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277 Cards in this Set
- Front
- Back
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The muscles of the iris are derived from
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Neural ectoderm
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The pars plana functions to
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Restore MPS important to the vitreous
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The pars plicata functions to
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Make aqueous via active transport
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Layers of the irisAnterior border layerStromaAnterior epithelium and dilator musclePosterior pigmented epithelium
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Part you seeContains sphincter muscleOne cell layerOne cell layer
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The dilator muscle consists of
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Radial extensions of the unpigmented anterior epithelium
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Longitudinal fibers of the ciliary muscle
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Arise from anterior choroids and run to the scleral spur
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Circular fibers of the ciliary muscle form a
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Sphincter around the edge of the CB behind the iris root
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Radial fibers of the ciliary muscle form a
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Meshwork between the longitudinal and circular fibers
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1st synapse of the light reflex pathway occurs in the
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Pretectal nucleus
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2nd synapse of the light reflex pathway occurs in the
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EW nucleus
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3rd synapse of the light reflex pathway occurs in the
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Ciliary ganglion
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From the ciliary ganglion the signals travel down
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Short ciliary nerves to the iris sphincter of both eyes
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For eyes to dilate, the lack of light sends a signal to
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Lateral geniculate body (synapse)
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From the LGB the signal travels to the
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Cortex (synapse) and hypothalamus and reticular formation
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The final synapse for pupil dilation is in the
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Superior cervical ganglion
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From the superior cervical gangion the signal goes
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Through the long ciliary nerves to the iris dilator
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During sleep the pupil
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Constricts
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Stages of anesthesiaStage 1Stage 2Stage 3Stage 4
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Excitatory phase – pupil dilationLight anesthesia – pupil dilationDeep anesthesia – pupil constrictionNear death – pupil dilation
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Corneal pain causes the pupil to
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Constrict – oculopupillary/trigeminal reflex
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Prolonged pain causes activation of the
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Sympathetic nervous system – pupil dilation
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Systemic pain causes the pupil to
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Dilate
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Number of lashes on upper lid
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100-150
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Number of lashes on lower lid
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50-80
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The tarsal plates are made of
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Fibrous and elastic tissue – NO cartilage
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Meibomian glands are located in the
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Tarsal plates
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Blood supply to the eyelids Facial system Orbital system
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External carotid A > facial A > angular A External carotid A > internal maxillary A > intraorbital ASuperficial temporal AInternal carotid A > ophthalmic A > dorsal nasal A, supratrochlear A, supraorbital A, lacrimal A
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Venous drainage of the eyelids Facial system Orbital systems
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Angular V > anterior facial V > external jugular V Superior temporal V > retiromandibular vein > external jugular VInfraorbital V > pterygoid venous plexus >internal maxiallary V >external jugularSupraorbital V, Supratrichlear V > superior ophthalmic V > cavernous sinus > internal jugular VLacrimal V > Inferior ophthalmic V > cavernous sinus > internal jugular VAnterior facial V
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Lymphatic drainage of the eyelids and conjunctiva Medial portion of eyeLateral portion of eye
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Submaxillary or submandibular nodes Preauricular or parotid nodes
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Ophthalmic division of CN V receives sensory info from
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Upper eye lid
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Maxillary division of CN V receives sensory info from
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Lower eye lid
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Accessory lacrimal glands of Kraus and Wolfring are
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Located in the conjunctiva – secrete serous/ aqueous fluid
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Blood supply to the conjunctiva is through the
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Peripheral arteriole arcades, marginal arteriole arcades and the anterior ciliary artery
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Venous drainage of the conjunctiva is through the
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Superior and inferior palpebral plexus
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Sensory innervation to the conjunctiva is by the
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Supratrochlear and Infratrochlear branches of CN V
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Corneal diameter
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Anterior. 11.7mm (horizontal) 10.6mm (vertical) Posterior 11.7mm circular
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Corneal radius of curvature
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Anterior 7.8mm, Posterior 6.5mm
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Corneal thickness
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Central 0.52mm, peripheral 0.67mm
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5 layers of the cornea Epithelium Bowman’s layer Corneal stroma Descemet’s membrane Endothelium
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Central 5mm has the greatest nerve density Cornea is 72-82% water50um (10% of corneal thickness) – continuous with conjSurface cells with microvilli – Wing cells –polygonal cellsBasal cells – germinal layer – regenerates epithelium Basal lamina – between basal cells an Bowman’s – regeneratesCellular fibrous tissue, made of MPS and GAG –not a true membrane – indistinguishable from stroma – CANNOT regenerate –90% corneal thickness (470um)Lamellae (200-250 – each 2um thick) – half life of each lamella is 100 days – lamellae are held in place by MPS and glycoproteins (ground substanceCells 2-5% stromal volume – fibroblasts synthesize collagen and MPS and bind lamellae in their ordered position – Schwann cells make up nerve sheaths – lymphocytes and macrophages aka posterior limiting membrane – true basement membrane for endothelium – ends at Schwalbe’s line – cen regenerate – sharp differentiation from stroma – made of collagen, MPS and GAGs – thickens with age – not innervatedsingle layer of hexagonal cells – synthesizes Descemet’s membrane – microvilli protrude into anterior chamber – very metabolically active – not innervated – regeneration limited
