Anatomy of the Eye PPT SB

Home , Ciliary body, Cornea, Iris (anatomy), Pupil, Vitreous body

Anatomy of the Eye Introduction

By the end of this module, you will be able to: • Describe the anatomical structures of the eye. • Identify the layers of the eye. • Describe the contents of the eye. • Describe the structures associated with the eye.

Eyebrow Short hairs rooted in the skin just over the upper margins of the eye’s orbital cavity. Eyelid The eyelids cover, protect, and lubricate the eyeball. Eyelash Short hairs bordering the delicate eye structure. Like cilia in other parts of the body, the eyelashes trap foreign particles.

© ALCON. Confidential. ALCON training purposes only. Do not distribute. 4 Interior View of the Eye Retina (example) here… Definition text for each element in the interior view will appear when rolled over.

Focal Point (example) here…

© Alcon. Confidential. ALCON training purposes only. Do not distribute. 5 1. Light is reflected from the object and passes in the How Do We See? eye through the cornea. 2. The iris regulates the size of the pupil, the opening that controls the amount of light that enters the eye.

3. Behind the pupil is the lens, which further focuses light, or an image, onto the retina.

4. The retina is a thin, delicate, photosensitive tissue that contains the special “photoreceptor” cells that convert light into electrical signals.

5. These electrical signals are processed further, and then travel from the retina of the eye to the brain through the optic nerve.

6. We “see” with our brains; our eyes collect visual information and begin this complex process.

Medial and Lateral Toward the center line of the body. For example, nose is medial to each eye, and farther away from the center of the body.

Nasal and Temporal Refers to the nose and can be substituted for medial, and temporal refers to the temple area on either side of the head.

Superior and Inferior Refers to a structure above another and a structure below another.

Posterior and Anterior Toward the rear of the head and toward the front of the head.

Anterior Segment Cornea, Iris, ciliary body, crystalline lens

Chambers of the Anterior Segment The anterior chamber, and posterior chamber.

Posterior Segment Eye’s largest cavity, and includes the retina and optic disc.

© Alcon. Confidential. ALCON training purposes only. Do not distribute. 9 SHOW WHAT YOU KNOW Click on an anatomical part of the eye and drag it to its proper location. Click the Check Answer button when you are finished.

Brow Retina

Lashes Sclera

Iris Pupil

Corneal-Scleral- Conjunctiva Limbus Check Answer

10 SHOW WHAT YOU KNOW Choose the correct letter for each anatomical part of the eye. Click the Check Answer button when you are finished.

A. Cornea

B. Crystalline Lens

C. Retina

D. Optic Nerve Fibers

Check Answer

11 SHOW WHAT YOU KNOW Match each part of the eye to its description. Click the Check Answer button when you are finished.

Eyelid A. [Eyelid] They cover, protect, and lubricate the eyeball. B. [Eyelash] Short hairs bordering the delicate eye structure. Like cilia in other parts of the body, the eyelashes trap foreign particles. Eyelash C. [Cornea] The cornea is anterior to both the lens and retina. Cornea is the clear front window of the eye that transmits and focuses light into Cornea the eye. D. [Pupil] The iris regulates light that enters the eye through the pupil, Pupil the hole in the center of the eye. E. [Iris] The iris is the colored or pigmented tissue of the eye just behind Iris the cornea and in front of the lens. The muscles of the iris contract and expand to change the size of the pupil in different lighting Check Answer conditions.

12 Anatomy of the Eye Segment 3: Layers of the Eye

The fibrous layer is the outermost layer that protects and supports the shape of the globe to avoid optical distortion.

The vascular layer is the middle layer; also known as the uvea. It supplies blood to the globe. It is an important source of oxygen and nutrients for the globe.

The nervous layer is the inner layer, also known as the retina. It transmits sensory information about light to the brain.

• Sclera

• Limbus

• Cornea

Choroid

Structure The choroid lies between the retina and sclera. It is composed of layers of blood vessels that nourish the outer retina.

Functions The choroid supplies nutrients to the outer retina and helps regulate the ocular temperature.

Retina

Structure The nervous layer or the retina is a complex tissue that makes up the internal two-thirds of the back of the eye. It contains nerve fibers that are long cell extensions through which sensory information travels.

