Binocular Vision & Strabismus Flashcards

In a patient with exotropia, the deviating eye turns in which direction?

Answer: Outward (temporal)

Exotropia is an outward (temporal/lateral) deviation of the eye, often called 'wall-eye.'

The Maddox rod test is primarily used to assess:

Answer: The magnitude and direction of a phoria

The Maddox rod converts a point light source into a streak, completely dissociating the eyes so that any phoria can be measured with neutralizing prisms.

Anisometropic amblyopia develops primarily because:

Answer: A significant refractive difference between the two eyes causes chronic blur in one eye

A large interocular refractive difference results in one eye receiving a chronically defocused image, leading to cortical suppression and amblyopia despite proper alignment.

Clinically normal stereoacuity is typically defined as a threshold of:

Answer: 40 arc seconds or better

A stereoacuity of 40 arc seconds or better (on tests such as the Randot or Titmus) is considered within normal limits for bifoveal stereopsis.

The Worth 4-Dot test uses red and green filters to evaluate:

Answer: Suppression and the quality of binocular fusion

By presenting red dots only to one eye and green dots only to the other, the Worth 4-Dot test reveals whether the patient is fusing, suppressing one eye, or experiencing diplopia.

Strabismic amblyopia results from which specific cause?

Answer: Constant unilateral strabismus causing chronic suppression of the deviating eye

Constant unilateral strabismus leads to persistent cortical suppression of the deviating eye's fovea, causing amblyopia due to lack of normal visual stimulation.

Convergence insufficiency is most characteristically defined by:

Answer: Exophoria or exotropia that is greater at near than at distance

Convergence insufficiency is characterized by an exodeviation (often exophoria) that is significantly larger at near than at distance, reflecting reduced fusional convergence.