L9 Anatomy of the Eye and Optical Properties Flashcards
Cornea vs. Sclera?
Cornea:
- Transparent (Regular arrangement of collagen fibers)
- Avascular
- Richly Innervated
Sclera:
- Tough Fibrous
- Opaque (IRREGULAR collagenous structure => opacity)
- Provides structure/attachment for extraocular muscles
Three Layers of the Eye
- Fibrous Outer Layer (Outer Layer - Sclera/Cornea)
- Uvea (Middle, Vascualr Layer)
- Retina (Inner, Neural Layer)
Between CORNEA and IRIS is the _________________
Between CORNEA and IRIS is the Anterior Chamber
Contains aqueous humor (Secreted by ciliary epithelium)
Behind IRIS and containing the LENS is the _____________
Behind IRIS and containing the LENS is the Posterior Chamber
Contains aqueous humor (Secreted by ciliary epithelium)
Space behind the lens is the __________________
Space behind lens is Vitreous Chamber
*Acellular (Predominantly water)
- Contains collagen fibers (Clumping => Floaters)
Illustrate the histological appearance of cornea, lens and corneosclerotic junction?
Layers of the Cornea
Components of the Fibrous Layer?
Fibrous Layer (Structural)
- Sclera
- Cornea
Components of the Uvea?
Uvea (Vascular Layer):
- Choroid
- Ciliary Body
- Aqueous Humor
- Iris
- Lens
_________: Loose, vascular, connective tissue
- Between _______ and _________ (from ________ to ________)
- Thickest at ______, thinnest at ______
- Rich in ____________
Choroid: Loose, vascular, connective tissue
- Between RETINA and SCLERA (from optic nerve to ciliary body)
- Thickest at back, thinnest at front
- Rich in Melanocytes!!: Prevents reflection of light within the eye (in tandem w/ pigmented outer retina) vision issues common in albinism, lack pigmentation => light bounces around
_______________: Regulates the shape of the lens
- Lies between ________ and _________
- Connected to LENS BY __________________which emerge from _________________
Ciliary Body: Regulates the shape of the lens
- Lies between CHOROID and IRIS
- Connected to LENS BY SUSPENSORY LIGAMENTS which emerge from CILLIARY PROCESSES
Cornea and Lens are _________ => nutrient supply is via __________________
______________ secrete aqueous humous (w/ Glucose + Amino acids) => drains through TRABCEULAR MESHWORK to __________________
Cornea and Lens are Avascular => nutrient supply is via Ciliary Body
Ciliary Processes secrete aqueous humous (w/ Glucose + Amino acids)=> drains through TRABECULAR MESHWORK to Canal of Schlemm (Scleral Venous Sinus)
Describe the innervation/muscles that control the Pupil
Aperture created by the iris is controlled by TWO muscles under AUTONOMIC control:
Sphincter Pupillae (Closes):
- Contracts=> shrinks aperture, limiting amount of light entering eye
- Parasympathetically innervated. BLOCKED BY ATROPINE => Dilation
Dilator Pupillae (Opens)
- Contracts => opens aperture, allows more light to enter the eye
- Sympathetically Innervated
__________________:
- Clear elastic layer produced by ______________
- Composed of collagen and glycosaminoglycans
- Under constant tension => affects lens shape
LENS CAPSULE (LC):
- Clear elastic layer produced by LENS EPITHLIUM
- Composed of collagen and glycosaminoglycans
- Under constant tension => affects lens shape
_____________________:
- lens homeostasis (produces _______________)
- osmotic control
LENS EPITHELIUM (LE):
- lens homeostasis (produces LENS CAPSULE)
- osmotic control
____________________:
- Long, thin transparent cells arranged in laminae
- Oldest cells are found in ________:(Contain no organelles/nuclei)
LENS FIBERS (DLF):
- Long, thin transparent cells arranged in laminae
- Oldest cells are found in CENTER (Contain no organelles/nuclei)
Relationships of:
- Focal Length
- Curvature of the Lens
- Refractive Power (Diopters)
Rays from more than __________ away are considered to be traveling in parallel
Focal Length = 1/2 radius of Curvature
Refractive Power: Measured in Diopters (D) => D= 1/Focal Length
- More Diopters= More Bending of Light
Rays from more than 6 meters away are considered to be traveling in parallel
Retinal layer is perforated by optic nerve on ______ Side of the eye
Retinal layer is perforated by optic nerve on the NASAL SIDE of the eye
_________________ pigmented area in center of optical axis containing the FOVEA at center and has ________ or more layers of retinal ganglion cells
MACULA LUTEA: pigmented area in center of optical axis containing the FOVEA at center and has TWO or more layers of retinal ganglion cells
Structure of the Retina:
○ ___________________(Cell bodies of Ganglion cells)
○ ____________________( Synapses b/n Bipolar Cells and Ganglia)
○ ____________________(Bipolar Cell Bodies)
○ _______________________(Synapses b/n Bipolar Cells & Photoreceptors)
○ _____________________(Photoreceptor Cell Bodies)
○ _____________________________(Area where light is sensed)
○ ______________________(Prevents reflection within eye)
Structure of the Retina:
○ Ganglion Cell Layer (Cell bodies of Ganglion cells)
○ Inner Plexiform Layer ( Synapses b/n Bipolar Cells and Ganglia)
○ Inner Nuclear Layer (Bipolar Cell Bodies)
○ Outer Plexiform Layer (Synapses b/n Bipolar Cells and Photoreceptors)
○ Outer Nuclear Layer (Photoreceptor Cell Bodies)
○ Outer Segments of Photoreceptors (Area where light is sensed)
○ Pigment Cell Layer (Prevents reflection within eye)
Where does the majority of refraction in the eye occur? Why?
Total Refractive power of the Eye?
Majority of refraction takes pace at the CORNEA (Has air on one side, aqueous humor on the other):
Refractive power of the eye is 59 Diopters:
- CORNEA: 43D
- LENS: 16D
Shape of Lens Accomodation for NEAR vs. FAR target?
What innervates the CIlliary Body?
Oculomotor (CN III) Parasympathetic Fibers
Sympathetic Fibers from Cervical Ganglia
Disc like projection of CILIARY BODY in front of LENS?
Iris
What attached the CIlliary Body to the Lens?
Zonular Fibers
Describe the process of Accommodation
Relaxed Ciliary Body: exerts tension on Zonular Fibers attached to Lens Capsule => Lens Flattens (Far in Focus)
Accommodated (Contracted) Ciliary Body: slides forward relaxing Zonular Fibers => Lens Expansion (Near in Focus)
Contribution of the Pupil to Accommodation?
Depth of field is smaller at smaller focal distances
Smaller pupil => GREATER depth of field
Pupil constricts when object brought close
Accommodative response to focus on NEAR Object?
Accommodated (Contracted): Ciliary Body slides forward relaxing Zonular Fibers => Lens Expansion (Near in Focus)
Pupil Constricts => GREATER depth of field
Accommodative response to focus on FAR Object?
Relaxed Ciliary Body exerts tension on Zonular Fibers attached to Lens Capsule => Lens Flattens (Far in Focus)
What is the Refractive Error called?
Myopia: Nearsightedness
What is the Refractive Error called?
Hyperopia: Farsightedness
Loss of accommodation power w/ age due to loss of lens elasticity
Presbyopia
Misalignment of the eyes (“Cross-eyes”)
Strabismus (Heterotropia)
Results from irregular curvature of the cornea or lens
Astigmatism
