Certified Ophthalmic Assistant Practice Exam

What is the primary function of the ciliary body?

1. Regulate light entry

2. Support the retina

3. Produce aqueous humor

4. Control eye movement

The correct answer is: Produce aqueous humor

The primary function of the ciliary body is to produce aqueous humor, which is the clear fluid found in the anterior chamber of the eye. This fluid plays a crucial role in maintaining intraocular pressure, providing nutrients to the avascular structures of the eye like the lens and cornea, and facilitating the removal of metabolic wastes. The ciliary body also contains the ciliary muscle, which is involved in the process of accommodation—adjusting the lens shape for focusing on near or distant objects. In contrast, the regulation of light entry is primarily managed by the iris, which controls the size of the pupil. Supporting the retina involves the role of structures like the vitreous body and retinal pigment epithelium rather than the ciliary body. Lastly, eye movement is controlled by extraocular muscles, not the ciliary body, which focuses mainly on functions pertaining to the lens and aqueous humor production.