The EYE What a Trip!!! - The Anterior Segment Jill J Luebbert, CPOT, ABOC The Eye The Orbit Bony socket containing the eye and most of its accessory organs consisting of 7 bones 1
The Seven Bones of the Orbit Maxillary largest in inferior wall Frontal largest in superior wall Zygomatic thickest in lateral wall Ethmoid largest medial wall & thinnest Lacrimal Palatine Sphenoid Maxillary Frontal Zygomatic Ethmoid Palatine Lacrimal Sphenoid First three located at front Last ones form the apex in the back Bones are fused together at lines called sutures Eight openings called foramen Some bones have air spaces called sinuses External Structures Eyelids Palpebrae (three functions): REPLENISH and distribute the tear film evenly across the cornea (front surface of the eye) PUMP the tears through the lacrimal sac for drainage from the eye and in this way regulates the amount of tear fluid in the eye PROTECT from light and objects 2
Reflex blinking Forceful closure Blepharospasm Tightly shut and cannot be opened Palpebral aperture - fissure Approximately 10 mm wide Canthus Point which upper & lower lids meet Laterial Closer to ear Medial Closer to bridge of nose Ptosis Ectropian Entropian 3
Eyelids Seven layers of tissue Skin Subcutaneous areolar layer Orbicularis oculi muscle Submuscular areolar layer Levator palpebrae superioris Tarsal plate Meibomian glands Skin layer Outer most layer Thinnest skin of the entire body Contains sweat glands and hair Nasal portion smoother & greasier Begins at gray line Subcutaneous areolar layer Loose connective tissue Contains no fat Demonstrates edema (puffy) 4
Orbicularis Oculi Runs the entire length of the eyelid Responsible for lid closure Controlled by Cranial Nerve VII Submuscular areolar Loose connective tissue Contains majority of nervous and circulatory supply Levator palpebrae superioris Occupies the entire width of lid Is the major muscle responsible for lid opening 5
Tarsal Plate Located in upper & lower lid Made of dense & elastic connective tissue Contains Meibomian glands Produces oil layer of tears Conjunctiva Mucous membrane Begins at gray line Continous across the globe Contains goblet cells to produce mucus layer of tears Contains glands of Krause and Wolfring Produce water layer of tears Hordeolum (Sty) Chalazion 6
Conjunctiva Palpebral Bulbar Fornices Conjunctivitis Blepharitis Lacrimal System 7
Tear Film Three Concentric Tunics Fibrous Vascular Nervous Fibrous Tunic Sclera The white of the eye Provides a rigid protective shell for the intraocular contents while allowing for variations in intraocular pressure Covers 5/6ths of the Fibrous Tunic Cornea Is Avascular 8
Cornea Epithelium Continous with conjunctiva Prevent water from entering the eye Contain nerve endings Bare nerve endings account for corneal sensitivity Quickly regenerates Bowman s Membrane Tough membrane Scars easily 9
Stroma 90% of cornea Comprised of collagen similar to sclera Increase risk of scarring when damaged Descemet s membrane Very thin Does not regenerate when damaged Endothelium Single thickness layer of cells Born with 500,000 cells Does not regenerate cells throughout life Keeps water out of cornea Transports nutrients from aqueous humor to cornea 10
Anterior Chamber The area inside the eye, behind the cornea and in front of the iris Filled with aqueous humor (produced by the ciliary body) Iris Colored portion of the eye- amount of melanin (brown pigment) Divider anterior chamber and posterior chamber - has three layers Stroma Sphincter muscle Dilator muscle Stroma Contains pigment cells Sphincter Muscle (constrictor) Autonomic (nonvolutary) Nervous system Parasympathetic (normal) system Weaker of the two muscles Knocked out with cycloglegic drugs 11
Non-pigmented Epithelium Contains dilator muscle Autonomic (nonvoluntary) Nervous System Sympathetic :flight or flight Knocked out with Mydratic drugs The Journey Continues Thank you! 12
