Home > Flashcards > Physiology > Ocular Physiology Test 1

Details Title: Ocular Physiology Test 1 Description: Iris and Pupil Total Flash Cards: 43 Created: 09/24/2007 19:57:25	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term What are four functions of the pupil? Definition Control illuminance Participate in depth of focus (miosis with accomodation) Pinhole effect Decrease spherical abberation Term When does the pupil develop embryologically? Definition About 7 months gestation Term The development of the pupil results from the atrophy of what? Definition Iris tissue Resulting from cessation of circulation centrally Term When the atrophy of the iris tissue is not fully complete what happens? Does it cause harm? Definition Get persistent pupillary membranes Causes no harm to the patient VA wise (like multiple pinholes) Term What two cell types are found in the iris stroma? What else is found here? Definition Melanocytes and fibroblasts Collagen, vessels, and nerves are also present Term The distribution of these cells in the iris is what gives your eye its color Definition Melanocytes Term The anterior epithelium of the iris contains what two important muscles? Definition Dilator and sphincter Term Is the posterior epithelium of the iris pigmented? Is this where your eye color comes from? Definition YES NO Term The vascular network of the iris and pupil is made of what? Definition Minor circle, major arterial circle in CB near iris root, and radial vessels Term The vascular network of the iris and pupil must meander/slack to allow flexibiliy. Why? Definition Because the iris is constantly changing shape Term In order to prevent leakage of the vascular network of the iris and pupil what type of junctions are found? Definition Tight endothelial junctions Term The color of the eye is determined by the amount of ________ and hemoglobin of vessels. Definition Melanin Term Is heterochromia congenital or acquired? Definition Can be both Congenital - benign Acquired - pathologic Term What are some of the acquired causes of heterochromia? Definition Horner's syndrome, melanoma, drug induced change in melanin, vascular change, chronic uveitis (Fuch's heterochromic iritis) Term The circular fibers of the pupil _____ and the radiating fibers of the pupil ________. Definition Constrict Dilate Term Is the sphincter muscle at the pupillary margin? Definition YES Term What is the innervation pathway of the sphincter muscle? Definition EW nucleus - ciliary ganglion synapse - short posterior ciliary nerve - sphincter Term Do the near and light response of the sphincter share the same pathway? Definition YES Term Does the sphincter muscle contain nicotinic or muscarinic receptors? Definition Muscarinic (cholinergic) Term Is the dilator muscle present at the pupillary margin? Definition NO - Radial Term What is the innervation pathway of the dilator muscle? Definition Superior cervical ganglion in neck - sympathetic plexus at carotid - sympathetic root passes through ciliary ganglion - short posterior ciliary nerve - dilator muscle Term Does the dilator have alpha or beta adrenergic receptors? Definition Alpha Sphincter has Beta Term The tonic state of the iris is determined by what? Definition Balance of cholinergic/adrenergic receptors Term There are __ ways to dilate and __ ways to constrict. Definition 2 and 2 Relax radial and constrict circular - Constrict Contract radial and relax circular - Dilate Term What is hippus? Is absence of this a problem? Definition Bouncing of pupil margin Yes - innervation problem if not present Term What is the function of the mitotic light response? Definition Protective Reduces glare and reduces the bleaching of photorecpetors Term As light intensity increases, the contraction amplitude _____ , the latency for constriction _____ , and the time to return to normal ______ . Definition Increases Decreases Increases Term When you are dark-adapted do you have a lower or higher threshold to elicit contraction? Is your peripheral or central retina sensitivity higher? Definition Lower Peripheral Term Pupil escape occurs when light hits the eye, the pupil contracts and then it bounces back out just a little bit. Most young clinicians confuse this normal response with what? Definition A positive afferent pupillary defect (APD) Term What are the afferent and efferent pupillary pathways of the pupil? Definition Afferent - retinal ganglion fiber to ipsilateral pretectal nucleus for nasal and contralateral for temporal to fibers to ipsilateral and contralateral EW nucleus Efferent - EW to sphincter muscle Term The two pupils responses should be symmetric and what? Definition Of equal size Term The pupils should have a direct and consensual response to light and what? Definition Near objects Term If the pupil response to near targets is larger than its response to light, is this a problem? Definition YES Term The Marcus-Gunn test looks for what? Definition Relative afferent pupil defects Term The presence of an APD is usually graded on a scale of what to what? How else can you quantify the severity of the APD? Definition 1+ to 4+ - Based on clinical judgement Can also quantify with ND filter over normal eye Term Is miosis dependent on accomodation or convergence? Definition NO - It is a "co-movement" elicited together with accomodation and convergence Term The centrally integrated near triad is elicited together by the forebrain during the ______ act of near vision. Definition Voluntary Cognitive input is important Term What are two stiumli to accomodation? Do they require cognitive input? Definition Retinal blur and proximal awareness YES Term The miotic near response functions to do what? Definition Increase depth of focus and slacken "precision of focus" requirements and to reduce spherical abberation Term The convergence needed for the near response is under the motor control of what nuclei? accomodation? miosis? Definition Oculomotor subnuclei for MR Anteromedial portion of occulomotor nucleus Small celled columns in EW area of occulomotor group Term Nucleus of Perlia? Definition Possible cell location for convergence Term The AC/A ratio is linear over a range of accomodation responses. Does it change with age? Can it be altered by other means? Definition YES YES - Problem with accomodation or convergence can alter the ratio Term The P/CA ratio is linear over a range of convergence. Do miosis and convergence continue after accomodation limits have been reached? Definition YES - they are not linked