COA exam study (JCAHPO) – Flashcards
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levator palpebrae superioris
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Muscle that elevates the lid
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Sclera
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white opaque fibrous shell, main purpose is to protect eye
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Cornea
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A transparent convex covering which protects the eye and helps focus light rays onto the retina and the back of the eye
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meibomian glands
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The largest oil-secreting glands, which are embedded in the posterior connective tissue substance of the lids
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Corneal Epithelium
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Part of the cornea that is usually injured by superficial abrasions or small foreign bodies. Is 5-7 cells thick and is composed of nonkeratinized stratified squamous cells.
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Corneal Epithelium
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Part of the cornea that regenerates rapidly and heals without leaving a scar.
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Bowman's membrane
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Consists of randomly oriented collagen fibrils of greater periodicity then the underlaying stroma.
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Bowman's membrane
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Acellular layer of cornea that has no regenerative capabilities. Function is unclear.
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Stroma
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Layer just under Bowman's membrane. Accounts for 90% of corneal thickness and is composed of 78% water.
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Descemet's membrane
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Layer of the cornea that is composed of type III collagen, forms the basement membrane of epithelial cells.
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Endothelium
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4-6um thick layer of the cornea made of 500,000 cells that maintains corneal deturgescence. No regenerative abilities.
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Limbus
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The gray, semitransparent area which demarcates the junction of the cornea and sclera.
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Cornea is completely nourished by
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3 sources: A plexus of fine capillaries at the limbus, the tear film, and the aqueous humor.
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Vitreous
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jelly like structure, thick and viscous, that occupies the vitreous chamber in the posterior concavity of the globe.
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Lens
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A transparent biconvex structure situated between the iris and the vitreous.
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Iris
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The most anterior structure of the uveal tract.
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Uveal tract
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Consists of three structures: iris, ciliary body, and choroid.
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Retina
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The innermost coat of the eye, formed of sensitive nerve elements and connected to the optic nerve.
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A-scan
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An ultrasound technique to determine the axial length of the eye to calculate the intraocular lens power required.
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Abbe number
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An indication of optical quality. Number is inversely proportional to the chromic dispersion of a specific lens material
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Abduct
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to turn away from the midline
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Abductor
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A muscle that rotates the eye away from the midline (e.g. lateral rectus)
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Aberrant
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Turning away from the midline
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Ablation
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The removal of tissue as occurs with the excimer laser on the cornea for refractive changes.
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Abrasion
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Rubbing off of the superficial layer
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Abcess
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Localized area of inflammation
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AC/A
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Accommodative convergence/accommodation ration; expressed as the ratio between convergence caused by accommodation (in prism diopters) and accommodation (in diopters).
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Accommodation
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Adjustment by the eye for seeing at different distances, accomplished by changing the shape of the crystalline lens through the action of the ciliary muscle.
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Achloropsia
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Color blindness to green
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Achromatic lens
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A lens that neutralizes dispersion without interfering with refraction.
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Acuity
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Clearness; visual acuity is measured by the smallest object that can be seen at a certain distance.
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Add
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The total dioptric power added to a distance prescription to supplement accommodation for reading.
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Adductor
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A muscle that exerts force towards the midline.
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Adie's pupil
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A tonic pupil with sluggish response to lights, accommodation, and convergence.
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Adnexa oculi
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Accessory structures of the eye, such as the lacrimal apparatus and the eyelids.
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Alexia
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Inability to read words previously known even though visual perception is clear.
