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Outer Tunic of eye
Fibrous |
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Inner Tunic of Eye
Neural |
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Middle Tunic of Eye
Vascular AKA Uvea
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| Iris, Ciliary Body, Choroid |
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| Transitional region between the cornea/sclera |
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| transparent and allows light to enter the globe |
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| Structure that regulates the amt of light entering the pupil |
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Structure that produces aqueous humor and contains the muscle that controls the lens |
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| Contains network of blood vessels that supplies the outer retinal layers |
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| This processes light and transmits visual info the the rest of the brain through the optic nerve |
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| Bounded by the cornea anteriorly and the iris/front of lens posteriorly. Contains aqueous humer |
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| Lies behind the iris and surrounds the equator of the lens--the Contains aqueous humor |
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| provides nourishment to the lens/cornea and surrounding structures (where there is no blood supply) |
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| structure located in posterior chamber and provides refractive power--(and adjustable ref. power) |
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| region that represents a change in pattern and characteristics of the collagen and cells that make up the outer fibrous layer |
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| Main channel that collects the aqueous humor--located at the limbus |
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| muscles that insert into the scleral covering of eye |
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| portion of sclera that continues across optic nerve and forms perforated layer through which the optic nerve fibers pass on the way to the brain |
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| gel like substance in vitreous body--there for life(not replaced) |
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| structure that is reflexively enlarged or reduced by the iris dilator and sphincter muscles |
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Zonular Fibers
aka ciliary fibers |
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| what runs between the equator of the lens and the inner surface of the ciliary body |
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This begins at the optic nerve posteriorly and extends to the ora serrata anteriorly.
Also provides nutrition to the photoreceptor layer of the retina. |
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| this externds anteriorly from the the optic nerve and ends at the ora serrata |
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junction between ciliary body and the retina
Nerve cells of the retina stop here |
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| region of the retina that contains the fovea and foveola |
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| Part of fovea that contains highest density of cones |
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| this bounds the posterior of the posterior chamber. Also forms a depression which confrims to the posterior surface of the lens |
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| Know the Flow of Aqueous Humor |
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| away from the point of origin |
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| vertical plane--divides left and right |
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| vertical plane--divides front and back |
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| horizontal plane--divides into superior and inferior (top/bottom) |
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| light correctly focused on the retina |
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distance from cornea to retina is too short
focal point behind retina |
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distance from cornea to retina is too far
focal pt is in front of retina |
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| instrument that measures the curvature of the central cornea |
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| instrument that measures accomodative function and optical power of the eye with a set of lenses |
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slit-lamp
aka biomicroscope |
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| used to image the eyelids and outside of globe. Good to view transparent structures (cornea/lens) |
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| instrument used to test the extent, sensitivity, and completeness of one's visual field |
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| formed by epithelial cells--attaches epi cells to connective tissue |
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| part of basement membrane secreted by epi cells |
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| part of basement membrane that is a product of connective tissue layer |
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| several layers of epi cells |
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| tougher than regular epi. Protects against dehydration, bacteria, and injury |
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| epithelium with apical squamous cells, basal cuboidal or columnar--function:Protection |
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| more than1 layer of cuboidal cells Function:secretion/absorption |
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Single layer columnar then several cuboidal layers
Function:protection/secretion |
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cell types vary and are often multi-nucleated--
Function: distention (Bladder, ureter, etc) |
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| secrete directly into the blood |
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| secrete part of the cell cytoplasm |
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| secrete product that has no part of cell |
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| junctions that are tight--nearly impermeable to fluids |
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| junctions that are intermediate |
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| Strong spot like attachements between cells |
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| communicating junctions that allow cytoplasm to pass between cells. (direct communication between cells) |
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| tissue in which fibers are elongated, cells are slender,have 1 central nucleus |
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| tissue that has regular pattern of light and dark bands |
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| specialized cells that react to stimulus and conduct nerve impulses |
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| cells that provide structural and metabolic support in nerve tissue |
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| receives the message in neuronal communication |
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| transmits the message in neuronal communication |
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| insulation that improves conduction speed of neurons |
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| cells that produce myelin the the PNS |
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| Specialized junction where impulses are transmitted from 1 neuron to the next |
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| ratio of neuroglial cells to neurons |
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| neuroglial cells that provide structure and nutrition |
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| Neuroglial cells that produce myelin in the CNS |
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| Neuroglial cells that possess phagocytic properties. Increase in areas of damage or disease |
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| this condition results from unequal refraction of light by different meridians of the refracting elements |
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| Astig. where longest and shortest radius of curvature are 90 degrees apart |
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| Astig. where meridians corresponding to the greatest difference are not 90 degrees apart |
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| Astigmatism where the vertical medirian has the steepest/shortest radius of curvature. Football on its side |
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| Astigmatism where the horizontal meridian is steepest. football standing up on tip |
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| Astigmatism where greatest differences are not at 90 & 180(+ - 30), but at 45&135 degrees(+-15) |
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| 5-7 layers of cells (50microns) |
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| thickness of Corneal Epithelium |
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| Thickness of Bowmans layer of Cornea |
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| Flat bundles of collagen fibrils in stroma that run parallel to one another across whole cornea from limbus to limbus. (they do have a random pattern see slide 12 of cornea lecture) |
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| 500 microns-- 90% of total thickness |
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Definition
| thickness of corneal stroma |
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Definition
corneal dystrophy--starts with focal disruptions of basement membrane and bowman's layer.
