- How does diabetes causes blindness? Is it reversible?
- What spinal reflexes can a person have after death? How is this possible? When do these reflexes stop working?
- Do people with lighter colored eyes have more red-eye in pictures?
- What is astigmatism? How do treatments for it work?
- How do the scuba masks with pink lenses work to make you see more colors?
- What limits the frequencies of sound that people can hear? How is this different than other animals? How does the structure of the ear differ among types of animals?
- Can you improve your reflexes?
- Are Q-tips bad to use in your ears? Why?
- Can cats really see in the dark? How? How are cats’ eyes different than peoples eyes?
- Does uv light (from the sun or a tanning bed) damage the eye?
Saturday, June 6, 2009
Lab 3 Quiz Bank Questions
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ReplyDeleteWhat is astigmatism? How do treatments for it work?
ReplyDeleteAstigmatism can be caused by an irregulary shaped cornea (corneal) or an irregularly shaped lense (lenticular). It usually occurs when the cornea is oblong rather than spherical. When the cornea is oblong, incoming light focuses on two spots in the back of the eye rather than one, causing blurriness. Astigmatism is usually hereditary, but may be caused by injuries that scar the eye.
Mild astigmatism can usually be treated with the help of corrective eye glasses or contact lenses.Severe astismatism may require the help of surgery.
Lee, J. & Bailey, G. (2008). Astigmatism. Retrieved December 2008, from All About Vision
Website: http://www.allaboutvision.com/conditions/astigmatism.htm
Answered By: Kristen H.
Scuba lenses:
ReplyDeleteWhen scuba diving the colors of the reef all appear in shades of blue, even though some of the coral are in reality very vibrant. Some mask companies such as ScubaPro have attempted to filter out the blue shades by making masks in tints of pink. This appears to help the colors appear brighter, but how does it really work? One study Cornea-Contact Lens Interaction in the Aquatic Environment attempted to explain how the color difference in mask lenses will actually affect the colors seen underwater. The study says that the blue shift is created because the water readily absorbs the shorter wavelengths even at shallow depths. Using a tinted mask may induce the eye to see longer wavelengths, though the study does not say how this is possible. When in air the shorter wavelengths are focused slightly before the retina and the longer wavelengths after. In water the longer wavelengths focused behind the eye become absorbed. With the tinted mask the shorter and longer wavelengths appear to be absorbed by the eye, as opposed to just the longer wavelengths of light.
Brown, MS and Siegel, OD. (1998). Cornea-contact lens interaction in the aquatic environment. Contact Lens Association of Ohthalmologist. 23(4):1-6. Retrieved June 8, 2009. Website: http://drmarkbrown.com/pdf/corneal%20topography.pdf
Allison Holder
How does diabetes cause blindness? Is is reversible?
ReplyDeleteDiabetes can cause blindness by developing diabetic retinopathy. It is when blood sugar levels are too high and it causes damage to the retina. In early retinopathy, the capillaries in the retina will develop weak walls and blood will escape from it and cause bleeding. If the fluid from the blood leaks out near the macula, area of retina for central vision, vision is dirupted. Over time, retinopathy will cause the capillaries to be closed off and block the oxygen to the retina, which will destroy parts of the retina. New blood vessels will then grow into these damaged parts but they will bleed into the vitreous gel, gel filled area in front of retina and over time the scar tissue from the bleeding will cause the retina to detach from the eye and vision will be lost. In severe retinopathy, the doctor may use laser therapy called scatter photocoagulation which minimize the growth of new blood vessels. Theres also medicines that slows down the growth of these blood vessels. If the retina is detached, a surgery called pars plana vitrectomy attempts to repair it but there is alot of risk involved. Blindness can be prevent if caught in the early stages of retinopathy.
Fong D, et al.(2004) Retinopathy in diabetes. Diabetes Care, 27: 84-87. Retrieved June 8, 2009. Website: http://www.svcmc.org/17417.cfm
Alex Hwang
Does UV light damage the eye?
ReplyDeleteUV radiation can cause both acute and chronic damage to the eye and skin. It is important to practice preventive medicine and inform the public of the risks involved in UV tanning. Patients are given UV protective eyeware for the tanning session, but in order to locate and turn the timer switch off, they must take off these goggles. This leads to hydrochlorothiazide-induced retinal phototoxicity, and studies have shown the presence of retinal lesions in both eyes. Hence, people should be aware of the harmful effects UV light has on the eye before using a tanning bed.
Costagliola, C. et al. (2008). Retinal phototoxicity induced by hydrochlorothiazide after exposure to UV tanning device. American Society of Photobiology, 84(5), 1294-1297. doi: 10.1111/j.1751-1097.2008.00404.x
Michelle Corrado
2. What spinal reflexes can a person have after death? How is this
ReplyDeletepossible? When do these reflexes stop working?