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Hassal Henle warts are
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Localized thickening in the peripheral cornea – seen as dark spots of holes in the endothelium
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Radius of curvature of the sclera is
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11mm
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The sclera is thinnest
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Posterior to the insertion of the recti muscles (0.3mm)
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The sclera is thickest near the
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Optic nerve (1.0mm)
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Sclera contains
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65% water
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Tenon’s capsule is between the
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Conjunctival stroma and underlying episcleral tissue
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Episcleral space is the potential space between
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Tenon’s capsule and the episclera
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Suprachoroidal space is between the
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Sclera and choroid and is where the long and short posterior ciliary nerves travel
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Three layers of the sclera EpiscleraScleral stromaLamina fusca
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Dense, vascular connective tissue Bundles of collagen and fibroblasts and ground substanceIncreased pigment
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Volume of the anterior chamber
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0.25ml
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Anterior chamber depth
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Women 3.41- 3.65mm – men 3.61-3.70mm
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The internal scleral sulcus is mostly occupied by
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Trabecular meshwork
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The Apex of trabecular meshwork is located near
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Schwalbe’s line (end of Descemet’s) – 3-5 layers thick
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The Base of trabecular meshwork is formed by the
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Scleral spur and the ciliary body – 15-20 layers thick
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3 sections of trabecular meshwork Corneoscleral meshwork Uveal meshwork Pectinate fibers
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Flat fenestrated sheets of tissue – filtering holes called intratrabecular spaces – larger holes are called “spaces of Fontana”, decrease in size toward Schlemm’s canal Most internal component – most anterior extension of the uvea – aka uveal “chords” – Aka iris processes – extend from iris root to the uveal meshwork – bridge the ACA – about 100 present per eye
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Schlemm’s canal is a
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Circular venous channel – lies on the outer portion of the internal scleral sulcus
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Internal collecting channels of Schlemm’s canal are
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Internal collector channels of Sondermann
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Aqueous flow…
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Trabecular meshwork (diffusion) > Schlemm’s canal (active transport) > deep scleral plexus > intrascleral venous plexus > aqueous veins of Asher > episcleral veins > anterior ciliary veins
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The inner wall of Schlemm’s canal is called the
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Justacanalicular tissue – lined with endothelium
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The iris is thickest at the
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Collarette (0.6mm) site of minor arteriole circle of the iris
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Diameter of the iris =
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12mm
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Circumference of the iris =
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37.5mm
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The only pigment found in the iris is
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Melanin
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Blood supply to the iris Major arterial circle Minor arterial circle
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In the ciliary body along iris border – anastomoses between Anterior ciliary and Long Posterior ciliary arteries Located at the level of the collarette – formed by radial branches from the major circle
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Microscopic anatomy of the iris Anterior border layer Stroma Sphincter muscleAnterior epithelium Dilator musclePosterior pigment epithelium
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Condensation of stromal tissue – fibroblasts and melanocytes – few collagen fibers Loose collagenm ground substance, elastin – continuous with CB stroma – melanocytes, lymphocytes, fibroblasts, mast cells – Clump cells (pigmented macrophages in papillary region)In pupillary portion of the stromaContinuous with the external pigment epithelium of the CB – contains myoepithelial cells – muscular processes make up the dilator muscle Developed from and an integral part of the anterior epithelium Single row, heavily pigmented columnar epithelial cells – basal surface contacts aqueous humor of post chember
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Posterior chamber volume =
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0.06ml (decreases with accommodation and dilation)
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3 divisions of the posterior chamber Posterior chamber properZonular portion (Canal of Hanover)Retrozonular portion
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Posterior to iris – anterior to lens zonules Space between zonule fibersPosterior to zonules – anterior to anterior hyloid of vitreous
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The Pars plana (orbicularis ciliaris )portion of the CB
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Runs from ora to ciliary processes -
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The Pars plana produces
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MPS for vitreous
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The Pars plicata (corona ciliaris) produces
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Aqueous humor
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Layers of the CB include Unpigmented epithelium pigmented epitheliumstroma supraciliaris
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Most internal layer – one cell thick – continuous anteriorly with the pigmented epithelium of iris and posteriorly with the nervous retina at ora Continuous anteriorly with unpigmented epithelium of iris and posteriorly with RPE at ora – thickens with ageInner connective tissue layer – loose tissue external to the basement membrane – collagen, blood vessels, nerves, fibroblasts and mast cells – contains ciliary muscle Most external layer – lies next to lamina fusca of sclera – fibroblasts and melanocytes
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The ciliary stroma becomes choroids at the
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Ora serrata
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At ora the supraciliaris of the CB becomes the
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Suprachoroid
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At ora the external pigmented epithelium of CB
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Becomes pigmented epithelium of the retina
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The unpigmented epithelium of CB becomes
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Nervous retina
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Blood supply to the CB includes
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2 long post ciliary As and 7 anterior ciliary As
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3 portions of the ciliary muscle Longitudinal portion Radial portion Circular portion
