Term
| What are four functions of the pupil? |
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Definition
Control illuminance
Participate in depth of focus (miosis with accomodation)
Pinhole effect
Decrease spherical abberation |
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Term
| When does the pupil develop embryologically? |
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Definition
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Term
| The development of the pupil results from the atrophy of what? |
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Definition
Iris tissue
Resulting from cessation of circulation centrally |
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Term
| When the atrophy of the iris tissue is not fully complete what happens? Does it cause harm? |
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Definition
Get persistent pupillary membranes
Causes no harm to the patient VA wise (like multiple pinholes) |
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Term
| What two cell types are found in the iris stroma? What else is found here? |
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Definition
Melanocytes and fibroblasts
Collagen, vessels, and nerves are also present |
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Term
| The distribution of these cells in the iris is what gives your eye its color |
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Definition
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Term
| The anterior epithelium of the iris contains what two important muscles? |
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Definition
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Term
| Is the posterior epithelium of the iris pigmented? Is this where your eye color comes from? |
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Definition
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Term
| The vascular network of the iris and pupil is made of what? |
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Definition
| Minor circle, major arterial circle in CB near iris root, and radial vessels |
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Term
| The vascular network of the iris and pupil must meander/slack to allow flexibiliy. Why? |
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Definition
| Because the iris is constantly changing shape |
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Term
| In order to prevent leakage of the vascular network of the iris and pupil what type of junctions are found? |
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Definition
| Tight endothelial junctions |
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Term
| The color of the eye is determined by the amount of ________ and hemoglobin of vessels. |
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Definition
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Term
| Is heterochromia congenital or acquired? |
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Definition
Can be both
Congenital - benign
Acquired - pathologic |
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Term
| What are some of the acquired causes of heterochromia? |
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Definition
| Horner's syndrome, melanoma, drug induced change in melanin, vascular change, chronic uveitis (Fuch's heterochromic iritis) |
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Term
| The circular fibers of the pupil _____ and the radiating fibers of the pupil ________. |
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Definition
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Term
| Is the sphincter muscle at the pupillary margin? |
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Definition
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Term
| What is the innervation pathway of the sphincter muscle? |
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Definition
| EW nucleus - ciliary ganglion synapse - short posterior ciliary nerve - sphincter |
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Term
| Do the near and light response of the sphincter share the same pathway? |
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Definition
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Term
| Does the sphincter muscle contain nicotinic or muscarinic receptors? |
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Definition
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Term
| Is the dilator muscle present at the pupillary margin? |
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Definition
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Term
| What is the innervation pathway of the dilator muscle? |
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Definition
| Superior cervical ganglion in neck - sympathetic plexus at carotid - sympathetic root passes through ciliary ganglion - short posterior ciliary nerve - dilator muscle |
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Term
| Does the dilator have alpha or beta adrenergic receptors? |
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Definition
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Term
| The tonic state of the iris is determined by what? |
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Definition
| Balance of cholinergic/adrenergic receptors |
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Term
| There are __ ways to dilate and __ ways to constrict. |
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Definition
2 and 2
Relax radial and constrict circular - Constrict
Contract radial and relax circular - Dilate |
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Term
| What is hippus? Is absence of this a problem? |
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Definition
Bouncing of pupil margin
Yes - innervation problem if not present |
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Term
| What is the function of the mitotic light response? |
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Definition
Protective
Reduces glare and reduces the bleaching of photorecpetors |
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Term
| As light intensity increases, the contraction amplitude _____ , the latency for constriction _____ , and the time to return to normal ______ . |
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Definition
Increases
Decreases
Increases |
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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? |
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Definition
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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? |
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Definition
| A positive afferent pupillary defect (APD) |
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Term
| What are the afferent and efferent pupillary pathways of the pupil? |
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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 |
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Term
| The two pupils responses should be symmetric and what? |
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Definition
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Term
| The pupils should have a direct and consensual response to light and what? |
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Definition
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Term
| If the pupil response to near targets is larger than its response to light, is this a problem? |
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Definition
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Term
| The Marcus-Gunn test looks for what? |
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Definition
| Relative afferent pupil defects |
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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? |
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Definition
1+ to 4+ - Based on clinical judgement
Can also quantify with ND filter over normal eye |
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Term
| Is miosis dependent on accomodation or convergence? |
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Definition
| NO - It is a "co-movement" elicited together with accomodation and convergence |
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Term
| The centrally integrated near triad is elicited together by the forebrain during the ______ act of near vision. |
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Definition
Voluntary
Cognitive input is important |
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Term
| What are two stiumli to accomodation? Do they require cognitive input? |
|
Definition
Retinal blur and proximal awareness
YES |
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Term
| The miotic near response functions to do what? |
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Definition
| Increase depth of focus and slacken "precision of focus" requirements and to reduce spherical abberation |
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Term
| The convergence needed for the near response is under the motor control of what nuclei? accomodation? miosis? |
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Definition
Oculomotor subnuclei for MR
Anteromedial portion of occulomotor nucleus
Small celled columns in EW area of occulomotor group |
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Term
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Definition
| Possible cell location for convergence |
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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? |
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Definition
YES
YES - Problem with accomodation or convergence can alter the ratio |
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Term
| The P/CA ratio is linear over a range of convergence. Do miosis and convergence continue after accomodation limits have been reached? |
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Definition
| YES - they are not linked |
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