Spinal reflexes have only been observed in patients that have undergone brain death, which is defined as the “irreversible loss of function of the brain and brainstem” (Elliot). No electrical activity is present in these patient’s brains. The most commonly seen reflexes are deep tendon reflexes in the arms and legs and finger jerks. Also, abdominal reflexes, plantar flexor reflexes, toe flexion, shoulder adduction, back arching, and even a bilateral movement of the arm across the chest can be viewed. All of these movements are purely spinal reflexes, which do not require brain function. These reflexes can be observed immediately after brain death, especially in the first 24 hours. In almost all studies, all signs of movement were gone by 72 hours. If left alone with no life support, all brain dead patients will die in 24-48 hours, usually of heart failure, after which no movements occur.
Dosemeci, L., Cengiz, M., Yilmaz, M., & Ramazanoglu, A. (2004). Frequency of spinal reflex movements in brain-dead patients. Transplantation Proceedings. 36(1): 17-19.
Elliot, J. (2003). Brain death. Trauma. 5(1): 23-42.
Saposnik, G. MD; Bueri, J. A. MD; Mauriño, J. MD; Saizar, R. MD; Garretto, N. S. MD. (2000). Spontaneous and reflex movements in brain death. Neurology. 54(1): 221.
Michelle H.
ReplyDeleteAre Q-tips bad to use in your ears? Why?
Although Q-tips (cotton-tip applicator), provide to us more convenience to various things, including cleaning the ear. A specific cotton-tip applicator (Q-Tip)'s website however emphasizes the use of their product to the outside of the ear. Using this product in the ear, in proven experiments conducted, have been labeled the cause of otitis externa - an infection in the ear. This term is often called, "swimmers ear". People who suffer from this, suffer from dry itchy ears. This dryness allows for bacteria to invade and cause further damage.
Nussinovitch, Moshe. (2004) Cotton-tip applicators as a leading cause of otitis externa. International Journal of Pediatric. 68(4):433-435.
Do people with lighter colored eyes have more red-eye in pictures?
ReplyDelete“Red-eye” is a result of light from a camera flash being reflected to the camera lens from blood vessels in the retina. This happens in dark pictures because our pupils are dilated and the primary source of light is from the camera, close to the lens. The camera flash is so quick that the pupil has no time to respond by constricting. In outdoor pictures, light comes from the entire sky, so there is less light traveling back to the lens from the eye and the pupil is more constricted.
People with lighter colored eyes have more red-eye in pictures. This is due to the wavelengths of light absorbed and reflected, caused by the color of the iris which depends on the amount of pigmentation in the stroma. Brown irises are deeply pigmented, and thus absorb most of the light that enters it. Lighter colored eyes have a light pigmentation, and so only some wavelengths are absorbed while others are reflected back.
American Academy of Ophthalmology. Fundamentals and Principles of Ophthalmology: Basic and Clinical Science Course. San Francisco: American Academy of Ophthalmology, 1995.
Michelle Corrado
Can cats really see in the dark? How? How are cats' eyes different than peoples' eyes?
ReplyDeleteCats, unlike humans, have poor color distinction but very efficient night time vision. They accomplish this unique trait by having a large cornea, a slit pupil, and a tapetum lucidium. the large cornea allows for more light to enter the eye. Their distince pupil shape allows the cat's eye to dialate 6mm more than the human pupil and allows more light to enter when the surroundings are dark. This pupil also protects the retina from bright light damage. The tapetum lucidium, an adaptation that is not found in humans, is found behind the retina and reflect 130 times more light than the human's equivalent structure, the fundus. The lack of the tapetum lucidium is a reason why humans have red eye in pictures and cats do not.
Mitchell, Natasha. (2006). Feline opthamology part 1: examination of the eye. Irish Veterinary Journal. 59(3):164.
S.Mathew
Can you improve your reflexes?
ReplyDeleteThere are various factors that may slow one's reflexes, including the common reasons for such case such as lack of sleep, stress, and hunger. If improving the above conditions, reflexes will improve as compared to before.
Improving reflexes is highly probable. As people age, reflexes slow. Participating in habitual physical activities may improve reflexes as seen in Gauchard's research [1]. By having an experimental group preform physical activity, over a course of time, their balance improved as oppose to the control group.
A research proposed by Boot [2] provided the public further reasons for postive results of playing video games. It compared game playing users and non users, and resulted in game users surpassing non users in both visual and attentional skills, both showing skills preformed in lab.
1. Gauchard, Gerome. (2001). Physical and Spoting Activites Improve Vestibular Afferent Usage and Balance in Elderly Subjects. Gerentology. 47(5):263-270.
2. Boot, WR. (2008). The effects of video games playing on attention, memory, and extensive control. PubMed. 129(3)387-398.
the above post was Michelle Hwang.. in case :)
ReplyDelete