Uniocular field of fixation

Question 1

Instruments/ target used

Answer 1

Lister Arc / 2° white or letter
Aimark / 1° or 3° light
Goldmann perimeter / smallest light that the patient can see with each eye (or cross in modified instruments Sullivan et al 1992).
Takagi projection perimeter
Octopus perimeter (automated)

Question 2

Method

Answer 2

he test is usually performed without glasses.
* The patient is seated at the perimeter with one eye occluded and chin on the rest of the same side as occluded eye. The height of the chin rest is adjusted until the eye is level with the central point of the perimeter. The head should be straight and remain still throughout testing.
* The target is moved away from the centre point and the patient asked to indicate when they can no longer look directly at the target. The target on some perimeters will be a small light – a letter is preferred by some clinicians as it is easier for patient to recognise when they lose foveal fixation. If you are using a light as the target, you should use the smallest light that the patient can see with either eye. Some clinics use the III4e light to standardise testing.
* The target is then moved back to the point where foveal fixation is regained and the patient feels they are looking directly at it.
* This point is plotted and the test repeated throughout 360.
* The points are joined up to show the range of the eye’s motility.

Question 3

Note

Answer 3

The examiner should observe the patient’s eyes to ensure that fixation is being maintained and that the eye is moving. The patient should not move their head during testing.

Question 4

UFOF measures (Duke- Elder 1973)

Answer 4

Duke-Elder (1973) reports that the uniocular field of fixation is 45° to 50° circularly around the fixation point except where this is restricted by the nose

Question 5

Muscles (Yashimoro 1957)

Answer 5

They found that the greatest excursion was on adduction, then abduction, followed by depression, followed by elevation.

Question 6

Aimark perimeter records

Answer 6

a greater degree of ocular rotation than the Goldman (Hanif et al 2014).

Question 7

Haggerty et al 2005 muscles

Answer 7

Haggerty et al (2005) suggest measuring along 6 axes only to represent the main direction of action of each of the muscles

Question 8

Interpretation

Answer 8

The direction of the field of movement will correspond to that of the examiner when viewing the result. Therefore, interpretation is straightforward.

Question 9

Automated measurement

Answer 9

The Octopus 900 may be used and has been compared to the Goldmann using speeds of 3°/sec and 10°/sec on the Octopus, with the latter producing a slightly larger field (Rowe and Hanif, 2009). However, this was not clinically significant and did reduce time of testing.

Question 10

Check list for UFOF testing

Answer 10

• Introduction: explain what the test is used for
• Hand hygiene and cleaning of the machine
• Patient set up: chin rest, no glasses, no AHP, appropriate target
• Set up chart
• Patient instructions
• Conduct test: every 30°, communicate throughout, moderate speed
• Complete chart details