INTERMITTENT NEAR EXOTROPIA Flashcards
concom
what is an int near xt?
Exotropia at near, BSV in distance (> 10^ difference near to distance)
- True – uniocular occlusion no change
- Simulated – occlusion increases distance angle to = near
Simulated is rare – managed the same as non-specific
int nr xt True : Aetiology:
Coincidental finding on routine assessment
Suggested association with low AC/A ratio (Plenty (1988) found AC/A of 2:1 quite common in normal controls)
Less obvious – possibly why rarely seen in children, Older children and young adults – able to communicate symptoms
Characteristics of int nr xt
XT at near, X in distance with BSV
Asthenopic symptoms (Ocular fatigue, Discomfort, Watering, Headaches)
Diplopia
Equal VA
Poor binocular convergence
NRC
Normal sensory fusion
Reduced positive motor fusion amplitude (BO wont be as good)
Investigation:
on int nr xt
Case history – symptoms
VA
CT
BSV (Bag gls in distance to see if NRC, synoptopher, frisby)
PCT (10 ^ difference)
OM – Normal
NPC – Reduced
AC/A ratio – low?
Differential Diagnosis: of int nr xt
Convergence palsy (No convergence – BO ^ at 1-2m not o/c)
Convergence insufficiency (CT near – XOP not manifest)
Decompensating near X (Normal or large +ve fusional amplitude c dip)
Accommodative convergence insufficiency (Reduced amplitude of accommodation)
Loss of motor fusion (Hx of head trauma and encephalitis or idiopathic. Long Hx of CI, some acute presentation. D PFR reduced, accomm reduced sometimes)
mx for int nr xt (non surgical)
- Correct refractive error – may occur in myopia onset (teenager)
Better response than distance and nonspecific - Orthoptic Exercises (<25∆)
* Recognition of dip
* Fusion of images
* Extension of +ve fusion amplitude & convergence - Prisms
* BI to relieve symptoms
* Just sufficient to allow BSV
* Strength reduced in stages
* +/- orthoptic exercises
* Can incorporate - Botulinum Toxin
* Limited use
* LR injected = ET in distance with dip
