Anisometropia and Aniseikonia

Question 1

How can aniseikonia be tested (measured)?

Answer 1

Use prism to separate images and then use size lenses to make images equal size (size of size lenses tells you the difference between the image sizes)

Question 2

When does aniseikonia become clinically significant?

Answer 2

When it causes a barrier to sensory fusion

Question 3

What happens when the difference in image size is 0.75-2.5%?

Answer 3

Eyestrain from attempted maintenance of fusion (still clinically significant)

Question 4

What happens when the difference in image size is 2.5-4%?

Answer 4

Poss fusion attempt
Suppression
Poss symptoms

Question 5

What happens when the difference in image size is >4%?

Answer 5

Suppression very likely as BSV not possible

Question 6

What are the possible causes of aniseikonia?

Answer 6

Retinal (macula pathology, change in PR spacing)
Neural (interpretation of differing sizes but retinal size the same, or correction causes due to adaptation)
Optical (refractive component difference, axial length difference)

Question 7

What are the possible causes of anisometropia?

Answer 7

Refractive component difference (more likely if diff under 2D)
Axial length difference (more likely if diff over 2D)

Question 8

What are the possible solutions to anisometropia?

Answer 8

Size lenses
CLs
Steps in prescribing to aid adaptation (adults)

Question 9

What are the possible causes of any BV problem?

Answer 9

Refractive error
Anatomical anomalies (e.g. EOM attachment, trauma, abnormal development)
Neuro (not enough or too much EOM innervation)
Health/lifestyle (systemic or ocular disease caused by ‘poor’ choices)

Question 10

What are some ways that BV anomalies can be managed?

Answer 10

Orthoptic exercises
Spherical manipulation (only for pre-presbyopes)
Prism
Referral to orthoptist