Reference no: EM131409854

Assessment Instructions: The Special Senses

Part A -

John Smith is a 60 year old diabetic patient. He regularly attends the clinic where you are completing your placement. During a regular check-up, you notice that Mr. Smith is having trouble reading and is very sensitive to glare. On checking his file, it becomes evident that he has very poorly managed blood sugar levels and is also hypertensive. He is referred to an eye care specialist.

During a follow-up visit, Mr. Smith mentions that the specialist has diagnosed him with diabetic retinopathy. Mr. Smith doesn't understand how his long-standing diabetes can result in him potentially losing his sight and has asked him to help him understand the anatomy of the eye and how diabetes can affect the normal function of the eye.

Your task is to write a short essay to briefly explain the anatomy of the eye and how poorly managed diabetes can affect vision. Be sure to use language that Mr. Smith will understand; he has not studied science since high school. In you explanation you must include at least one (1) hand drawn labelled diagram that clearly shows the anatomy of the eye. The following must be labelled on your diagram: the optic nerve, optic disc, retina, iris, pupil, lens, suspensory ligaments and the cornea.

Details:

• As this is an essay, it should be written in correct sentences and paragraphs.
• Third person is preferable.
• Sub-headings should not be used.
• Additional diagrams may be used but these must be your original work (not copied from the internet or scanned from a text). They should be incorporated into the essay, not placed in an appendix. Referencing is essential.
• Please see FAQ at the end of this document for more details.
• Word Limit for the essay: 800 words.
• Remember that Turnitin will identify any copying from the Internet or other students. It will also identify copying from the textbook or study guide. Do not be tempted to plagiarise. University penalties apply.

Part B -

Complete the following tests on three subjects. Choose your subjects so that they represent a variety of ages and preferably include one subject aged less than 25 and one subject aged more than 50. 

After completing the practical tests, prepare a report that records your results and answers the questions below.

1. Test for near-point accommodation.

1. Ask the subject to close one eye.

2. Hold a pen vertically, 1m in front of the subject's open eye. Ask them to focus on the writing tip of the pen.

3. Slowly move the pen towards the subject until they can no longer see the tip in sharp focus.

4. Measure the distance from their eye to the pen tip at this point and record the distance in the table below.

5. Repeat for the other eye.

Question 1: How and why does near-point accommodation change with age? What is this condition called?

2. Test for visual acuity.

Visual acuity [sharpness of vision] is generally measured using a Snellen eye chart, which consists of letters of various sizes printed on a white card. The test is based on the fact that a letter of a certain size can be seen clearly by eyes with normal vision at a specific distance (20 feet). The distance at which a normal eye can see each line of letters is printed at the end of each line.

Visual acuity is reported as two numbers separated by a forward slash. The first number is always 20, which represents the subject's ability at 20 feet. The second number is the distance a person with normal vision would need to stand to read the same letters.

1. The chart provided here has been scaled to be used at 3 metre (10 feet) but the distance is reported in standard measures.

2. Stand the subject to 3 metres [10 feet] from the Snellen eye chart, with one eye covered by their hand.

3. Ask them to read each line aloud while you check for accuracy.

4. Record the number of the smallest line in which every letter was read correctly.

5. If the subject normally wears glasses repeat the test with and without their glasses.

6. Repeat for the other eye, this time reading the lines from right to left.

Question 2: Discuss how visual acuity is reported, using your subjects as examples where appropriate. Describe what it means if the number recorded is less than 20 (e.g. 20/15) or more than 20 (e.g. 20/40).

3. Demonstration of the blind spot.

(This test will be performed on yourself. You can also ask your subjects to do it if you wish)

1. Hold the figure below about 45 cm [18 inches] from your eyes.

2. Close your left eye and focus your right eye on the X which should be positioned so that it is in the centre of vision for that eye.

3. Move the figure slowly towards your face. Keep looking at the X. You will notice that the dot will suddenly disappear.

4. Turn the page upside down and repeat the procedure for your left eye. Note that everyone has a blind spot. If you do not see it the first time, repeat the procedure following the instructions carefully.

Question 3: What caused the dot to disappear? Why is the blind spot not normally obvious?

4. Test for Binocular Vision.

To demonstrate the importance of two-eyed (binocular) vision for depth perception, perform this simple experiment:

1. You will need a pencil and a small tube (1-1.5cm diameter). You could also use the barrel of a ball point pen and the cartridge inside it.

2. Hold the tube vertically and just less than an arm's length from your subject.

3. Ask them to quickly insert the pencil in the tube with both eyes open.

4. The subject must now remove the pencil and take it back close to their body. You should also withdraw the tube and then present it again in a similar (but not identical) position.

5. Ask your subject to close one eye and again try to quickly insert the pencil in the tube.

Question 4: Did your subjects find it as easy to insert the pencil with one eye closed? Why not? People with only one eye still have some degree of depth perception. Discuss three other cues that can be used to judge how far something is from you.

Attachment:- Assignment File.rar