condition that affects 2 % of Americans. Signs of pathological myopia include: Bending or distortion of straight lines, altered color perception, reduced contrast sensitivity, and increasing gloss of central vision. It is a quick severe progression of myopia and loss of vision is the end result. There is an increased risk of retinal detachment and other degenerative changes in the back of the eye (bleeding from abnormal blood vessel growth). If any of these things occur the risk of cataracts could increase. Treatment calls for a combination of a drug and a laser procedure called photodynamic therapy. It is reported to be the seventh ranking cause of legal blindness in the United States of America the fourth ranking cause in Hong Kong and the second in parts of China and Japan this form of myopia frequently progresses in adult life, with small intermittent steps of elongation being observable at any age. The adult progression appears to be due to the stretching of the walls of the eye. Genetically weak elements of the scleral wall are prone to thinning and stretching. One of the major forces at work in this stretching process appears to be the normal intra-ocular pressure (Ward
Some diseases that affect the retina and posterior segment of the eye include diabetic retinopathy, retinal cancer (melanoma), glaucoma, age macular degeneration, and uveitis. Diabetic retinopathy and glaucoma fall under diabetic eye disease. Diabetic retinopathy is the most common diabetic eye disease. It is the damage to the blood vessels in the retina. Gl...
There's a disease that lurks among young children even to this day. It's a direct result of a mutation in the genes that could result in the removal of the eye. Both boys and girls are affected, and one in every fifteen to thirty thousand babies is infected every year (Ambramson, Ch1). This eye corrupting, chromosomal abnormality shows up in about 300-350 new cases each year. It is called retinoblastoma.
Macular degeneration also known as late, aged-related maculopathy is an eye disorder which causes a decrease in the visual field known as the retinal macula (Medical Encyclopedia, 2000). The majority of people who are affected are people over the age of 65, but occasionally it develops earlier in people 40-50 years old (Philippi, 2000). The majority of the visual loss is located in the central part of the visual field, while the peripheral vision is unharmed. There are also two types of macular degeneration, the "wet" and "dry" forms. The "dry" form of this disease is the most popular, affecting 90% of the cases (American Academy of Ophthalmology, 1997).
Regarding to the ocular examination, the patient's visual acuity without optical correction (spectacle) was good 20/20 in both eyes. IOP measurements was 18 mmHg on the right eye and 16 mmHg in the left eye. The pupil was equal, round and reactive to light with no afferent pupillary defect in both eyes. In extarocular movement test, there was limited downward gaze with
For almost all types of Albinism both parents or mates must carry an albinism gene in order for their child to have albinism. Because the body has two sets of genes, a person may have normal pigmentation but carry the albinism gene. If a person has one normal gene and one albinism gene that is still enough to pass the disease on to their children. Even if both parents have the albinism gene it does not mean they have the sickness. The baby will have a one out of four chance of getting the disease. This is inherited by autosomal recessive inheritance.
The genetic defect that causes albinism in other types of albinism is unknown, but it is speculated that it involves other enzymes used to make pigment. Albinism is passed from parents to their children through genes. For nearly all types of albinism, both parents must carry an albinism gene to have a child with albinism. Parents may have normal pigmentation, but still carry the gene. When both parents carry the gene, and neither parent has albinism, there is a one in four chance at each pregnancy that the baby will be born with albinism.
... Blue color blindness is extremely rare, so rare that only five percent of color blind people suffer from it. The chance of having blue color blindness is equal in both men and women, as the gene is found on a different chromosome, chromosome seven. Red green colorblindness is usually found only in men. The gene that leads to Red green color blindness is found in the X chromosome. Color blindness isn’t constant in all countries and is more common in males than in females. For ethnicity it is more common in Caucasians/white people. Red- green color blindness affects ten percent of males in the United States, while only five percent of women are affected. 99% of all people with color blindness have Red-green color blindness. Overall color blindness effects a person’s life, but usually not severely, and it is more common in men than in women.
The images formed on the two retinas are so unlike that they cannot be blended in the brain. Thus, a double image is perceived. The condition is known as diplopia, or double vision. Prismatic lenses are prescribed to correct this defect.Imperfections in the cones of the retina, resulting from heredity or disease, cause defective color vision. This is known as color blindness, or Daltonism. In total color blindness, everything appears in shades of gray.