Eye Anatomy Flashcards
Fibrous Tunic
Layer consisting of sclera and cornea
Vascular Tunic
Layer responsible for nourishment consisting of iris, choroid, and ciliary body
Nervous Tunic
Consists of retina, including rods/cones, neurons
Rods
Do not discriminate between colors (for twilight and dim times)– 120 million rods on retina
Cones
Can distinguish colors, 6 million towards center of macula (the fovea)
Fovea
Center of macula where cones are centralized
Optic Disc
“Blind spot” where optic nerve enters the eye
What are the 3 fluid filled chambers of the eye?
- Anterior chamber
- Posterior chamber
- Vitreous chamber
Anterior chamber
Chamber between cornea and iris filled with aqueous humor
Posterior chamber
Chamber between iris and lens
Vitreous chamber
Chamber between lenses and retina– filled with gel like substance thicker
5 layers of the cornea IN ORDER
- Epithelium: outer most layer
- Bowman’s Membrane: Protective layer
- Stroma: 90% of thickness
- Desemets Membrane
- Endothelium: removes water, keeping cornea clear
Iris
Colored part of eye that controls pupil size
Iris dilator muscle
Opens iris allowing more light in
Iris Sphincter muscle
Closes iris
Ciliary body
muscles that control the movement of the cyrstalline lens
Contracted ciliary body
allows lens to thicken for up close vision
Lacrimal Gland Location
Underneath the outer part of upper eyelid
Lacrimal Gland Function
To produce tears to moisten eye and flush foreign bodies
Nasolacrimal Gland
Drains tears (inner corner of eye)
Function of Eyelids/Eyelashes
To protect against foreign bodies and keep bright light from penetrating eyes, blinking keeps the eye moist over the entire surface
Conjunctiva
thin, transparent layer that protects against bacteria and foreign materials (has visible blood vessels)
Sclera
White layer of eye visible in mirror- tough leather like tissue also extends around back of eye, giving eye the spherical structure
Astigmatism
Causes blurred vision due to irregular cornea shape OR curvature of lens
What causes blurred vision with an astigmatism?
Odd shape causes light to not focus properly on the retina causing blurred vision at any distance
Farsightedness
Hyperopia
Hyperopia
Farsightedness– distant objects seen clearly but close up objects appear blurry
What causes hyperopia?
Eyeball is too short or curvature is too little so light entering eye is not focused properly
Myopia
Nearsightedness– close objects clear but distant objects are blurry
What causes Myopia?
Eyeball to long or curvature of cornea too much
Amblyopia
Lazy eye– caused by development early in life — leading cause of decreased vision among children
Treatment for amblyopia
Glasses, contacts, eye patch therapy
Convergence
eyes unable to work together leading to double vision or blurred vision
Cause of Glaucoma
Damage to the eyes optic nerve, usually inherited and starts later in life