Convergence Reflex Test

What is convergence of the lens?

One of three mechanisms for focusing light on the retina when viewing objects closer than 20 feet. The other two are accommodation of the lens and pupil constriction.

What is the fovea centralis?

The most sensitive and acute area of the retina where both eyes focus light to produce sharp images for the brain.

How many extrinsic (extraocular) muscles control eye movement?

Six muscles.

Which cranial nerve innervates the superior oblique muscle?

Trochlear nerve (CN IV) — "SO-4" (Superior Oblique by CN IV).

Which cranial nerve innervates the lateral rectus muscle?

Abducens nerve (CN VI) — "LR-6" (Lateral Rectus by CN VI).

Which cranial nerve innervates the medial rectus, inferior rectus, superior rectus, and inferior oblique muscles?

Oculomotor nerve (CN III) — "AR-3" (All the Rest by CN III).

What muscles does CN III (oculomotor nerve) innervate and their actions?

• Superior rectus: moves eye superiorly and medially

• Inferior rectus: moves eye inferiorly and medially

• Medial rectus: moves eye medially

• Inferior oblique: moves eye superiorly and laterally

What muscle does CN VI (abducens nerve) innervate and its action?

Lateral rectus — moves eye laterally.

What muscle does CN IV (trochlear nerve) innervate and its action?

Superior oblique — moves eye inferiorly and laterally.

What is the purpose of the convergence reflex test?

To assess the coordinated movement of the two eyes tracking a close object and to evaluate the function of CN III, IV, and VI.

Define convergence in terms of eye movement.

Both eyes turning inward to focus on a close object.