COA exam study Questions and Answers

COA exam study Questions and Answers (JCAHPO) levator palpebrae superioris - answer Muscle that elevates the lid Sclera - answer white opaque fibrous shell, main purpose is to protect eye Cornea - answer A transparent convex covering which protects the eye and helps focus light rays onto the retina and the back of the eye meibomian glands - answer The largest oil-secreting glands, which are embedded in the posterior connective tissue substance of the lids Corneal Epithelium - answer 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. Corneal Epithelium - answer Part of the cornea that regenerates rapidly and heals without leaving a scar. Bowman's membrane - answer Consists of randomly oriented collagen fibrils of greater periodicity then the underlaying stroma. Bowman's membrane - answer Acellular layer of cornea that has no regenerative capabilities. Function is unclear. Stroma - answer Layer just under Bowman's membrane. Accounts for 90% of corneal thickness and is composed of 78% water. Descemet's membrane - answer Layer of the cornea that is composed of type III collagen, forms the basement membrane of epithelial cells. Endothelium - answer 4-6um thick layer of the cornea made of 500,000 cells that maintains corneal deturgescence. No regenerative abilities. Limbus - answer The gray, semitransparent area which demarcates the junction of the cornea and sclera. Cornea is completely nourished by - answer 3 sources: A plexus of fine capillaries at the limbus, the tear film, and the aqueous humor. Vitreous - answer jelly like structure, thick and viscous, that occupies the vitreous chamber in the posterior concavity of the globe. Lens - answer A transparent biconvex structure situated between the iris and the vitreous. Iris - answer The most anterior structure of the uveal tract. Uveal tract - answer Consists of three structures: iris, ciliary body, and choroid. Retina - answer The innermost coat of the eye, formed of sensitive nerve elements and connected to the optic nerve. A-scan - answer An ultrasound technique to determine the axial length of the eye to calculate the intraocular lens power required. Abbe number - answer An indication of optical quality. Number is inversely proportional to the chromic dispersion of a specific lens material Abduct - answer to turn away from the midline Abductor - answer A muscle that rotates the eye away from the midline (e.g. lateral rectus) Aberrant - answer Turning away from the midline Ablation - answer The removal of tissue as occurs with the excimer laser on the cornea for refractive changes.