Human vision and function/Part 3: Vision in real life: case studies/3.2 Sam Sinclair

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Task 1[edit | edit source]

Sam Sinclair

Your first task is to use the listed sites web-based resources on the previous page for material that describes “Cataract”.

Use the following headings to guide your reading:

  • Definition of "Cataract" (with diagrams).

You will find a lot of information that may go into too much detail. Please restrict yourself to general, broad information about senile cataracts only (look for FACT sheets).

This means those cataracts that occur SIMPLY as a result of getting older.

  • Risk factors (apart from simply getting older!)
  • What is the most common form of treatment? (Find some simple diagrams).
  • What is the effect of cataract in terms of it’s capacity to cause blindness, throughout the world? (Hintː check the WHO website).
  • Consider the rates of surgery performed throughout the world, by looking at WHO data from 2004.

Task 2[edit | edit source]


Sam Sinclair referral letter


  • 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


  • Sam Sinclair is a 75 year old
  • He has been referred for ophthalmic (eye) assessment following a recent eye examination by his optometrist
  • Sam is Nick's grandfather
  • Carefully read Sam Sinclair's referral letter.

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[edit | edit source]

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

1. Was Sam's visual acuity normal?

a) Use a diagram, to describe his vision (for each eye) in terms of the visual angle subtended at the nodal point.

2. Are Sam’s concern about losing his licence valid?

Hintː Check the VicRoads website for information about minimum visual acuity for driving.

3. Sam has cataracts

a) Describe what a cataract is, based on your previous investigations from Task 1 above.
b) What is the treatment for cataract?
This video might help you to answer question 3.

4. Waiting list for surgery.

When Sam sees the Orthoptist and Ophthalmologist they explain that the waiting list for cataract surgery is approximately 12 months, but suggest that if he can pay (out of his own pocket), for the first operation, he can wait for the other one to be done and pay nothing for that (as a public patient).

a) Try to find some estimates of costs for cataract surgery within the Melbourne metropolitan area.

5. Sam makes a decision.

Sam decides that he can afford to pay for the first eye himself, so the Orthoptist makes an appointment for him to have an A-Scan (axial biometry), so that the power of the Intraocular lens (IOL) can be calculated.

a) What is an IOL?
b) Why is it necessary?
c) How is it used in cataract surgery?

6. What is the prevalence & treatment rate of cataract estimated to beː

a) In Australia?
b) How does this compare with other countries?