Strabismus

Question 1

What is the peak onset for strabismus?

Answer 1

3 (most prior to age 6)

Question 2

What are some major risk factors for strabismus?

Answer 2

Craniofacial dysotosis 90%
Down syndrome 50%
Cerebral palsy 44%
Family hx

Question 3

Strabismus hx

Answer 3

• onset (time, sudden or gradual?)
• frequency (constant or intermittent?)
• change in size or frequency
• unilateral or alternating
• diplopia or other symptoms
• head tilt/turn
• hx of neuro/systemic/dev disorders***
• family hx*
• previous tx

Question 4

S/S of strabismus

Answer 4

• abnormal motility of one or both eyes
• double vision
• decr vision and stereo
• ocular discomfort (fatigue)
• HA
• abnormal head posture
• blurred vision
• cosmetic (low self esteem)

Question 5

Tests you must to do identify strabismus (when eyes are not properly aligned with each other)

Answer 5

• CT 9 fields
• W4D
• DFE

Consider: visuoscopy, anomalous correspondence (what are thoseee???)

Classifications: dist/near
Magnitude: PD
Direction: ET, XT, hypertropia, cyclotorsion
Comitance
Frequency: constant/intermittent (%)
Laterality: alternating (% OD vs OS), unilateral

Question 6

What is comitant strabismus?

Answer 6

Magnitude is equal in all directions of gaze (within 5PD)

• decompensating phoria
• congenital strabismus

Question 7

Noncomitant strabismus

Answer 7

• usually muscle/nerve problem (acquired)
• deviation largest in direction of action of affected muscle/nerve
• deviation varies w/ eye used for fixation
• document in 9 fields

Question 8

Types of strabismic ET

Answer 8

• pseudo ET
• infantile ET
• acquired ET (acc/nonacc, acute)
• secondary ET (sensory/consecutive)
• micro ET

Question 9

Types of strabismic XT

Answer 9

• infantile
• acquired (intermittent/acute)
• secondary
• micro XT

Question 10

What is pseudo ET

Answer 10

• CT and Hirschberg normal
• Cause:
  — flat, broad nasal bridge, prominent epicanthal folds, narrow IPD

Eyes usually straighten by ~2-3 months

Question 11

When does ET usually present itself?

Answer 11

Most present before school age — often CONSTANT

Question 12

What is basic ET?

Answer 12

When ET is within 10PD at dist AND near

Question 13

What is CE ET?

Answer 13

Near > dist by 10PD

Question 14

What is DI ET?

Answer 14

Dist > near by 10PD

Question 15

What is infantile esotropia?

Answer 15

8.1% of ET

Confirmed onset earlier than 6 months

AMBLYOPIA IN 40-72%

Cross fixation

• OD views left field and vv
• EOMs may show abduction deficit (this is a cross fixation, not a true deficit; monocular ductions: MR can become tight if unilateral)

Normal RE

40-60PD range, D=N

Question 16

What are some associated findings w/ infantile ET?

Answer 16

DVD: slow upward movement of one/both eyes when covered; may show hyper deviation of each eye when covered — NO HYPO DEVIATION

IO over action 78%
Nystagmus 30%
Poor N->T OKN response

Question 17

Infantile ET treatment

Answer 17

Specs
BNO
Patching
VT
Prism
Sx

Question 18

What is accommodative ET?

Answer 18

50% childhood ET are fully or partially accommodative

Hyperopia (~2.00D to 6.00D)
- ANISOMETROPIA increases risk

Deviation N>D, 10-35PD

Normal to high AC/A

Question 19

Treatment for accom ET

Answer 19

Optical correction
Near add
VT

Question 20

What is nonrefractive accom ET?

Answer 20

5% of accom ET pts

Minimal RE

ET at near — STRICTLY d/t NEAR ACCOM

High AC/A

Question 21

Treatment for nonrefractive accom ET

Answer 21

Specs
Near Add — Plus lenses improve alignment
VT

Question 22

A bifocal must be prescribed to help accom ET pts see at near. True or false?

Answer 22

True — should bisect the pupil

Question 23

What is non-accom ET?

Answer 23

Onset 6mo-6yrs
~10% of all ET
Most hyperopic; 5% myopic
20-70PD range
Normal AC/A