Stroma thins, and unaffected area projects outward in a cone shape b/c of IOP. |
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| thickness of corneal endothelium |
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Definition
This layer of the cornea governs fluid and solute transport across posterior of cornea from the aq. humor. (Maintains slight dehydrated state of cornea)
Cells here are also 6,7 sided |
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| Corneal Endothelium cells |
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Definition
| Cells that have the 2nd highest metabolic rate behind the photoreceptors (have lots of Mitochondria) |
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| the regular arrangement of corneal endothelial cells |
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| Increase or loss in variability of corneal endothelium cell shape |
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| Increase or decrease in cell size of corneal epithelium cells |
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Hassall Henle (in periphery of cornea)
or
Guttata (in center of cornea) |
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Deposits/mounds of basement membrane material created by the corneal endothelium. The mounds have thinned endothelium so barrier is compromised. Shows up as periodic thickenings in Descemet's membrane.
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| epithelial thinning, stromal thinning, decrease in keratocytes, pleomorphism and polymegathism--all of these can be a result of : |
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| finger-like projections on the corneal epithelium increase surface area(enhance tear film stability) |
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| ridge-like projections on the corneal epithelium increase surface area(enhance tear film stability) |
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| zonula occludens (tight junctions) |
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Definition
| Type of junctions on the apical surface of the cornea. |
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Term
surface cells:2 nonkeritinzed squamous cells
wing cells: middle layer (2-3) cells
basal cell: 1 layer pf columnar cells--(mitosis occurs here)
(WHOLE EPITHELIUM REPLACED ~weekly)
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| cell make up of corneal epithelium |
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| RCE Recurrent Corneal Erosions |
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Definition
This occurs as a result of damage to basal cell layer of corneal epithelium and can take months to heal (whereas damage to surface heals in hours).
Also classifed by failure of basal cells to attach to bowman's layer and exposed corneal nerves so painful condition. |
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Definition
| layer of the cornea that is a dense, fibrous sheet of interwoven collagen fibrils randomly arranged and is transitional to the stroma. It's only function: to resist damage. |
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| Cells that maintain corneal stroma by synthesizing collagen and extracellular matrix components. They are arranged in a corkscrew pattern and are flattened cells that lie between lamellae |
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| white blood cells, lymphocytes, leukocytes, and white blood cells--these increase in pathologic conditions and affect transparency. |
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Definition
| Cells that are inbetween lamellae other than Keratocytes |
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| the scatter is minimal and separated by small distances (less than 1% scattered) |
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Definition
| Why is scattering in the cornea minimal if the epithelium, bowman's and descemets layers are irregularly arranged? |
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| This is considered the basement membrane of the corneal endothelium. It also is constantly growing through life--doubles in size by age 40 |
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| thickened area of collagenous connective tissue at the descemets termination in the limbus |
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| innermost layer of the cornea that is adjacent to the anterior chamber |
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Cornea 43-48D
Lens 15-18 D |
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| The cornea and lens each account for how many diopters of the eye's total refractive power? |
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| benign growth on cornea due to UV exposure |
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Photokeratitis
aka arc eye (welding) pr snowblindness(snow, sand, water) |
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| painful condition as a result of acute UV exposure |
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| damage to cornea epi or endo can result in this. An increase in fluid retention occurs and the posterior stroma and descemet's buckle forming vertical lines called striae |
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| REVIEW SLIDE 23 in Cornea lecture--know if/how each layer of cornea is replaced after injury |
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| Corneal Neovascularization |
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| this is the excessive growth of blood vessels from the limbal vascular plexus into the cornea--due to low oxygen reception. Can be stopped, but empty vessels remain as ghost vessels. |
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| Descemets and Endothelium |
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Definition
| Which layers of the cornea have no nerve endings? |
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Long and short ciliary nerves go into the stroma, and then branch into mid-stroma, subepithlium and epithelium.