Functions The retina, which is the innermost layer of the eye, performs the function that gives the eye its purpose—it detects light and sends sensory information to the brain for processing.

• Pupil

• Iris

• Ciliary Body

• Choroid

Structure The iris is the colored or pigmented tissue of the eye just behind the cornea and in front of the lens. The muscles of the iris contract and expand to change the size of the pupil in different lighting conditions.

Function The iris regulates light that enters the eye by modifying the size of the pupil, the hole in the center, and through constriction or dilation.

Ciliary Muscles The ciliary muscles alter the shape of the lens to adjust and focus vision in a process called accommodation.

Zonular Fibers The zonular fibers suspend the lens from the ciliary muscles.

Ciliary Processes The ciliary processes are finger-like projections from the ciliary muscles that produce aqueous humor.

There are 10 unique layers of the retina.

They receive light from an object and convert it into electrical impulses that are then transmitted to the brain.

Ophthalmoscope

Gives eye-care professional an idea about the state of the tissues in the back of the eye, such as the retina, choroid, and major blood vessels.

The Fundis includes:

• Macula lutea

• Fovea centralis

• Optic disc

The eye’s anterior and posterior segments are filled with fluids, or humor.

This plays a vital role in maintaining ocular function.

These fluids are called the aqueous humor and vitreous humor.

Aqueous Humor Vitreous Humor Production. Fills the anterior segment of the eye. The vitreous, made up of the vitreous body and the Thin, clear, and watery fluid produced by the vitreous cortex, fills the large cavity between the lens epithelial tips of the ciliary body, located in the and the front of the retina. posterior chamber. It is mostly water (roughly 98% to 99%) and Drainage. Flows from the posterior chamber, through macromolecules. the pupil, into the anterior chamber, and then drains out through the angle that balances the production The cortex, or outer portion, is easily distinguishable and drainage to maintain intraocular pressure. from the body because it has a high concentration of matrix proteins. Function. Aqueous humor supplies nutrients for the lens and cornea and carries away waste and carbon dioxide.

Structure The crystalline lens is a transparent, flexible structure located in the anterior portion of the eye, behind the iris.

Most of the lens is made up of lens fibers that are packed into tight, onion-like layers that contains no blood vessels.

Gets nutrition from the fluids that surround it, primarily the aqueous.

External portion, or cortex, has a higher rate of metabolism than its internal portion, or nucleus.

Function The lens changes shape to focus light rays on the retina, which enables the eye to see objects at a range of distances.

© Alcon. Confidential. ALCON training purposes only. Do not distribute. 30 SHOW WHAT YOU KNOW When referring to the aqueous and vitreous parts of the eye, select A for aqueous or V for vitreous to the following questions.

[V] Composed mostly of water, it fills the large cavity between the lens and the front of the retina.

[A] Thin, clear, and watery, it fills the anterior segment of the eye.

[A] Flows from the posterior chamber, through the pupil, into the anterior chamber, and then drains out through the angle.

[A] Supplies nutrients for the lens and cornea.

31 SHOW WHAT YOU KNOW Which of the following statements is correct?

A. Light is refracted as it passes through the cornea and crystalline lens before it reaches the retina.

B. When the eye views an object at all distances, the ciliary muscle relaxes.

C. The nervous layer, or retina, consists of five separate layers.

D. The cornea acts like an aperture on a camera, regulating light that enters the eye.

32 SHOW WHAT YOU KNOW

Extraocular muscles are a collection of six muscles that control the movements of the eyeball and are named for positions to the globe. qTrue qFalse

33 SHOW WHAT YOU KNOW The eye is a nearly spherical organ that contains three concentric layers. Match the three concentric layers to their correct description. Composed of two structures, the sclera and the cornea. Fibrous layer Made up of three segments – the iris, the ciliary body, Vascular layer and the choroid.

Nervous layer Referred to as the retina, it consists of 10 unique layers that transmits sensory information about light to the brain.

34 SHOW WHAT YOU KNOW Fill in the blank. The conjunctiva is a thin, transparent, mucous membrane that lines the eyelids and sclera, but not the _[cornea]__.

35 CONGRATULATIONS!

You have successfully completed the Anatomy of the Eye module.

You should be able to: • Describe the anatomical structures of the eye. • Identify the layers of the eye. • Describe the contents of the eye. • Describe the structures associated with the eye.