1. Also known as heterotropia
Squint or strabismus
Also known as heterotropia

2. It is an ocular misalignment that results from an imbalance in the extraocular muscles functioning which results in deviation of one or both eye abnormally.

4. Directions
Two types
Phoria – tendency for the eye to turn when disturbances in binocularity
Tropia – condition of full time eye misdirection
Esotropia – turning in
Exotropia – turning out
Hypertropia – turning up
Hypotropia - turning down

6. Etiology Usually associated with childhood
Weak extra ocular muscles – unknown reasons
Adults will have after an injury, brain tumor, head trauma, stroke, retinal detachment repair
An estimated 2% to 3% of the general population have some degree of strabismus

7. Pathophysiology
The six muscles that attach to each eye move the eyes and align them with each other
When these muscles do not work in a co-ordinated fashion due to causes like weakness in muscles or unknown causes
Loss of alignment
strabismus

8. Management Diagnosed by physical examination Cover testing
corneal light reflex (Hirschberg test)

9. Cover test Patient focus on a near object
A cover is placed over an eye for a short period then removed while observing both eyes for movement
Lazy eye will deviate inwards or outwards

10. Management
Glasses with prisms (A prism is a clear, wedge-shaped lens that bends, or refracts, light rays) can realign the eyes and restore binocular vision
Patching the good eye to strengthen the poorer seeing eye is the initial treatment of choice
Eye exercises to strengthen the weak muscles – not proved but still trying

12. Surgical correction is the standard treatment
Surgery conducted as an outpatient procedure
Local or general anesthesia

13. The extra ocular muscles are selectively weakened (recession), tightened (resection), or physically shifted (transposition) to achieve balanced eye movement
Adjustable sutures is used to achieve more accurate alignment

14. Drug therapy Botulinum neurotoxin A (botox)
It can injected into the extraocular muscle and interfere with the release of acetylcholine at the neuromuscular junction
The toxin appears to strengthen the antagonist muscle and weaken the injected muscle