Also has sympathetic nerve fibers for metabolism, prolieferation and wound healing. |
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| Innervation of the cornea |
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| These are the termination of nerve endings in corneal epithelium--make corneal abrasions painful |
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| this maintains the shape of the globe, offers resistance to internal and external forces, and is where the extraocular muscles attach |
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| .33mm at the posterior and about 1 mm by the time it gets to the anterior |
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Definition
| Sclera thickness distribution |
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| Myopic eye generally larger the emmetropic eye--thinning of sclera may be a factor when emmetopia doesn't occur |
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| Sclera and Myopic development |
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| this is the origin of longitudinal ciliary muscle fibers posteriorly. Anteriorly it is continuous with the trabecular meshwork. It's a region of circularly oriented collagen bundles that extends from the inner aspect of the sclera |
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this is when the thin root of of iris tears away from the ciliary body as a result of blunt trauma--can result in damaged blood vessels and nerves.
Blood can also leak into either ant. or post. chambers and cause nerve damage that may paralize iris muscles |
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blue:in newborns or peoole with connective tissue disease.
Yellow: b/c of fatty deposits. Can happen with age and liver disease.
White: healthy sclera |
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| Scleral colors-blue vs white vs yellow |
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| where is the anterior scleral foramen? |
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| where the optic nerve passes through. |
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| where is the posterior scleral foramen? |
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| the optic nerve--so can foreshadow for disease processes |
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| where is the weakest area in the outer tunic? |
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| ectasia or cupping out of the center area of the surface of the optic nerve. May be evident in pts with increased IOPs |
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| these pass through the sclera and carry nerves and vessels. They're also possible routes for disease to exit or enter the eye |
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| the canals of the sclera that lie 4mm posterior to the equator and carry the vortex veins |
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| these canals are located around posterior scleral foramen(where optic nerve is)--passages for posterior ciliary arteries and nerves |
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| these canals are near the limbus at the muscle insertions. They're passages for anterior ciliary vessels which are branches from the muscular arteries |
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| the sclera is avascular, gets nourishment from episcleral and choroidal vessels, along with long posterior ciliary arteries. |
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posterior--innervated by short ciliary nerves
rest of sclera--by long ciliary nerve branches |
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| the radius of curvature changes at this part of the corneoscleral junction, creating a shallow, narrow furrow. |
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| these are radial projections of the limbal epithelium and stroma and extend into the cornea in spike like fashion. |
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| method of contact lens fitting to change the shape of the cornea to correct refractive error |
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| iron deposits in corneal epithelial cell cytoplasm, more concentrated in the basal cells. Can ususally see this at the lower lid margin. Normal w/age |
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| most common corneal aging change-circular yellow-white deposit in the peripheral stroma |
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| yellowish white opacity caused by of the bowmans layer of the cornea at 3 and 9 o'clock--normal w/age |
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| pigment deposits on the posterior cornea that have vertical orientation |
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the posterior iris surface is adherent to the anterior lens surface
If involves a large part of the iris aq. humor will build up in post. chamber. This causes the iris to bow forward into an Iris Bombe |
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| surgically removing a wedge of the iris so that aqueous humor can flow between the ant and post chambers |
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| Poking a hole in the iris(usually with a laser) to allow aqueous humor to flow between ant. and post. chambers |
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| this is located at the limbus and is contains trab. meshwork and schlemm's canal where aq.humor drains |
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anterior synechia
aka PAS peripheral anterior synechia |
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Definition
the anterior iris surface is adherent to the trabecular meshwork.
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| pieces of iris pigment break off posterior iris and may compromise aq. humor flow. |
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| a person's irises are differnet color, or a portion of the iris is different from the rest. |
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