Exam 2: Eye Flashcards
Layers of Eye
Fibrous layer (Corneoscleral coat), Vascular Coat (Uvea), Retina
Fibrous layer contains
Cornea and Sclera
Vascular Coat contains
choroid, ciliary body, and iris
Retina contains
Neural and retinal pigment epithelium
Anterior segment is split into
Anterior chamber and posterior chamber
Anterior segment contains
Aqueous humor, iris, ciliary body and muscle, lens, cornea, anterior sclera
Posterior segment contains
Vitreous chamber with vitreous humor, visual retina, RPE, posterior sclera, and uvea
Cornea
anterior 1/6 of eye, continuous with sclera
transparent and avascular
Made of 5 layers
5 layers of Cornea
Corneal epithelium, Bowman’s membrane, Corneal stroma, Descemet’s membrane, Corneal endothelium
Corneal epithelium
stratified squamous (nonkeratinized)
Mitotic activity high to replace injured epithelium
Have microvilli to help retain tears - prevents cornea from drying
Contain ferritin to protect from UV damage
Innervated by ophthalmic division of CN V
Bowman’s membrane (anterior basement membrane)
Acellular basement membrane
Doesn’t regenerate
Terminates at Corneoscleral limbus
Strength and stability of cornea, barrier to prevent against infections
Corneal stroma
middle layer of cornea, 90% of thickness
Collagen fibrils arranged in lamellae at right angle - transparency
Proteoglycans and Collagen V for spacing of collagen fibrils
Descemet’s membrane (Posterior basement membrane)
Basement membrane of cornea endothelium, regenerates after injury, thickens with age, interwoven meshwork of fibers and pores
maintain normal curvature of cornea
Corneal endothelium
faces anterior chamber of eyeball
Simple squamous epithelium with zonula adherens, zonula occludens, and desmosomes
Metabolic exchanges of cornea
Sclera
white of eyeball
posterior 5/6s of eyeball
Tough fibrous connective tissue - maintain shape
Tenon’s capsule
fascial sheath over surfvace of sclera
extraocular muscles insert
Corneoscleral limbus
location of stem cells for corneal epithelium
Location of iridocorneal angle
Uvea (Vascular coat)
Contains Iris, ciliary body, choroid
Iris
most anterior portion of uvea
pupil, anterior and posterior pigment epithelium - give iris color
Contractile diaphragm of front of lens
Dilator pupillae
opens pupil when contracts
Like rays of sun branching out from pupil
Sphincter pupillae
closes pupil when contracts
wraps around pupil
Ciliary body
Anterior to ora serrata
Lined by 2 layers of simple columnar epithelium separated by a basement membrane
Inner layer of ciliary body epithelium
adjacent to aqueous humor, non-pigmented, fluid transporting epithelium
Outer layer of ciliary body epithelium
pigmented - melanin
Ciliary channels
Ciliary Processes
75 radial ridges
Secretion and anchoring of zonule fibers - form suspensory ligament of lens
Produces aqueous humor
Form blood-aqueous barrier
Flow of aqueous humor
Posterior chamber to pupil to anterior chamber to trabecular meschwork to Canal of Schlemm to venous system
Ciliary muscle
longitudinal fibers stretch choroid
Radial fibers flatten lens - distal vision
Circular fibers reduce tension on lens - near vision
Choroid
Dark-brown vascular sheet - prevents reflection of light waves
Lies between sclera and retina
Has two layers - Choriocapillary layer and Bruch’s membrane
Choriocapillary layer
inner vascular layer
richer in small blood vessels -nutrient to retina
Bruch’s membrane
innermost layer of choroid
5 layers:
Basal lamina, Collagen fibers, Elastic fibers, Collagen fibers, Basal lamina of retina
Photosensitive region of retina
Posterior to ora serrata
Vision portion of retina
Optic disc
site where optic nerve joins retina
No photoreceptors - blind spot
Macula lutea and fovea centralis
fovea centralis contains only cones
Macula lutea surrounds fovea
Greatest point of visual acuity on retina
RPE
Pigmented layer Most external layer of retina
below rods and cones - dark background for light to be picked up
Simple cuboidal
Mechanical separation occurs at this junction - detached retina
Layer of rods and cones
Photoreceptive layer
Rods
Most abundant Contains flattened discs Contain rhodopsion and retinal Light hyperpolaizes Low light intensity
Cones
Sensitive to color (red, blue, and green)
Highly concentrated in Fovea centralis
Outer limiting membrane
Apical ends of Muller cells = supportive cells
Between Rod and cone layer and Outer nuclear layer
Outer nuclear layer
Contains nuclei of rods and cones
Outer plexiform layer
Contains synapses between photoreceptor cells, bipolar cells, and horizontal cells
Inner nuclear layer
Contains nuclei of bipolar, horizontal, amacrine, interplexiform, and Muller cells
Inner plexiform layer
Contains synapses between bipolar, ganglion, interplexiform, and amacrine cells
Ganglion cell layer
Contains cell bodies of multipolar ganglion cells
Single layer of cells throughout most of retina - none in fovea centralis, but several layers in macula lutea
Layer of optic nerve fibers
Contains axons of ganglion cells forming the optic nerve
Travels to optic disc
Inner limiting membrane
Basal laminae of Muller cells
Most internal membrane of retina
Lens
Biconvex, transparent, elastic
Avascular, no innervation
Contains type IV collagen fibers and proteoglycans in lens capsule
Cuboidal layer of cells on anterior surface of lens
Conjuctiva
Stratified columnar epithelium with goblet cells
Secretions produce a tear film to protect cornea
