first aid eye section

Question 1

hyperopia (farsightedness)

Answer 1

-eye too short for refractive power of cornea and lens–> light focused behind retina

Question 2

myopia (nearsightedness)

Answer 2

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

Question 3

presbyopia

Answer 3

decrease in focusing ability during accomodation due to scleoris and decreased elasticity

Question 4

Aqueous humor pathway

Answer 4

ciliary epithelium produce aqoeus humor (Beta)–> travels to anterior chamber–> the trabecular meshwork collects the aqueous humor–> the canal of schlemm collects the humor from the trabecullar meshwork

Question 5

glaucoma

Answer 5

• optic disk atrophy with characteristic cupping
• increased intraocular pressure IOP
• progressive peripheral visual field loss

Question 6

cataract

Answer 6

• painless, often bilateral, opacification of lens
• decrease in vision
• risk factors: increased age, smoking, EtOH, excessive sunlight, prolong corticosteroid use, classic galactosemia, galactokinase deficiency, diabetes (sorbitol), trauma and infection

Question 7

Open angle glaucoma

Answer 7

assoc: increase age, black, fx 
painless
primary cause unclear
secondary: blocked trabecular meshwork from WBC (uveitis), RBC (vitreous hemorrahage), retinal elements (retinal detachement)
--> increased intraocularpressure

Question 8

closed/narrow angle glaucoma

Answer 8

primary:
enlargement or forward movement of the lens against the iris leads to obstruction of the normal aqous flow through pupil–> fluid back up behind the iris–> pushing the peripheral iris agianst the cornea and impeding flow through the trabecular network.

secondary:
hypoxia from retinal disease (diabetes, occlusion) induces vasoproliferation in the irsis that contracts the angle

Question 9

chronic closed/narrow angle glaucoma

Answer 9

Chronic: often aysmptomatic with damage to optic nerve and peripheral vision

Question 10

acute closed/narrow angle glaucoma

Answer 10

acute: EMERGENCY increased IOP pushes the iris forward and the angle closes ABRUPTLY. very painful, sudden vision loss, halos around lights, rock hard eye, frontal headache. DO NOT give epi because of its mydriatic effect

Question 11

CN III damage

Answer 11

eye looks down and out, ptosis, pupillary dilation (loss of parasympathetic), loss of accomodation

Question 12

CN VI abducens lesion

Answer 12

medially directed eye that cannot abduct

Question 13

CN IV trochlear lesion

Answer 13

superior oblique (normall moves eye down and out)
eye moves upward, particulalty with contralateral gaze .

Question 14

Miosis (constriction, parasympathetic)

Answer 14

1st neuron edinger westphall nucleus to ciliary ganglion via CN III
2nd neuron: short ciliary nerves to pupillary sphincter muscles

Question 15

Mydriasis (dilation, sympathetic)

Answer 15

1st neuron: hypothalamus to ciliospinal center of budge (C8-T2)

2nd neuron: exit T1 to superior cervical ganglion (travels talong cervical chain sympathetic chain near lung apex and sublcavian vessels)

3rd neuron: plexus along internal carotid, though cavernous sinus and enters orbit as long ciliary nerve to pupillary dilator muscles—- interupt this chain and you can get horners syndrome

Question 16

pupillary light reflex

Answer 16

afferent: CN II to retectal nuclei in midbrain that activate bilateral edinger westphal nuclei –> CN III efferent –> pupil contract bilateally consensual reflex

Question 17

what can cause compression of parasympathetic output fibers of CN III?

Answer 17

Pcomm artery aneurism, uncal herniation

Question 18

lesion at optic nerve before chiasm

Answer 18

one eye anopia

Question 19

lesion at optic chiasm

Answer 19

bitermporal hemianopia

Question 20

lesion at optic tract

Answer 20

homonymous hemianopia all left or all right

Question 21

lesion in meyer loop (temporal lobe) inferior retina; loops around inferior horn of lateral ventricle

Answer 21

left or right UPPER quandrantic anopia

Question 22

Lesion in dorsal optic radiation - superiror retina ,takes shortest path via internal campsues –> parietal lesion, MCA

Answer 22

LOWER quandrantic anopia

Question 23

PCA infarct

Answer 23

hemianopia with macular sparing

Question 24

central scotoma

Answer 24

macular degerenation

Question 25

Medial longitudinal fasiculus MLF

Answer 25

Cross talk between CN VI and CN III
When looking left, the left nucleus of CN Vi fires, which contracts the left lateral rectus muscle and stimulates the contralateral right nucleus of CN II via the right MLF to contract the medial rectus.

Question 26

Internuclear opthalmoplegia INO

Answer 26

Lesions of demyelination of the MLF
-MS

So the CN Vi fires, but it cant communicated with CN III via MLF, and the CN VI overfires to stimulated CN III and it gets abduction with nystagmus.