Chapter 15: Eyes
● Eye: only a small portion of the eye is seen → 3 layers
○ Sclera- made of a fibrous material that can help the eye to keep its shape;
■ Can indicate presence of jaundice (yellowing)
■ Contains the
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Chapter 15: Eyes
● Eye: only a small portion of the eye is seen → 3 layers
○ Sclera- made of a fibrous material that can help the eye to keep its shape;
■ Can indicate presence of jaundice (yellowing)
■ Contains the cornea- protection in front of lens; can repair itself
○ Choroid- middle layer
■ Iris- colored part of the eye; can constrict or dilate the pupil
■ Pupil- center of the iris; opening for light to travel into the eyes
● Mydriasis- when dim light enters, and the pupil enlarges
● Miosis- bright light enters, making the pupil constrict
○ Retina- where the optic nerve should be gathered
■ Optic disc- blind spot: red free filter helps see optic disc
■ Macular- responsible for central vision
● Refraction of the eye- light travels in a straight line
○ Cornea → refracts and directs through pupil and into eye
○ Emmetropia- normal refractive condition of the eye;
■ Focal point → RIGHT ON retina
○ Myopia (nearsightedness)- light rays focus in front of the retina
■ Can see close, but have difficulty seeing far away : 12-14 in away from paper
○ Hyperopia (farsightedness)- light rays focus behind the retina
■ Can see fine from far away but have a difficulty seeing close up
○ Hemianopsia- portion of the visual field would not be seen due to a lesion
● Accessory structures of the eye
○ Eyebrows- protect the eye
○ Eyelids (palpebrae) - moveable folds of skin that cover and protect
■ Palpebral fissure- opening between upper and lower eyelids
■ Meibomian glands- oily substance that helps lubricate the eyes
○ Eyelashes- protect from eyelids and curl outward
○ Conjunctivae- prevents foreign bodies from entering the eye
○ Lacrimal apparatus- tears are secreted
● Extraocular muscles: cranial 3, 4, 6
○ Cardinal fields of gaze → assess whether there are any deviations
● Lifespan considerations:
CONTINUED........
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