Competency 8.1.1

Question 1

Binocular Status Case History in an Adult Patient

Answer 1

Useful to cover the following:
- History of any trauma
- Medication list (past if relevant)
o Some anti-convulsants can be a cause of reduced ocular motility
- Any past or present systemic conditions which can result in BV issues (think BV and MS)
- Social factors impacting on health
o Alcohol consumption and smoking have been shown to be relevant in cases of reduced motility
- Any BV symptoms (use LOFTSEA if ‘Yes’)
o Headaches
o Dipl
o Asthenopia
o Motion sickness
o Head tilts

Question 2

Binocular Status Case History in Children

Answer 2

Useful to cover the following:
- History of trauma
- Details of any illness and its treatment/effects
- Any general health conditions that have been diagnosed (think congenital syndromes)
- Details of General Development
- Mothers health during pregnancy
- Birth weight
- Full term or premature
- Neonatal issues
o Resuscitaition or intensive therapy
- Family History
o Refractive error
o Strabismus
o VF defects/issues
- Social History
o Is baby in care or with parents
o History of substance abuse?

Question 3

Baby Development Milestones

Answer 3

o 2 months
- Make ‘cooing’ sounds
- Cries when wet, hungry, tired
- Eye contact is maintained
o 9 months
- Sits without support
- Recognises family members
o 24 months
- Can run
- Can name well-known objects
- Can put upto 3 words together

Question 4

Normal Birth Weight

Answer 4

5 lbs 8 oz upto 8 lbs 13 oz is normal

Question 5

How Long is a Normal Pregnancy?

Answer 5

Full term is 37 and 41 weeks

Question 6

Three Parts of a Mallet Unit

Answer 6

• Red (or grey) monocular strips for distance
• Green strips monocular strips for near
• Has a central fixation lock (OXO)

Question 7

What is the Reasoning for the Colouring of Strips on the Mallet Unit

Answer 7

green strips are used at near due to the green strips being more sharply in focus at near which is caused by a slight lag in accommodation.

Question 8

What is a Fixation Disparity?

Answer 8

• refers to the circumstance where BSV is obtained without the object of focus landing perfectly on the fovea of each eye
• can be achieved provided that the misalignment is sufficiently small to allow for the images to still fall into Panum’s fusional area
• Fixation disparity is usually measured with full correction in place

Question 9

Theory Regarding Fixation Disparity

Answer 9

• has been suggested that fixation disparity could indicate that the binocular vision system is under stress
• can be thought of as the part of a phoria which is decompensating
• sometimes the direction of the fixation disparity is not in agreement with the direction of the phoria, this would support the notion that fixation disparity is a physiological phenomenon

Question 10

Interpretation of Fixation Disparity

Answer 10

• vast majority of patients will not suppress and will not require any prism to correct the deviation
• important to note that the size of the fixation disparity is not necessarily indicative of how much prism is required to correct the issue.

Question 11

Prescribing from Fixation Disparity

Answer 11

• prescribe the lowest amount of prism that corrects the issue
• best to see if leaving the prism in place for a few minutes results in the deviation reappearing, . If the patient is ‘swallowing’ prism then prescribing this prism may not be of benefi

Question 12

What is a Maddox Rod Lens?

Answer 12

• red part of trial lens set which is composed of a series of plano-convex cylinders
• turn a spotlight target into a red line with direction at 90 degrees to the orientation of the Maddox rod itself

Question 13

How to Use a Maddox Rod

Answer 13

• The Maddox rod is usually placed in front of the RE resulting in two different images being seen by each eye
• they therefore default to their heterophoric position
• The location of the line in relation to the spotlight target allows for measurement of the size of the phoria

Question 14

Why are Subjective Measures of Phoria Important?

Answer 14

• an objective measure, such as alternate cover test, is insensitive to small deviations smaller than 3^ in size.

Question 15

Maddox Rod Advantages

Answer 15

• Quick
• Easy to perform
• Easy for patient to understand

Question 16

Maddox Rod Disadvantages

Answer 16

• Spotlight represents poor stimulus for accommodation so in theory is only useful for measuring vertical phorias (which are unaffected by accommodation) or in older patients with no remaining accommodation.
• More accurate with trial frame than phoropter as this prevents habitual head tilt