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(aka Brucke’s muscle, Meridional fibers) – origin at SS – insertion into choroid (epichoroidal muscle stars) – moves choroid anteriorly (oblique fibers) – origin SS – insertion at ciliary processes and Pars Plana – pulls pars plana anteriorly (aka Mueller’s muscle, Ciliary sphincter) – origin SS – insertion into anterior part of ciliary processes – constricts lens aperture
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Zonules originate in the
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Pars plana
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The anterior Y suture is
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Erect
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The posterior Y suture is
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Inverted
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Y sutures are found in what area of the lens
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Fetal nucleus
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Lens epithelium is present at the
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Equator and anteriorly under the capsule – NOT posteriorly
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How many lens fibers are there in an adult lens?
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2000
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Large blood vessels in the stroma of the choroid are
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Haller’s vessels
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Small blood vessels in the stroma of the choroid are
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Sattler’s vessels
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Anterior ½ of choroid is supplied by
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2 long posterior ciliary As to major arterial circle of the iris
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Posterior ½ of choroid is supplied by
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Many short posterior clilary As – form the circle of Zin-Haller
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The choroid is mainly drained by the
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4 vortex veins
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Anterior ciliary veins drain the
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Anterior ½ of the choroid via the limbal plexus
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Pial veins drain the
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Optic nerve meninges and part of the posterior choroid
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Bruch’s membrane is the innermost layer of the choroid
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Adjacent to the RPE
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Layers of Bruch’s membrane Basement membrane of RPEInner collagenous zoneElastic layerOuter collagenous zoneBasement membrane of choriocapillaris
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Actually a retinal layer (0.3um) No nerves no cells (1.5um)Backbone of Bruch’s membrane (0.8um)Fibroblasts, no nerves (0.7um)Outermost layer (0.14um)
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The volume of the vitreous is
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4ml
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Vitreous attachments Vitreous basePeripapillary attachmentMacular attachmentHaloideocapsulary ligament
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Firmest (2mm forward on CB and 4mm onto retina) Loosens with age4mm centered around fovea (Maxwell’s spot)Weigner’s or pectinate ligament – around post lens surface
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The area of Martegiani is the area around the
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ON where Cloquet’s canal flares out
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Cloquet’s canal is a remnant of
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Primary vitreous (hyaloid artery)
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Layers of the retina RPE PhotoreceptorsExternal limiting membraneOuter nuclear layerOuter plexiform layer Inner nuclear layerInner plexiform layer Ganglion cell layerNerve fiber layerInternal limiting membrane
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Uniform single layer of hexagonal shaped cells – more pigment in the macular region Thin, fenestrated layerCell bodies of rods and cones – nuclei and cytoplasmPhotoreceptor axons synapse with bipolar and horizontal cells – Muller cells fill in and have a nutritive functionCell bodies of horizontal, bipolar, Muller and amacrine cells Synapses between bipolar cells (1st order neuron) , amacrine cells and ganglion cells (2nd order neuron)Cell bodies of ganglion cellsAxons of ganglion cells Lines the vitreous face of the retina
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In cases of retinal detachment the RPE…
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Stays connected to Bruch’s membrane
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The RPE provides photoreceptors with
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Vitamin A, glucose and oxygen
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Horizontal cells make connections between
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Photoreceptors and other horizontal cells
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Amacrine cells make connections between
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Different ganglion cells
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Photoreceptor layers receive blood from the
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Choroid (outer nuclear and plexiform)
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Inner retinal layers are supplied by the
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Central retinal artery
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Area centralis is located
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4mm temporal and 0.08mm inferior to the optic disc
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The perifovea is
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1.5mm in width and 2.25mm from the fovea
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The largest accumulation of nerve cells in the retina is
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In the parafovea (2.1mm in width) around the fovea
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The parafoveal layer has a thick
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Outer plexiform layer (layer of Henle)
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The fovea is
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1.5mm in diameter – receptor layer has CONES ONLY
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The foveola is
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0.35mm across and contains only photoreceptors and glial cells
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Ora serrata is located measures
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8.5 mm from limbus…6mm from equator…25mm from ONH 2.1mm temporally…0.8mm nasally
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The prelaminar portion of the optic nerve is protected by
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Astrocytes that make up the intermediary tissue of Kuhnt, glial mantle of Fuchs or Graefe and the border tissue of Jacoby
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The inner limiting membrane of Elschnig is where
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The glial layer thickens over the ONH
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The Meniscus of Kuhnt is where
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Elschnig fills the optic cup
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Nasal macular fibers cross at the
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Center of the optic chiasm
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The fist contact of the optic tract with the brain is the
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Cerebral pedulcles
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The optic tract divides sending the lateral part to the
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LGN and the medial part to the superior colliculus and pretectum
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Superior retina sends info to the
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Medial part of the LGN
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Interior retina sends info to the
