eye review

Question 1

what are the refractive errors and how to we treat them

Answer 1

impaired vision that be fixed with corrective lens.

Question 2

hyperopia

Answer 2

eye too short for the refractive power of the cornea and lens. light focused behind the retina.

Question 3

myopia

Answer 3

eye too long for the refractive power of the cornea and lens. light focused in front of the retina.

Question 4

astigmatism

Answer 4

abnormal curvature of the cornea resulting in different refractory indexes at different axes. \

Question 5

accommodation

Answer 5

focusing on nearby objects. colliery muscle tightens. zonular fibers relax and the lens becomes more convex. occurs with convergence and mitosis.

Question 6

presbyopia

Answer 6

decreased change in the focusing ability during accommodation due to sclerosis and decreased elasticity. this happens with aging.

Question 7

Uvietis

Answer 7

inflammation of the Uveal coat and is often associated with systemic inflammatory disorders. sarcoid, rheumatoid, juvenile idiopathic arthritis, TB, HLA-B27 associated conditions.

Question 8

retinitis

Answer 8

retinal edema and necrosis leading to scar. often associated with viruses like HSV, CMV, HZV.

Question 9

open/wide angle glaucoma

Answer 9

characterized by peripheral then central vision loss usually with increased IOP; optic disc atrophy with cupping.

Question 10

what is open/wide angle glaucoma associated with?

Answer 10

older age, African American, family history, increased intraociular pressure.

Question 11

what the primary and secondary causes of open/wide angle glaucoma

Answer 11

primary = unsure.
secondary: Uveitis, trauma, corticosteroids, vasoproliferative retinopathy that can block the outflow at the trabecular meshwork.

Question 12

closed/narrow angle gluacoma

Answer 12

enlargement or forward movement of lens against the central iris leads to obstruction of the normal aqueous flow through pupil. fluid builds up behind the iris. this pushes the peripheral iris toward the cornea and this impedes the flow of aqueous through the trabecular meshwork. this is often asymptomatic

Question 13

acute closure of the angle

Answer 13

pain! emergency. sudden vision loss, halos around lights, rock hard eye, frontal headache.

Question 14

what do you not give in acute angle glaucoma

Answer 14

epinephrine –mydriatic effect.

Question 15

what are the risk factors for cataracts

Answer 15

smoking, age, EtOH, excessive sunlight, corticosteroids, trauma, infection, diabetes (sorbitol), classic galatosemia, galactokinase deficiency.

Question 16

what does CN VI innervate

Answer 16

lateral rectus.

Question 17

what does CN IV innervate

Answer 17

superior oblique

Question 18

what does CN III innervate

Answer 18

innervates the rest of the oculomotor units

Question 19

what happens with CN III damage

Answer 19

down and out eye. ptosis, pupillary dilation, loss of accommodation

Question 20

what happens with CN IV damage

Answer 20

eyes move upward, particularly with contralateral gaze and ipsilateral head tilt (problems going down stairs).

Question 21

what happens with CN VI damage

Answer 21

medially directed eye that cannot abduct.

Question 22

what causes miosis of the pupil

Answer 22

constriction of the pupil is caused by parasympathetics. 1) edinger-westfall nucleus (CN III), to ciliary ganglion
2) short colliery nerves to pupillary sphincter muscles.

Question 23

what causes mydriasis

Answer 23

dilation is caused by sympathetics. 1) hypothalamus to ciliospinal center of budge (C8-T12). 2) exit at T1 to superior cervical ganglion, which travels along the cervical sympathetic chain near the lung apex and subclavian vessels. 3) plexus along the internal carotid, through the cavernous sinus; enters the orbit as long cilliary nerve to pupillary dilator muscles.

Question 24

How the pupillary light reflex works

Answer 24

light enters the retina sends signals via CN II to pretectal nuclei in midbrain that activates bilateral Edinger-Westfall nuclei and the pupils contract bilaterally.

Question 25

Marcus-Gunn pupil

Answer 25

afferent pupillary defect due to optic nerve defect of detached retina. there is decreased bilateral pupillary constriction when light is shone in affected eye relative to the unaffected eye.

Question 26

what are the signs of motor deficit in CN III. common causes

Answer 26

ptosis and down and out gaze.

mainly affected by vascular disease, such as diabetes

Question 27

what is the medial longitudinal fasciculus and what does it do

Answer 27

the MLF is a pair of tracts that allows for crosstalk between CN VI and CNIII nuclei. it coordinates both eyes to move in horizontal direction.

Question 28

why and how is MLF associated with multiple sclerosis

Answer 28

the MLF is highly myelinated and is affected in MS. one of the features of MS if internuclear ophthalmoplegia.

Question 29

is convergence affected in demyelinating syndromes that affect the MLF?

Answer 29

No. convergence is usually preserved.

Question 30

internuclear ophthalmoplegia

Answer 30

it is a disorder of lateral gaze in which the affected eye has a defect in adduction. when this happens the unaffected eye is looking outward and has lateral nystagmus.
If there is a right sided INO, then when looking left and when the left eye abducts it will have nystagmus. the right eye will not move from midline.