OCANZ Exam Study Guide Questions And Answers
Verified 100% Correct
What is n for nominal index on lens measure? - ANSWER 1.53
What are the different plate designs in an Ishihara test? - ANSWER Demonstration,
Transformation, Vanishing, Hidden, Diagnostic
What can the D15 test be used for? - ANSWER Classifying type of a defect
What is the purpose of 100 hue test? - ANSWER Classifying type and severity
What is Sheard's criterion? - ANSWER Fusional reserve must be at least 2 x demand.
Prism needed = 2/3(phoria) - 1/3(BO to blur)
What is the 1:1 Rule? - ANSWER Base in recovery should be at least equal to the
amount of esophoria, base out prism needed = (esophoria - BI recovery)/2
What is Percival's rule? - ANSWER Comfort zone is in the middle third of the width of
clear single vision, prism needed = 1/3(Greater of lateral range blur limit BI or BO) -
2/3(less of lateral range blur limit)
When will patients adopt a face turn? - ANSWER Horizontal deviation
In a left lateral rectus palsy what head turn would be expected and why? - ANSWER
Head will be turned to the left which deviates the eyes to the right away from muscle
weakness
When will a px adopt an elevation or depression? - ANSWER In A or V patterns
What is a base out prism test? - ANSWER 20 base out prism in front of one eye, other
eye should shift to take up fixation then first eye take up compensatory movement.
Which intermittent esotropias require surgery? - ANSWER Near, distance, cyclic, non
specific
How would you manage a constant esotropia with an accommodative element? -
ANSWER Order full rx, treat amblyopia, surgery if cosmetically poor
What is a consecutive esotropia? - ANSWER Eso in a px who initially had an exo as a
,result of surgical over correction often intentional
What are the types of esophoria? - ANSWER Convergence excess, divergence
weakness, non-specific
What are the types of exophoria? - ANSWER Convergence weakness, divergence
excess, non-specific
List 5 ways accommodation can be defective. - ANSWER 1 - Presbyopia, 2 -
Accommodative insufficiency, 3 - accommodative fatigue, 4 - accommodative inertia, 5 -
accommodative paralysis
What is the normal range of AC/A ratio? - ANSWER 3 - 5
What can cause a limitation of movement? - ANSWER 1) neurogenic, 2) mechanical 3)
myogenic
What muscles cause an A eso? - ANSWER LR and IO
What muscles cause an A exo? - ANSWER IR and MR
What causes V eso? - ANSWER SO
What causes V exo? - ANSWER SR
What muscles are affected by a IIIrd nerve palsy? - ANSWER Medial, inderior and
superior recti, inferior oblique, sphincter pupillae, ciliary muscle, levator
What muscle is affected by a IVth nerve palsy? - ANSWER Superior oblique
What muscle is affected by a VIth nerve palsy? - ANSWER Lateral Recturs
What is the most common congenital muscle palsy? - ANSWER 4th nerve
What will be the appearance of a 4th palsy? - ANSWER Eye hypertropic and esotropic
What is the hallmark of a convergence excess esophoria? - ANSWER Greater at near
than distance
What is the hallmark of divergence weakness esophoria? - ANSWER Greater at
distance than near
What is the hallmark of a convergence weakeness exo? - ANSWER Greater at near
with convergence insufficiency
, What is the hallmark of divergence excess exo? - ANSWER Greater at distance than
near
What are typical fusional reserves for base out near fixation? - ANSWER 30-35D
What are typical fusional reserves for base in near fixation? - ANSWER 12-14D
What are typical fusional reserves for base out distance fixation? - ANSWER 20-25D
What are typical fusional reserves for base in distance fixation? - ANSWER 6-8D
What are typical fusional reserves for vertical base? - ANSWER 2-4D
How do you perform fusional reserves? - ANSWER Introduce prism gradually, record
blur / break / recovery
What are exercises to improve esophoria and what is the aim? - ANSWER Aim to
improve negative relative convergence - stereograms, bar reading and fusional reserve
exercises
What are the exercises to improve exophoria and what is the aim? - ANSWER Aim to
improce positive relative convergence with stereograms, fusional exercises
What causes a high AC/A ratio? - ANSWER Accommodative esotropia
What causes a low AC/A ration? - ANSWER More exotropic at near
What is the relationship between Ks and corneal astigmatism? - ANSWER 0.1mm =
0.50 astigmatism
What can be done to amend an RGP with high decentration? - ANSWER Reduce lens
thickness, reduce total diameter, may have excessive amounts WTR astigmatism -
back surface toric
How can lens movement be increased? - ANSWER Increase BOZR, Decrease BOZD,
Decrease TD
A px presents with irritated lens, mucus and excessive lens movements as well as lens
deposits, investigation shows papillae and follicles on both upper lids and superior
corneal staining. What is the cause and management? - ANSWER CLIPC - Cease lens
wear, change lens material to lower modulus and more frequent replacement plan, cold
compress, reduce WT, improve hygiene, sodium cromglycate
Verified 100% Correct
What is n for nominal index on lens measure? - ANSWER 1.53
What are the different plate designs in an Ishihara test? - ANSWER Demonstration,
Transformation, Vanishing, Hidden, Diagnostic
What can the D15 test be used for? - ANSWER Classifying type of a defect
What is the purpose of 100 hue test? - ANSWER Classifying type and severity
What is Sheard's criterion? - ANSWER Fusional reserve must be at least 2 x demand.
