What happens with a patient who develops a cataract?
A cataract is the opacification of the crystalline lens in the eye. In a patient with cataract, there is progressive loss in the transparency of the crystalline lens; this is due to changes in the density of the epithelial cells. There is also a derangement in the fiber of the lens cells. Lens transparency can also be because of deposition of minute epithelial masses of apoptotic lens tissue in the substance of the lens leading to disruption of the internal homeostatic mechanism of the lens and accelerating the process of cataract formation. (Vincente Ocampo, 2012)
Cataract initially leads to an increase in the power of the lens leading to myopia. Thereafter, increased yellowing and opacificcation of the lens leads to reduction in the ability to perceive blue colors. There is gradual loss of vision and this can eventually lead to total blindness. Senile cataract is the most common form. it is characterized by initial opacification of the lens, followed by progressive swelling and eventual shrinking of the lens accompanied by complete loss of transparency of the lens. continued contraction of the lens can lead to its rupture, giving rise to a severe inflammatory reaction.
How does cataract formation represent a variance from normal anatomy & physiology?
Cataract represents a variance from the normal anatomy and physiology because the crystalline lens is meant to be a material that freely allows light to pass through so that an image can be formed on the retina (Paine, 2012). However, with the presence of particles in the lens already, these particles are superimposed on any image formed on the retina. Most times, the deposited substances are whitish in color, the resulting image formed on the retina is perceived by the individual as a cloudy image. Therefore, patients with cataract complain of cloudy vision. In addition, since the process is a progressive one, the size of the deposited particle increases, the degree of cloudiness of vision also increases over time, up to a point when the whole of the crystalline lens is completely filled with these particles and the individual goes blind totally (Paine, 2012).
What happens in sensorineural hearing loss?
Sensorineural hearing loss is a hearing defect in which there is no defect with the process by which sound reaches the inner ear from the exterior but the individual is still unable to process the auditory information correctly (Kathleen Romito, 2009). This is because there is a problem from the level either of the inner ear or along the pathway to the brain. With this explanation, it is clear that there is no problem with the perception of the stimulus from the external environment. The problem however lies in the conducting of the stimulus from the sensory organs of hearing, along the neural transmission to the central auditory processing unit in the brain (Stephanie Antonio, 2009).
How does sensorineural hearing loss represent a variance from normal anatomy & physiology?
The normal pattern of hearing is for the stimulus, sound to be perceived as a stimulus from the external environment and the sound conducted to the sensory organs of hearing. From here, the signal is transduced from sound waves into electrical stimulus that can be conducted by nerves. The nerves transmit the impulse to the brain for interpretation (Stephanie Antonio, 2009).
There is a deviation from this norm because there is a problem from level of the transduction of the sound waves to electrical impulse to the brain (Kathleen Romito, 2009).
References
Stephanie, Antonio (2009). Syndromic Sensorineural Hearing Loss. Medscape reference: Drugs, Diseases & Procedures. <http://emedicine.medscape.com/article/856116-clinical#showall>
Kathleen, Romito (2009). Sensorineural hearing loss. emedicinehealth. <http://www.emedicinehealth.com/script/main/art.asp?articlekey=137575&ref=128011>
Vincente, Ocampo (2012). Senile Cataract. Medscape Reference: Drugs, Diseases and Procedures. <http://emedicine.medscape.com/article/1210914-overview#showall>
David, Paine (2012). Cataracts. emedicinehealth. <http://www.emedicinehealth.com/cataracts/article_em.htm>