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Lateral part of the LGN
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The cuneus (above calcarine fissure) maps the
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Lower visual field (superior retina)
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The lingual gyrus (below the calcarine fissure) maps
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Superior visual field (inferior retina)
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Layers 1,4,6 of the LGN are
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Contralateral, nasal hemiretina, temporal crescent
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Layer 2,3,5 of the LGN are
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Ipsilateral, temporal hemiretina
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Layer 4C alpha of the visual cortex has the
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Ocular dominance columns
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All ocular tissues develop from 3 embryological layers
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Neural ectoderm, surface ectoderm and mesenchyme
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Retinal layers derive from
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Neural ectoderm
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The optic cup is formed by the invagination of
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Neural ectoderm
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The innermost layer of the optic cup forms the
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Inner and outer neuroblastic layers
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The inner neuroblastic layer forms the
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Ganglion cells, amacrine cells and Muller cells
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Outer neuroblastic layer forms the
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Bipolar cells, photoreceptors and horizontal cells
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The outermost layer of the optic cup becomes the
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RPE
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The anterior part of the optic cup forms the
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Epithelium of the ciliary body and posterior surface of iris
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The inner (posterior) pigmented layer of the iris is
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Continuous with the non pigmented layer of the CB epithelium
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Outer lightly pigmented layer of iris is continuous with
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The pigmented layer of the CB epithelium
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The iris dilator and sphincter develop from the
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Outer lightly pigmented layer of iris epithelium (neural ectoderm)
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Surface ectoderm is induced to form the lens placode
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By close association with the optic vesicle (neural ectoderm)
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After the lens sack detaches the surface ectoderm
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Continues on to form the eye lids
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Surface ectoderm also forms the accessory glands of
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Krause, Zeiss, Wolfring, Moll and meibomian glands
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The lacrimal glands and drainage system also come
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From the surface ectoderm
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Anything that tears touch comes from the
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Surface ectoderm
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Mesenchyme originates from both
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Neural crest and mesoderm
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The hyaloid A and V are formed when
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Mesenchyme enters through the embryonic/choroidal fissure
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Corneal epithelium and primary stroma are formed by
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Surface ectoderm
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Corneal endothelium is formed by
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The first wave of neural crest mesenchyme (7th wk)
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The future corneal stroma is formed by the
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Second wave of neural crest mesenchyme (8th wk)
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Ciliary muscles are formed from
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Mesenchyme
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Vascular choroid and tough sclera are formed from
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Mesenchyme
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The EOMs are derived from
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Mesenchyme
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The bones of the orbit are formed from
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Mesenchyme
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Most bone sutures in the orbit close at
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6-7 months
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The sphenoid bond suture closes at the end of
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The first year
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SR, SO and levator develop from the
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Superior mesoderm condensation
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IR and IO develop from the
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Inferior mesoderm condensation
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MR and LR develop from
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Both condensations
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CN III, IV and VI evolve in the
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Cranial portion of the neural tube (III 4th wk)(IV 7th wk)(all 8th wk)
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The skin lids, glands and conjunctiva develop from
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Surface ectoderm
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The tarsal plate, orbicularis oculi, levator aponeurosis and smooth muscle of the eye lid are from
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Mesoderm
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Tearing begins
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20-104 days after birth -
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The lacrimal gland is fully developed at
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3-4 years of age
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The cornea will not develop is
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The optic cup is missing
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Corneal stroma, Descemet’s corneal endothelium and Bowman’s layer are derived from
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Neural crest mesenchyme
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Corneal nerves enter the tissue at
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3 months – approach the epithelium by 5 months
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Arborization of corneal nerves occurs in the stroma
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Between the 6th and 9th months
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Corneal diameter at birth =
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10mm
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Adult corneal diameter =
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12mm
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At birth the corneal curvature is
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Flatter than the adults
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The sclera develops from
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Mesoderm
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The lamina cribrosa forms at the
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6th month
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The third wave of neural crest mesenchyme forms
