FN: Strabismus/Squint/Tropia

Question 1

Esotropia =

Answer 1

Convergent squint

• commonest type in children
• may be idiopathic or due to hypermetropia

Question 2

Exotropia

Answer 2

Divergent squint

• Older children
• Often intermittent

Question 3

Non-paralytic squint diagnosis

Answer 3

Corneal reflection: should fall centrally and symmetrically on each cornea
Cover test: movement of uncovered eye to take up fixation demonstrates manifest squint.

Question 4

Non-paralytic squint Mx

Answer 4

3 O’s

• Optical: correct refractive errors
• Orthoptic: patching good eye encourages use of squinting eye
• Operations e.g. resection and recession of rectus muscles - help alignment and cosmesis

Question 5

Paralytic squint

Answer 5

Diplopia is most on looking in direction of pull of paralysed muscle.
Eye wont fixate on covering
Cover each eye in turn: which ever eye sees the outer image is malfunctioning

Question 6

Paralytic squint CNIII

Answer 6

• Ptosis (LPS)
• Fixed dilated pupil (no parasympathetic)
• Eye looking down and out

Question 7

Paralytic squint CNIII causes

Answer 7

Medical: DM, MSm infarction
Surgical: Raised ICP, cavernous sinus thrombosis, posterior communicating artery aneurysm

Question 8

Paralytic squint CNIV

Answer 8

• Diplopia espcially on going down stairs

- Head tilt

Question 9

Paralytic squint CNIV test

Answer 9

Cant depress in adduction

Question 10

Paralytic squint CNIV causes

Answer 10

Peripheral: DM (30%), trauma (30%), compression
Central: MS, vascular, SOL

Question 11

Paralytic squint CNVI

Answer 11

eye is medially deviated and cannot adduct

Diplopia in the horizontal plane

Question 12

Paralytic squint CNVI causes

Answer 12

peripheral: DM, compression, trauma
Central: MS, vascular, SOL

Question 13

Paralytic squint CNVI Rx

Answer 13

Botulinum toxin can eliminate need for surgery