Visual Tracts (Dennis) Flashcards
What are the tunics/layers of the eye
Fibrous Layer
Vascular Layer
Retina
What layer of the eye touches the external layer
What does it consists of?
Fibrous layer
The sclera and cornea
What layer of the eye consists of the choroid, ciliary body and iris
Vascular layer
What is the inner sensory layer of the eye that gives rise to the optic nerve
Retina
What is the sclera
What is the tissue type
Fibrous, external layer of the eyeball that protects internal structures and provides sites for muscle insertion.
Dense regular CT, with flat bundles of type I collagen and microvascular near the outer surface
List the layers of the cornea
- Corneal epithelium
- Anterior limiting membrane (Bowman membrane)
- Stroma comprised of keratocytes
- Posterior limiting membrane (Descemet’s membrane)
- Inner endothelium
What is the transitional area where the transparent cornea merges with the opaque sclera and encircles the entirety of the cornea
Limbus
What are the layers of the retina and what are the cell types attributed to them
- Outer Pigmented layer: Simple cuboidal epithelium
- Inner Neural layer: Thick and stratified with various neurons and photoreceptors
Neural components of the retina extend anteriorly to where
Ora Serrata
What are the functions of the pigmented epithelium (PE)
- Absorbs scattered light
- Forms part of the blood-retina-barrier
- Isomerizes all-trans-retinal to 11-cis-retinal and transfers back to photoreceptors
- Phagocytosis & degeneration of waste from photoreceptors
- Removes free radicals & secretes ATP, polypeptide growth factors & immunomodulatory factors
What are the layers of the Neural Retina from superficial to deep?
- Inner limiting membrane (ILM)
- Optic nerve fiber layer (NFL)
- Ganglionic layer (GL)
- Inner plexiform layer (IPL)
- Inner nuclear layer (INL)
- Outer plexiform layer (OPL)
- Outer nuclear layer (ONL)
- Outer limiting layer (OLL)
- Photoreceptors: Rod & cone layer (RCL)
- Pigmented layer (PL) - not actually part of NL
Mnemonic: In Our God IIs Ooour Pure Purpose
What are the function of the inner and outer segments of rods
Inner segment: contains glycogen, mitochondria and polyribosomes for the cell’s biosynthetic activity
Outer segment: Contacts the pigmented epithelium and contains flattened membranous discs that contain rhodopsin
Iodopsin
The visual pigment contained by cones
What is the Fovea Centralis
Area in retina with the highest concentration of cones, making it the area where visual acuity is sharpest. Absence of vessels, cell bodies and axons of ganglionic and inner nuclear layer
What is the Macula Lutea
Surrounds the fovea and protects cones. Has antioxidant properties and short wave UV filter.
Characteristics of the optic disc
Located at head of optic nerve where ganglion axons from all of the retina converge and dive. Lacks photoreceptors so it’s a blind spot
What is the optic nerve
Axons of retinal ganglion cells that become myelinated as they pass through the sclera and penetrate the chroroid as it travels to the brain.
What is the name for the areas that a person is able to see when both eyes are fixed in one position
Visual fields
Binocular zone
The broad central region seen by both eyes