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Iris stroma
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The anterior chamber is present by the
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5th month
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Iris stroma is derived from
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Neural crest mesenchyme during the 4th month
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The pupil is fully formed by
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8 months
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If pupillary atrophy fails you see a
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Persistent pupillary membrane
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The ciliary muscle comes from
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Mesoderm
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The epithelial layers of the ciliary body come from
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Neural ectoderm of the optic cup
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The lens zonules develop from
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Tertiary vitreous (neural ectoderm) (neuroepithelium of CB)
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Primitive lens fibers are found at
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The exact center of the lens throughout life
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The embryonic nucleus is made up of
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Primary lens fibers – optically clear central area (months 1-3)
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The fetal nucleus is made of
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Secondary fibers (3-8 mo fetal life)
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Infantile nucleus is laid down beginning in the
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Last weeks of fetal development and continuing to puberty
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Adult nucleus is formed after
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Puberty
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The choriocapillaris is complete by the
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6th week of development
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The choriocapillaris is supplied by the
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Short post ciliary As which branch off the long post ciliary As
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Bruch’s membrane is composed of an
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Inner ectodermal layer and an outer mesodermal layer
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The primary vitreous contains the
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Hyaloid artery
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The secondary vitreous is
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Avascular
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The secondary vitreous is derived from
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Neural ectoderm
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Stages of retinal development Stage 1 Stage 2 Stage 3
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Epithelial stage – retina develops from pseudostratified neuroepithelium Two zonesOuter primitive zone – inner and outer neuroblastic layersInner marginal zone – initially contains so nuclei – cells frominner neuroblastic layer migrate to itDifferentiation of the nervous elements – 1st ganglion cells then rod and cone photoreceptors
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Muller cells extend from
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The ELM to the ILM
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Macular development is complete
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3-4 months after birth
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Retinal circulation during development involves Primitive dorsal ophthalmic A Ventral ophthalmic A
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-branches from the internal carotid A -annular vessel at rim of optic cup-temporal long ciliary A – form the major arterial circle-anterior ciliary A -branches from the internal carotid A-anastomoses with dorsal ophthalmic A -develops into the nasal long ciliary A-degenerates
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The hyaloid A is a branch of the
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Primitive dorsal ophthalmic A
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As the hyaloid system atrophies the
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Central retinal A is formed – also the central retinal V
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The optic nerve is surrounded by
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All three layers of meninges of the brain
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The macula gives rise to
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1/3 of the optic nerve fibers (10% of retinal space)
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The intermediary tissue of Kuhnt is composed of
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Neuroglia
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Perfusion pressure of retinal vessels =
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MAP – IOP
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Alpha 1 adrenergic receptors cause
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Constriction of blood vessels
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Beta 2 adrenergic receptors cause
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Dilation of blood vessels
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There is NO parasympathetic innervation to
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Blood vessels
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Forced closure of eye lids =
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Orbital portion of the Orbicularis oculi (CN VII)
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Spontaneous blinking and voluntary winking =
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Palpebral portion of the orbicularis oculi
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The menace reflex is a
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Cortical reflex – afferent pathway is through the ON
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Touch reflex involves…
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CN V afferents and CN VII efferents
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Glands of Krause are located in the
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Conjunctival fornices
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Glands of Wolfring are located along the
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Tarsal plate
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Dehydration of the cornea is mainly done by the
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Endothelium
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Partial pressure of oxygen – eyes open
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155 mmHg
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Partial pressure of oxygen – eyes closed
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55 mmHg
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The epithelium regenerates completely every
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7 days
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Hassel Henle bodies are
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Localized thickenings of Descemet’s membrane (aging change)
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Systemic acidosis with
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Lower IOP
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Index of refraction of aqueous
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1.336
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The energy needed by the lens epithelium comes from
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Anaerobic glycolysis (used for active transport)
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Soluble lens crystallines found in the cortex include
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Beta cyrstalin 55% - alpha crystalin 15% - gamma crystalin 15%
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Insoluble proteins of the lens nucleus include
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Albuminoid
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The lens has high amounts of