The EYE What a Trip!!! The Posterior Segment Jill J Luebbert, CPOT, ABOC The Eye A Quick Review of the Anterior Segment 13
The Orbit Bony socket containing the eye and most of its accessory organs consisting of 7 bones External Structures Eyelids Palpebrae (three functions): Replenish and distribute the tear film evenly across the cornea (front surface of the eye) Pumps the tears through the lacrimal sac for drainage from the eye and in this way regulates the amount of tear fluid in the eye Protection from light and objects Reflex blinking Blepharospasm Palpebral aperture Ptosis Ectropian Entropian 14
Hordeolum (Sty) Chalazion Conjunctiva Palpebral Bulbar Fornices Conjunctivitis Blepharitis 15
Lacrimal System Tear Film Cornea 16
Any Questions? Let s continue on Posterior Chamber Posterior Chamber The area inside the eye and behind the iris 17
Vascular tunic Iris Ciliary body Choroid Iris Colored portion of the eye- amount of melanin (brown pigment) Divider anterior chamber and posterior chamber - has three layers Stroma Sphincter muscle Dilator muscle 18
Crystalline Lens Nucleus Cortex Capsule Accommodation Cataract Cataract Cilary Body Located behind iris, inside sclera Anteriorly begins at scleral spur Posteriorly ends where joins retina Cilary muscle Responsible for shape of ciliary body Makes up the bulk of ciliary body Stroma Contains blood vessels and ciliary processes Produce aqueous humor 19
Ciliary Muscle Makes up the bulk of the ciliary body Responsible for the triangular shape Responsible for accommodation Controlled by parasympathetic system Can be paralyzed with cycloplegic drugs Accommodation 20
Stroma Contains blood vessels and ciliary process Production of aqueous humor Provides nutrients for lens and cornea Carries aways wastes Choroid Lies between sclera and retina Network of blood vessels, vascular support, supplies oxygen and nutrients Pigment cells (melanocytes) scattered throughout Four layers Hallers Sattlers Choriocapillaris Bruchs Membrane Four Layers Haller s layer Sattlers layer Arterioles and venules Generally considered as one group Choriocapillaries Smaller 21
Bruch s Membrane Thin connective tissue Site of RPE detachments Nervous Tunic Retina Retina Converts light energy into electrical impulses Consists of 10 layers Covers 65% of the interior surface of the eye 22
Retina Begins at Ora Serrata Generally divided into two general sections Outer layer (RPE) Inner layer (Retina) 10 layers Retina Pigment Epithilium (RPE) Neural Retina (rods and cones) External limiting membrane Outer nuclear layer Outer plexiform layer Inner nuclear layerr Inner plexiform layerr Ganglion cell layer Nerve fiber layer Internal limiting membrane 23
Outer layer RPE Regenerates chemicals used to convert light to electrical energy (Vitamin A) Transports nutrients to retina Phagocytize ( eat ) cellular debris Failure to do this is retinitis pigmentosa Begins with night blindness and leads to total blindness Prevents intraocular reflection of stray light Inner layer Neural Retina Nerve cells contain Axon (transmitters) Dendrite (receivers) Communication between cells Synapse Small gap between cells Neurotranmitters The chemical released by axons 24
Inner Segments Photoreceptors: Rods and Cones Rods Tall cylindrical cells (60 mm by 2 mm) Used for motion and vision in low illumination Peripheral Vision Contain Rhodopsin Larger number Are located primarily in the peripheral retina Cones Short cone shaped cells Responsible for pattern detection and fine details Less than rods Cones are located more centrally Fovea Centralis contains only cones Visual pigments sensitive to blue, green and red light (color discrimination) Optic Disc Macula 25
Vision with Macular Degeneration Cable Network Continues 126 million photoreceptors transmit 1 million optic nerve fibers Continues through the visual pathway The Jouney Continues Visual Pathway 26
Thank You!! Enjoy the other courses and activities at Optometry s Meeting 2015 27