Human vision and function/Part 3: Vision in real life: case studies/3.1 Nick Bastoni

Task 1

Nick Bastoni

Your first task is to look for material that describes “Myopia” or “Near-sightedness”, using the following broad headings:

1. Definition (with diagrams)
2. Aetiology (cause)
3. Treatment (glasses/lenses & laser corrective surgery, with diagrams)

Be sure to source diagrams of myopia to help you define it. The diagrams will become important later as we move further along in the case study.

There is a list of web-based resources on the previous page and these will help, but you might also find some on your own.

Compile the material you have found and post it on your group's discussion board. If you are unsure of a concept, you can also post your questions there. You should utilise the Problem Based Learning approach to this task and so your Group process should follow this patternː

1. Identify the patient's problem (You might not be able to do this immediately).
2. What do you already know? (Use the information from the web-site material).
3. Refine problem: what else do you need to find out?
4. Allocate information search to group members.
5. Pool information, discuss, answer identified problem.

Task 2

Nick Bastoni referral letter

Scenario

Youː

• are the orthoptist working at a rural Victorian hospital
• are employed in an ophthalmology clinic
• both you and the ophthalmologist travel to this clinic once a month and stay for 1 week

Nickː

• Nick Bastoni is a 14 year old
• He has been referred to the ophthalmology clinic for an eye assessment following a recent "Eye & Visual Assessment/Screening" carried out at the school by a local optometrist
• Nick's referral letter to the ophthalmology clinic contains 2 pages. Read it carefully.

Make some notes for yourself about what you do and don't understand on the referral letter. Discuss with your group what additional information you need.

Task 3

Consider the following questions with regards to Nick's case. Discuss each one in your group.

Remember previous readings by Kalloniatis M & Luu C (2014) Visual Acuity and the NDT Resource Centre. Review these when answering the questions below.

1. Was Nick's visual acuity normal?

a) The vision in his right eye is 6/12 (-3) and in his left is 6/9 (-3). What does this mean?

b) Use a diagram to describe his vision (for each eye) in terms of the visual angle subtended at the nodal point. Consider if you think he is myopic (near sighted) or hypermetropic (long sighted) and where the image would fall (before or after the nodal point).

You will find this video (Visual Acuity in 5 minutes) useful for answering your question.

2. The refraction result in Nick's referral letter indicates a change in visual acuity.

a) Firstly, consider what is refraction in the context of eye exams? This video on Subjective Refraction will help.

b) Does the change in Nick's refraction now give him normal visual acuity? What is his visual acuity after the refraction has been performed?

c) We use the notation '+' or '−' to describe the refractive power of lenses. This video Lens Box and Lenses shows you what impact each type of lens has on an object. Once you have watched it, decide whether a minus lens magnifies or minifies. Then consider how the '−' lens has changed Nick's vision. Use a diagram to help you explain it.

3. Updated scenarioː Nick has now been wearing his glasses for a month but can't manage with them when he wants to swim or play footy. He asks you about laser refractive surgery.

a) What is laser refractive surgery? Find your own resources but this resource from Web MD is a good starting point.

b) Explain how this process might relieve his need for glasses.

4. Return to Nick's referral letter, in particular the second page containing the Ishihara Colour Vision test result.

a) Describe which hue (colour) is most affected.

b) Describe how Nick's perception of colour will differ from someone with normal colour vision.

c) Discuss why, as a male, he might be more susceptible to this type of colour vision problem.

To help you with this section, you will probably need to go back to the Colour Vision topic in this subject. Don't forget to try the Ishihara test for colour blindness yourself as this will likely give you information about what is wrong with Nick. As always, use various resources to identify the problem and find the answer.

5. What is wrong with Nick's pupils?

The referral letter describes Nick's pupil responses.

a) What is the normal size of a pupil in average daylight/office/classroom conditions?

b) How should a normal pupil react to light and accommodation?

c) Could Nick's pupil response be explained by causes OTHER than the presence of eye disease?

Watch this playlist called "What is wrong with Nick's pupils". This will help you to answer a) and b).
You might need to find out more information though, to answer c). Try Better Medicine and Adolescent Health Curriculum to get you started.