Eye Muscle Notes-

Accessory Structures:

Lacrimal Gland-

• Located above eye

• Secrete tears, enzymes

Conjunctiva-

• Thin membrane

• Conjunctivitis= pink eye

The Three Tunics:

• Structural layers of the eye

• Fibrous: Sclera, cornea, aqueous humore

• Vascular: Choroid, ciliary body, iris, pupil, lens

• Sensory: Vitreous humore, retina, optic nerve

Visual Activity:

• Near and far light sources- by tightening the ciliary muscles, allowing the pliable crystalline lens to become more rounded

• Role of the lens

• Accommodation

The Retina:

• Photoreceptors- Rods(Black and White) and Cones(Different colors)

• Fovea centralis-

• Optic disc

Near-sightedness vs. Far-sightedness:

Myopia

• Difficulty seeing far away due to the eye being too long

• Images focus short of the retina

Hyperopia

• Difficulty seeing close up due to the eye being too short

• Images focus behind the retina

Astigmatism:

• When the cornea has an irregular shape

• Part of the field of view is out of focus

• More individuals are affected during nighttime

Floaters:

• When a capillary breaks, and cells break off

• Floaters do not actually move; the eye just tries to track them

• Given eye drops with medication t o break it down faster

• It is an optical illusion, not actually floating

Cataracts:

• Clouding of the lens due to clumping of damaged tissue

• Common, quick procedure for like getting a hip replacement

• The lens is getting old with age

Cataract Surgery, Phacoemulsification:

• Cataract surgery is a safe, common, and highly successful outpatient procedure

• Takes less than 30 minutes to remove a cloudy lens and replace it with an artificial intraocular lens (IOL).

• Does not rely on blood, which is why it has a high success rate

Glaucoma:

• Abnormally high pressure in the eye can press and damage the optic nerve

• Fluid (aqueous humor) fails to drain properly, building pressure that damages the optic nerve.