Diseases and Disorders of the ear and eye - Assignment Example

Diseases and Disorders of the Ear and Eye Chapter 5 Critical Thinking Questions Diseases and Disorders of the Eye and Ear Howdoes the process of normal vision take place? Answer: The central physiology of vision revolves around light entering the retina from where a complex pathway of impulses through the optic nerves commences. From the optic nerve, the impulses reach the optic chiasma and then the optic tract. From there, they enter the lateral geniculate body. These impulses end in the primary visual cortex which lies in the occipital lobe via optic radiation. The brain perceives these signals and results in the object to be visualized by the eye (Guyton and Hall 2006, 640,641). 2. What are the four main errors of refraction? Describe each refraction error. Answer. The four main errors of refraction are presbyopia, hyperopia, myopia and astigmatism. Presbyopia refers to the reduction in the ability of the lens to accommodate objects with increasing age. It results in the inability to read very small words. Myopia which is also referred to as nearsightedness is an error of refraction in which the images of objects that are far are not formed on the retina. They are rather formed before reaching the retina. This is due to increased length of the eye. Hyperopia which is also referred to as farsightedness is characterized by the formation of the images beyond the retina. This is due to a shorter eyeball. Astigmatism is a complex error of refraction which occurs due to the presence of different powers of refraction along various planes in the eye. Cylindrical lenses are needed to correct this disorder (Riordan-Eva and Whitcher 2008, 387-389). 3. Explain the differences between nystagmus and strabismus? Answer. Nystagmus is a condition in which there is constant and oscillatory movement of the eyes. It may be restricted to only one eye. These movements of the eyes may be either in one direction or in all visual fields. Nystagmus may be physiological due to the stimulant effect on the semicircular canals of the ear or it may be pathological resulting due to brain lesions (Riordan-Eva and Whitcher 2008, 293,294). On the other hand strabismus is a condition which is associated with the non-alignment of the eyes while viewing an object. This means that at one particular instance, only one eye is focused at the object being viewed. This lack of alignment may be seen in all directions of vision (Riordan-Eva and Whitcher 2008, 229). 4. Differentiate between the two primary types of glaucoma. Answer. The two primary types of glaucoma include open angle glaucoma and angle closure glaucoma. A high intraocular pressure is characteristic of both the types. Open angle glaucoma has a greater frequency of occurrence and it is characterized by a gradual blockage of the drainage of the eye. The angle of the iris and cornea is open and not very narrow and thus it presents chronically. Angle closure glaucoma on the other hand is acute because of the narrowing of the angle that exists between the iris and the cornea. The intraocular pressure raises fast and thus it needs prompt correction (Glaucoma Research Foundation). 5. Explain the pathology involved in retinal detachment. How is this condition treated? Answer: The detachment of the neurosensory retina from its attachment to the retinal pigment epithelium is referred to as retinal detachment. Alteration in the mechanical and the metabolic forces which include the vitreous and adequate oxygen supply respectively results in this separation. When these forces are overcome, the retina becomes detached and results in the presence of subretinal fluid. This condition is treated by various methods which include scleral buckling, laser photocoagulation, vitrectomy and cryoprexy (Ghazi and Green 2002 411,412, 416). 6. Describe the three separate parts of the ear. Answer: The three separate parts of the ear are external ear, middle ear and inner ear. The external ear comprises of the auricle, the auditory canal and the drumhead. The middle ear is made up of the ear tube, the mastoid and its ear cells. The inner ear comprises of the bony labyrinth and the membranous labyrinth. The external ear is mainly involved in receiving sound impulses and transmitting it forward. The middle ear is also a conduction system. The inner ear has a greater role and is involved in both listening as well as the maintenance of balance (Dhingra 2009, 3-12). 7. What symptoms may an individual with Ménière disease experience? Answer: A patient with Meniere’s diseases experiences symptoms of vertigo, loss of hearing, noises being heard in the ear in the absence of any actual sounds as well as pressure build up in the ear. Vertigo may be episodic and go on for as long as two hours and may be accompanied with nausea. The patient may complain of hearing ringing or buzzing sounds. The patient may also present with having a sensation of raised pressure inside the ear (Mayo Clinic Staff 2012). 8. Precisely define otitis media. How is it classified? How is it diagnosed? Answer: The inflammation of the middle ear is referred to as otitis media. It is classified as acute otitis media, otitis media with effusion in the ear and chronic suppurative otitis media. The diagnosis is done by using typanometry, otoscopy and reflectometry. The main signs of this condition include a bulge and cloudy appearance of the tympanic membrane. The lack of movement of the tympanic membrane is another sign (Ramakrishnan, Sparks, and Berryhill 2007, 1650,1651,1652). 9. What is myringotomy? Answer: Myringotomy is a surgical approach whereby the tympanic membrane is incised. This is done to remove the fluid accumulated in the middle ear which may be infective or non-infective. This is also done to correct a faulty Eustachian tube so that it receives air. The procedure is carried out mostly under general anesthesia. It is contraindicated in patients suffering from a glomus tumor within the tympanic membrane (Dhingra 2009, 355). 10. Name the etiologic factors of macular degeneration. Answer: Macular degeneration is mainly an age related pathology which results in complete loss of vision in developed nations. Although no definite causes for the condition have been identified but smoking of cigarettes, raised blood pressure and genetics are known to play a role (Alfaro 2006, 23). References Alfaro, D. V. (2006). Age-related macular degeneration: A comprehensive textbook. Philadelphia: Lippincott Williams & Wilkins. Dhingra, P. L. (2009). Diseases of ear, nose and throat. New Delhi: B.I. Churchill Livingstone. Ghazi, N. G., & Green, W. R. (January 01, 2002). Pathology and pathogenesis of retinal detachment. Eye (london, England), 16, 4, 411-21. Retrieved from http://www.nature.com/eye/journal/v16/n4/pdf/6700197a.pdf Glaucoma Research Foundation. (2013). “Types of Glaucoma.” Retrieved from: http://www.glaucoma.org/glaucoma/types-of-glaucoma.php Guyton, A. C., & Hall, J. E. (2006). Textbook of medical physiology. Philadelphia: W.B. Saunders. Mayo Clinic Staff. (2012). “Diseases and Conditions: Meniere’s Disease.” Mayo Clinic. Retrieved from: http://www.mayoclinic.org/diseases-conditions/menieres-disease/basics/symptoms/con-20028251 Ramakrishnan, K., Sparks, R. A., & Berryhill, W. E. (January 01, 2007). Diagnosis and treatment of otitis media. American Family Physician, 76, 11, 1650-8. Retrieved from http://www.aafp.org/afp/2007/1201/p1650.pdf Riordan-Eva, P., & Whitcher, J. (2008). Vaughan & Asburys general ophthalmology. New York: The McGraw-Hill Companies. Read More