Classification Of Heterophoriaa And HeteroTropia

Question 1

What is a convergence excess esophoria

Answer 1

• deviation 10 degrees greater at near fixation

Question 2

What is a divergence weakness esophoria

Answer 2

• deviation 10 degrees greater at distance fixation

Question 3

What is a convergence weakness exophoria

Answer 3

• deviation 10 degrees greater at near

Question 4

What is a divergence excess exophoria

Answer 4

• deviation 10 degrees greater at distance

Question 5

In vertical phorias, which eye is the nomenclature of the deviation determined by

Answer 5

• high or elevated eye

Question 6

What is an exyclophoria

Answer 6

• upper poles of the corneas deviate outwards when fusion is prevented

Question 7

What is incyclophoria

Answer 7

• upper poles of the corneas deviate inwards when fusion is prevented

Question 8

What is a concomitant heterophoria

Answer 8

• dissociated deviation remains the same whichever is is used to fixate
• no significant change in 9 positions of gaze

Question 9

What is an Incomitant strabismus

Answer 9

• dissociated deviation increases when one eye is made to fixate and decreases when the other eye fixates
• increases/decreases in some positions of gaze

Question 10

Aetiology of incomitant heterophoria

Answer 10

• most seen in presence of paralytical or mechanical strabismus
• diagnosed according to the underlying cause
• hyper/hypo/cyclophorias are almost always Incomitant

Question 11

What causes incomitance

Answer 11

• underaction of one or more EOMs, due to cranial nerve palsy or mechanical factors
• uncorrected spherical anisometropia

Question 12

Characteristics of incomitant heterophorias

Answer 12

• increases when paretic eye is made to fixate
• decreases when fellow eye fixes
• varies when dissociated in different positions of gaze

Question 13

What is a concomitant heterotropia

Answer 13

• ocular ovement is within normal limits at time of onset of strabismus
• angle of deviation is virtually the same whichever eye is used for fixation in the primary position

Question 14

What is an Incomitant heterotropia

Answer 14

• occurs when there is a limitation of ocular movement
• the angle of deviation increases as the eyes are turned in the direction of limitation and decreases when turned in the opposite direction with the exception of echanical palsies

Question 15

3 types of esotropia

Answer 15

• primary
• secondary
• consecutive

Question 16

What is a primary esotropia

Answer 16

• the convergent deviation constitutes the initial defect
• esotropia present under all conditions
• with accommodative element = deviation increases when accommodation is exerted
• without an accommodative = deviation is unaffected by state of accommodation

Question 17

Characteristics of infantile esotropia

Answer 17

• onset before 6 months
• large, up to 45 degrees
• constant angle of deviation
• usually alternating
• not accommodative
• associated with dissociated vertical divergence and latent nystagmus that develops 12-18 months

Question 18

Primary intermittent esotropia

Answer 18

• only present under certain conditions
• px have normal retinal correspondence

Question 19

What is accommodative esotropia

Answer 19

• In accommodative squint, the state of convergent deviation is affected by the state of accommodation
• primary factor in the aetiology

Question 20

What is a cyclic esotropia

Answer 20

• every 24/48 hours
• deviation occurs at regular intervals
• will become constant

Question 21

What is a secondary esotropia

Answer 21

• esotropia which occurs after pathological loss or impairment of vision

Question 22

What is a consecutive esotropia

Answer 22

• esotropia in a patient who as previously had exotropia or exophoria

Question 23

3 types of exotropia

Answer 23

• primary
• secondary
• consecutive

Question 24

What is a primary exotropia

Answer 24

Divergent deviation constitutes the initial defect

Question 25

Constant exotropia

Answer 25

- exotropia is present under all conditions - early onset - rare - suspect low VA

Question 26

What is a distance exotropia

Answer 26

- exotropia on distance fixation - binocular vision on near fixation - angle of deviation might increase on prolonged distraction of occlusion or elimination of accommodation

Question 27

What is a non specific exotropia

Answer 27

- exotropia which shows intermittent binocular vision not conforming to any pattern

Question 28

What is a secondary exotropia

Answer 28

- exotropia which occurs after pathological loss or impairment of vision

Question 29

What is a consecutive exotropia

Answer 29

- exotropia in a patient who has previously had esotropia or esophoria - other spontaneous or post operative

Question 30

What is pathological binocular diplopia

Answer 30

- initially the px appreciates diplopia - this results from the simultaneous appreciation of two separate images caused by the stimulation of non corresponding points by the Same object - the diplopia at be horizontal, vertical or torsional

Question 31

What is Homonymous pathological diplopia

Answer 31

- uncrossed - binocular diplopia associated with esotropia - image is received on the nasal retina of the deviating eye and is therefore projected temporally it results when non-corresponding retinal points are stimulated by the same object

Question 32

What is hetronymous pathological diplopia

Answer 32

- Crossed - binocular diplopia associated with exotropia - image on temporal retina

Question 33

What is suppression

Answer 33

- cortical mechanism - occurs when there is confusion - squints in Older px, diplopia is symptomatic - abnormal retinal correspondence describes a condition which in non NRC areas of both eyes co-operate to produce a form of binocular single vision