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Glutathione
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Retinal is an
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Unsaturated aldehyde formed by oxidation of retinol (an alcohol)
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In the dark the chromophore is in the
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11-cis-retinal form
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When a photon of light is absorbed the retinal
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Undergoes cis/trans isomerization to become all-trans retinal
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The all trans retinal dissociates from the
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Opsin
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Light blocks the entry of
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Na into photoreceptor outer segment = hyperpolarization
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The Neurotransmitter b/t photoreceptors and bipolar and amacrine cells is
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Glutamate
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Horizontal and amacrine cells directly modify the
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Rate of electrical firing in bipolar cells
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The major excitatory transmitter for horizontal cells is
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Glutamate
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In inhibitor of horizontal and amacrine cells is
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GABA
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The major excitatory transmitter for amacrine cells is
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AcH
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An inhibitor of amacrine cells is
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Glycine
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In the dark
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Neurotransmitters are constantly released
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In the light
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The amount of NT released decreases
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Horizontal cell receptor fields result in a
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Larger, slower hyperpolarization that photoreceptors do
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The amacrine cell gives a
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Short, transient or phasic depolarization with a change in light level over a wide receptive field
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The principle of univarience refers to the fact that
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No matter how much above threshold the wavelength of light hits the photoreceptor…it will produce the same exact response
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Blue cones have a peak density
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1o from the fovea
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Parvocellular cell layers of the LGN (3,4,5 and 6) relay
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Ganglion cells to the visual cortex
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Magnocellular cell layers of the LGN (1 and 2) relay
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From the primary visual cortex to the secondary visual cortex and on to the MT and MST region
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Contralateral (crossed) ganglion cell axons end up in
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Layers 1,4,6 of the LGN
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Ipsilateral (uncrossed) ganglion cell axons end up in
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Layers 2,3,5 of the LGN
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Simple cells of the LGN have
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Elongated center surround receptors that respond to extended stimuli – stimulus must have the proper orientation
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The response of Special simple cells depends on
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The length of the stimulus
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Complex cells require the correct
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Orientation and size stimulus
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As long as the orientation is correct, a stimulus
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Anywhere in the receptive field of a complex cell will cause a response
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The primary input to the cortex form the LGN goes to
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Layer 4
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Collaterals of both the magno and parvo cells terminate
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In layer 6 of the cortex
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Intralaminar cells terminate in
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Layers 2 and 3
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Spiny stellate can pyramidal cortex cells are
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Excitatory
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Smooth stellate cells are
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Inhibitory
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Pyramidal cells have
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Long, large axons and spiny type processes
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Stellate cells have
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Short axons and either smooth or spiny processes
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Ocular dominance is the
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Classification of the binocularity of a particular cell
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Group 1 cells
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Stimulated only by contralateral eye
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Group 2 and 3 cells
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Codominant – more by contralateral eye
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Group 4 cells
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Equal binocular response
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Group 5 and 6 cells
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Codominance – more by ipsilateral eye
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Group 7 cells
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Only to ipsilateral eye
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Chromophore of rods and cones
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11-cis-retinal (light catching molecule)
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Light causes the 11-cis-retinal to changes to
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All-trans-retinal through photoisomerization
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The all trans form dissociates from the
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Opsin and is released into the cytosol
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The all-trans-retinal is converted back to 11-cis-retinal
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By retinal isomerases in the cytosol
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The all-trans-retinal activates the
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G protein, transducin which activates a G protein cascade
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The G protein cascade results in a
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Decrease in cGMP concentration in the cytosol
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cGMP is then released from its binding site on
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Sodium channels – causes Na+ channels to close
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The closing of the Na+ channels causes a
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Hyperpolarization of the membrane
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Hyperpolarization leads to the
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Transmission of the nerve pulse
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In the dark the outer segment of the photoreceptor is
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Highly permeable to Na+
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