Exam #2: Eye Flashcards
What are the three layers of the eye?
1) Fibrous/ Corneoscleral
2) Vascular/ Uvea
3) Retina
Corneoscleral Layer of the Eye
- Most superficial part
- Cornea= anterior 1/6
- Sclera= posterior 5/6
Where does the uvea get its blood supply from?
Ophthalmic Artery
Vascular Layer of the Eye/ Uvea
Iris= anterior, eyecolor Choroid= posterior, dark heavily pigmented portion
Retinal Layer
- Neural/ innermost layer of the eye
- Anterior= thin & nonvisual
- Posterior= thin & visual
What marks the separation between the anterior & posterior portion of the retina?
Ora Serrata
What are the different chambers of the eye?
- Eye is divided into an anterior & posterior segments by the Ora Serrata
- Anterior segment is further divided into the anterior & posterior chambers by the iris
- Posterior segment contains the vitreous chamber
Contents of the Anterior Segment
- Aqueous Humor
- Iris (vascular)
- Ciliary Body & Muscle
- Lens (avascular)
- Cornea (avascular)
- Anterior Sclera
Contents of the Posterior Segment
- Vitreous Humor
- Visual Retina
- RPE
- Posterior Sclera
- Uvea
Aqueous Humor vs. Vitreous Humor
- Aqueous= anterior chamber, provides stability & nutrition to keep the avascular structures alive
- Vitreous= vitreous chamber (posterior segment), more jelly-like than aqueous humor b/c of 1% collagen)
What does dehydration of the vitreous humor lead to?
- Detached retina
- The vitreous humor helps keep the retina on the vascular layer & choroid
Cornea
- Anterior 1/6 of the eye
- Transparent
- Avascular
- Provides 2/3 of the refractive power of the eye (more than lens)
What are the five layers of the cornea from outside to inside?
1) Corneal Epithelium
2) Bowman’s Membrane
3) Corneal Stroma
4) Descemet’s Membrane
5) Corneal Endothelium
Corneal Epithelium
- Stratified squamous epithelium (non-keratinized)
- Contains microvilli (prevent drying out)
- Contains Ferritin (protects from UV damage)
- Regenerates
- Blink reflex (CN V & VII)
Bowman’s Membrane
- Anterior basement membrane
- Does not regenerate–> scarring
- Provides strength to the cornea
- Barrier to infections
- Terminates at corneoscleral limbus
Corneoscleral limbus
- Transition point of cornea & sclera
- Contains stem cell for the corneal epithelium
Corneal Stroma
- Also called the Substantia Propria
- 90% of corneal thickness
- Contains proteoglycans & type V collagen organized in 90 degree lamellae
Descemet’s Membrane
- Posterior basement membrane
- Regenerates
- Thickens with age
- Helps maintain normal curvature of the eye through pectinate ligaments
Pectinate Ligaments
Connect the sclera to the ciliary body & help maintain the normal curvature of the eye
Corneal Endothelium
- Simple squamous epithelium
- Joined by zonula adherens, zonula occludens, & desmosomes
- Adjacent to aqueous humor
- Limited proliferative ability
- Responsible for nearly all metabolic exchanges of the cornea & contains fluid pumps for hydration
Sclera
- Posterior 5/6 of the eyeball
- “White” of the eye
- Contains though fibrous connective tissue (Collagen & Elastic Fibers)
What are the three layers of the sclera?
1) Episcleral
2) Substantia Propria
3) Suprarachnoid Lamina
Episcleral Layer
- Outer layer of the sclera
- Contains tenon’s space
Tenon’s Space
A space between tenon’s capsule & periorbital fat that gives the eye room to move in
Substantia Propria
- Intermediate layer of the sclera
- Contains Tenon’s Capsule
Tenon’s Capsule
Connection to the extra-ocular muscles
Suprarachnoid Layer
- Inner layer of the sclera
- Attachment of the sclera to the choroid
- How the sclera gets nutrients
Iridocorneal Angle
Corner of the cornea & iris
Canal of Schlemm
Scleral venous sinus i.e. apparatus for outflow of aqueous humor
Contents of the Uvea
1) Iris
2) Ciliary Body
3) Choroid
Iris
- Most anterior portion of the uvea
- Color part of the eye (no pigment= pink)
Pupil
Opening between the two edges of the iris