Practical 1: Drugs on the Eye

Question 1

Outline the method of this practical

Answer 1

• work in groups- 4 volunteers, 2 experimenters (A-G)
• Each of the 4 volunteers given the following drugs: Phenylephrine, Pilocarpine, Tropicamide, Tropicamide and Pilocarpine
• Take control measurements for eye 8. Measure- Pupil size, pupillary response to light, near point, near vision and far vision
• Add eye drops by tilting head back and pulling lower lid backward, dropping into lower lid. Avoid blinking to minimise drainage into the naso-lacrimal duct. In the 2 drug subject, put the second drug in the same eye
  Take measurements again after 5 minutes, then every 10 minutes after

Question 2

What apparatus is used for measurements? (5)

Answer 2

• Pupil Gauge
• Pen torch
• Near-point rule
• Reading books
• Snellen test chart

Question 3

What does the pupil gauge measure?

Answer 3

Pupil size

Question 4

How do you assess your own pupil size?

Answer 4

Use plastic coated in black film. Hold up against one eye and move across face until the 2 holes become separate entities- note down the number (mm)
Repeat with other eye

Question 5

How do you assess your colleague’s pupil size?

Answer 5

Use piece of perspex with holes punched in it. Hold in front of eye and move across until hole size matches pupil size and note (mm)
repeat with other eye

Question 6

What does the pen torch assess?

Answer 6

Pupillary response to light

Question 7

How do you use the pen torch to assess pupillary response to light?

Answer 7

Shine briefly in each eye and record whether or not the pupil constricts and whether this is fast or slow

Question 8

What does the near point rule measure?

Answer 8

Near-point vision

Question 9

How do you use the near point rule to measure near point vision?

Answer 9

• Place on bridge of nose
• close one eye
• move block to to the far end and move towards eye until the words/numbers blur- read off the number and record (cm)
• repeat with other eye

Question 10

What do reading books measure?

Answer 10

Near vision

Question 11

How do you use reading books to measure near vision?

Answer 11

• Hold book 30cm away from face and close one eye
• look through the passages until you find the smallest you can comfortably read
• record
• repeat w. other eye

Question 12

How do use use the Snellen test chart to measure far vision?

Answer 12

• stand 6m away
• covering each eye determine the smallest line of letters you can read correctly
• record

Question 13

What does the Snellen test chart measure?

Answer 13

far vision