Prism needed = 2/3(phoria) - 1/3(BO to blur)
What is the 1:1 Rule? - ANSWER Base in recovery should be at least equal to the
amount of esophoria, base out prism needed = (esophoria - BI recovery)/2
What is Percival's rule? - ANSWER Comfort zone is in the middle third of the width of
clear single vision, prism needed = 1/3(Greater of lateral range blur limit BI or BO) -
2/3(less of lateral range blur limit)
When will patients adopt a face turn? - ANSWER Horizontal deviation
In a left lateral rectus palsy what head turn would be expected and why? - ANSWER
Head will be turned to the left which deviates the eyes to the right away from muscle
weakness
When will a px adopt an elevation or depression? - ANSWER In A or V patterns
What is a base out prism test? - ANSWER 20 base out prism in front of one eye, other
eye should shift to take up fixation then first eye take up compensatory movement.
Which intermittent esotropias require surgery? - ANSWER Near, distance, cyclic, non
specific
How would you manage a constant esotropia with an accommodative element? -
ANSWER Order full rx, treat amblyopia, surgery if cosmetically poor
What is a consecutive esotropia? - ANSWER Eso in a px who initially had an exo as a
,result of surgical over correction often intentional
What are the types of esophoria? - ANSWER Convergence excess, divergence
weakness, non-specific
What are the types of exophoria? - ANSWER Convergence weakness, divergence
excess, non-specific
List 5 ways accommodation can be defective. - ANSWER 1 - Presbyopia, 2 -
Accommodative insufficiency, 3 - accommodative fatigue, 4 - accommodative inertia, 5 -
accommodative paralysis
What is the normal range of AC/A ratio? - ANSWER 3 - 5
What can cause a limitation of movement? - ANSWER 1) neurogenic, 2) mechanical 3)
myogenic
What muscles cause an A eso? - ANSWER LR and IO
What muscles cause an A exo? - ANSWER IR and MR
What causes V eso? - ANSWER SO
What causes V exo? - ANSWER SR
What muscles are affected by a IIIrd nerve palsy? - ANSWER Medial, inderior and
superior recti, inferior oblique, sphincter pupillae, ciliary muscle, levator
What muscle is affected by a IVth nerve palsy? - ANSWER Superior oblique
What muscle is affected by a VIth nerve palsy? - ANSWER Lateral Recturs
What is the most common congenital muscle palsy? - ANSWER 4th nerve
What will be the appearance of a 4th palsy? - ANSWER Eye hypertropic and esotropic
What is the hallmark of a convergence excess esophoria? - ANSWER Greater at near
than distance
What is the hallmark of divergence weakness esophoria? - ANSWER Greater at
distance than near
What is the hallmark of a convergence weakeness exo? - ANSWER Greater at near
with convergence insufficiency
, What is the hallmark of divergence excess exo? - ANSWER Greater at distance than
near
What are typical fusional reserves for base out near fixation? - ANSWER 30-35D
What are typical fusional reserves for base in near fixation? - ANSWER 12-14D
What are typical fusional reserves for base out distance fixation? - ANSWER 20-25D
What are typical fusional reserves for base in distance fixation? - ANSWER 6-8D
What are typical fusional reserves for vertical base? - ANSWER 2-4D
How do you perform fusional reserves? - ANSWER Introduce prism gradually, record
blur / break / recovery
What are exercises to improve esophoria and what is the aim? - ANSWER Aim to
improve negative relative convergence - stereograms, bar reading and fusional reserve
exercises
What are the exercises to improve exophoria and what is the aim? - ANSWER Aim to
improce positive relative convergence with stereograms, fusional exercises
What causes a high AC/A ratio? - ANSWER Accommodative esotropia
What causes a low AC/A ration? - ANSWER More exotropic at near
What is the relationship between Ks and corneal astigmatism? - ANSWER 0.1mm =
0.50 astigmatism
What can be done to amend an RGP with high decentration? - ANSWER Reduce lens
thickness, reduce total diameter, may have excessive amounts WTR astigmatism -
back surface toric
How can lens movement be increased? - ANSWER Increase BOZR, Decrease BOZD,
Decrease TD
A px presents with irritated lens, mucus and excessive lens movements as well as lens
deposits, investigation shows papillae and follicles on both upper lids and superior
corneal staining. What is the cause and management? - ANSWER CLIPC - Cease lens
wear, change lens material to lower modulus and more frequent replacement plan, cold
compress, reduce WT, improve hygiene, sodium cromglycate
