Hesi A2 Anatomy section: the eye

What are the three layers of the eye?

• Outer fibrous layer

• Middle vascular layer

• Inner neural layer

What makes up the outer fibrous layer?

• Sclera

• Cornea

What does the sclera do?

• Sclera: The "white of the eye" that provides protection and maintains shape.

What does the cornea do?

• Cornea: The transparent front part that allows light to enter and helps refract (bend) it.

What makes up the middle vascular layer?

• Choroid

• Ciliary Body

• Iris

What does the choroid do?

• Choroid: Contains blood vessels that supply oxygen and nutrients to the retina.

What does the ciliary body do?

• Ciliary Body: Produces aqueous humor and controls the shape of the lens for focusing (accommodation).

What is aqueous humor?

It is a clear, watery fluid that fills the front part of the eye, specifically the space between the cornea and the lens. It is composed of approximately 99.9% water, with the remaining 0.1% consisting of essential nutrients like sugars, vitamins, and proteins.

What does the Iris do?

• Iris: The pigmented (colored) part that uses smooth muscle to regulate pupil size and light intake.

What is the pathway for light and vision in the eye?

Cornea, Aqueous Humor, Pupil, Lens, Vitreous Humor, Retina

How does the brain receive visual information?

The Retina sends impulses through the Optic Nerve to the Visual Cortex in the Occipital Lobe of the brain for interpretationC

Common eye disorders

• Myopia (Nearsightedness): Objects far away are blurry; light focuses in front of the retina.

• Hyperopia (Farsightedness): Objects nearby are blurry; light focuses behind the retina.

• Presbyopia: Age-related loss of lens elasticity, making it hard to focus on close objects.

• Cataracts: Clouding or opacity of the lens, often due to protein clumping.

• Glaucoma: Increased intraocular pressure that can damage the optic nerve, often leading to loss of peripheral vision

What is the purpose of aqueous humor?

• Waste removal

• Nourishment

• Intraocular pressure

• Light refraction

What is the retina's role in vision?\n\n

• Retina: It converts light into neural signals and sends them to the brain for visual interpretation.

What is the function of the optic nerve?\n\n

• Optic Nerve: Transmits visual information from the retina to the brain.

What types of cells are found in the retina?\n\n

• Rods: Responsible for vision in low light conditions.\n\n- Cones: Responsible for color vision and detail in bright light.

What is the vitreous humor?\n\n

• Vitreous Humor: A gel-like substance that fills the space between the lens and the retina, helping maintain eye shape.

What is the significance of the scleral venous sinus?\n\n

• Scleral Venous Sinus (Canal of Schlemm): It drains aqueous humor from the eye, regulating intraocular pressure.