Deck 11: Eyes

Question 1

Identify the external anatomical features of the eye.

Answer 1

Each eye is protected by the bony orbital cavity and is surrounded with a cushion of fat. The eyelids, like two movable shades, further protect the eye from injury, strong light, and dust. The upper eyelid is larger and more mobile. Eyelashes curve outward from the lid margin to filter out dust and dirt. When closed, the lid margins approximate completely. The limbus is the border between the cornea and sclera. The canthus is the corner of the eye, the angle where the lids meet. The caruncle is a small fleshy mass containing sebaceous glands and is located at the inner canthus. A stripe of connective tissue, the tarsal plate, gives shape to the upper lid. Within the tarsal plates are the meibomian glands, modified sebaceous glands that secrete an oily lubrication material onto the lids. The conjunctiva, a thin mucous membrane, is a transparent protective covering of the exposed part of the eye. Constant irrigation is provided by the lacrimal apparatus. Tears drain into the puncta, located on the upper and lower lids at the inner canthus. Six muscles attach the eyeball to its orbit: the superior, inferior, lateral, and medial rectus muscles and the superior and inferior oblique muscles. These muscles serve to direct movement of the eye and are stimulated by cranial nerves III, IV, and VI.

Question 2

Describe the internal anatomy of the eye.

Answer 2

The eye has three concentric coats or layers. The sclera is a tough, protective, white covering, continuous anteriorly with the smooth, transparent cornea. The cornea, part of the refracting media of the eye, covers the iris and pupil. Touching the cornea with a wisp of cotton stimulates a blink referred to as the corneal reflex. Cranial nerves V and VII innervate this reflex. The middle layer contains the choroid, which has dark pigmentation to prevent light from reflecting internally and is highly vascular to deliver blood to the retina. The choroid is continuous with the ciliary body and the iris. The lens, which divides the eye into the anterior and posterior segments, is a transparent structure located behind the pupil. The lens keeps viewed objects in continual focus on the retina. The inner layer contains the retina, which is the visual receptive layer of the eye. In the retina, light waves are changed into nerve impulses.

Question 3

Name the functions of the ciliary body, the pupil, and the iris.

Answer 3

The ciliary body controls the thickness of the lens; the iris serves as a diaphragm, varying the opening at its center; the pupil controls the amount of light admitted onto the retina. The muscle fibers of the iris contract and dilate the pupil.

Question 4

Describe the compartments of the eye.

Question 5

Identify the structures viewed through the ophthalmoscope.

Question 6

Define pupillary light reflex, fixation, and accommodation.

Question 7

Identify age-related changes in the eye.

Question 8

Discuss the three most common causes of decreased visual functioning in the older adult.

Question 9

Incorporate health promotion concepts when performing an assessment of eyes.