squint classification and direction

Question 1

What is the definition of squint?

Answer 1

A condition where the eyes do not properly align with each other

Squint can be classified into various types based on the nature of deviation.

Question 2

What are the two main classifications of squint?

Answer 2

• Apparent deviation
• True deviation

Apparent deviation includes pseudostrabismus, while true deviation includes heterotropia.

Question 3

What is heterotropia?

Answer 3

Manifest squint that is always visible

It contrasts with latent squint, which manifests under ocular stress.

Question 4

Define comitant squint.

Answer 4

Deviation remains constant in all directions of gaze

The degree of deviation does not change as the eyeball moves.

Question 5

Define incomitant squint.

Answer 5

Deviation varies in different directions of gaze

The degree of deviation changes based on the direction the eye is looking.

Question 6

What is diplopia?

Answer 6

Double vision

It can occur due to misalignment of the eyes.

Question 7

What does head posturing indicate in squint cases?

Answer 7

A compensatory mechanism to align vision

Patients may adopt specific head positions to minimize diplopia.

Question 8

What is Hering’s law?

Answer 8

Equal and simultaneous innervation flows through yoke muscles

This law explains the coordinated movement of both eyes.

Question 9

What is the forced duction test used for?

Answer 9

To assess the mobility of the eye

A negative test indicates the eye moves, while a positive test indicates restriction.

Question 10

What is the difference between paralytic squint and restrictive squint?

Answer 10

• Paralytic squint: Forced duction test is negative
• Restrictive squint: Forced duction test is positive

This distinction helps in diagnosing the underlying cause of the squint.

Question 11

What is the classification of squint that involves outward deviation?

Answer 11

EXO Deviation - Outward

RE Exotropia: Moves out.

Question 12

What is the classification of squint that involves inward deviation?

Answer 12

ESO Deviation - Inward

RE Esotropia: Moves in.

Question 13

What is the classification of squint that involves upward deviation?

Answer 13

HYPER Deviation - Upward

RE Hypertropia: Moves up.

Question 14

What is the classification of squint that involves downward deviation?

Answer 14

HYPO Deviation - Downward

RE Hypotropia: Moves down.

Question 15

What is the classification of squint that involves inward/nasal rotation?

Answer 15

INCYCLO Deviation - Inward/Nasal Rotation

RE Incyclotropia.

Question 16

What is the classification of squint that involves outward/temporal rotation?

Answer 16

EXCYCLO Deviation - Outward/Temporal Rotation

RE Excyclotropia.

Question 17

What are the consequences of squint?

Answer 17

• Seen in image formation
• Motor adaptations
• Sensory adaptations
• Diplopia
• Change in head posture
• Suppression of visual sensory impulse
• Amblyopia

Amblyopia is the loss of vision without an organic cause and has no treatment.

Question 18

What is diplopia in the context of squint?

Answer 18

Images of the same object formed at non-corresponding points in both retinae

This occurs in small angle squint.

Question 19

What is anomalous retinal correspondence (ARC)?

Answer 19

Formation of new correspondence points with deviation up to 5°

Extra work performed by extraocular muscle to overcome small angle deviation.

Question 20

What is the result of large angle squint?

Answer 20

Images of different objects; brain confused trying to fuse two non-related images

Both eyes looking at different objects.

Question 21

What is suppression in the context of squint?

Answer 21

Suppression of visual sensory impulse from the deviated eye

This can lead to amblyopia.