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Flashcards in Ophtho 2 Deck (22)
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1

Papilledema

Optic disc swelling (usually b/l) due to high ICP (secondary to mass effect sometimes)

Enlarged blind spot and elevated optic disc with blurred margins seen on exam

2

Cataracts

Painless, often bilateral opacification of lens leading to reduced vision

Risk factors: Age, smoking, EtOH, excessive sunlight, prolonged steroid use, classic galactosemia, galactokinase deficiency, diabetes (sorbitol), trauma, infection

3

Glaucoma

Optic disc atrophy with characteristic cupping (thinning of outer rim of optic nerve head versus normal

Usually with high IOP and progressive peripheral visual field loss

4

Open angle glaucoma

Associated with age, being black, family history

Painless, more common in US

Primary - cause unclear

Secondary - blocked trabecular meshwork from WBCs (uveitis), RBCs (vitreous hemorrhage), retinal elements (retinal detachment)

5

Closed angle glaucoma

Primary - enlargement or forward movement of lens against central iris (pupil margin) leading to obstruction of normal aqueous flow through pupil. Fluid builds up behind iris, pushing peripheral iris against cornea and impeding flow through trabecular network.

Secondary - hypoxia from retinal disease (diabetes, vein occlusion) induces vasoproliferation in iris that contracts the angle

Chronic closure - often ASx with damage to optic nerve and peripheral vision

Acute - True emergency. Increased IOP pushes iris forward leading to angle closing abruptly. Very painful, red eye, sudden vision loss, halos around lights, rock hard eye, frontal headache. Do not give epinephrine bc of its mydriatic effect

6

Uveitis

Inflammation of uvea (iritis aka anterior uveitis, choroiditis aka posterior uveitis).

May have hypopyon (accumulation of pus in anterior chamber) or conjunctival redness. Associated with systemic inflammatory disorders (sarcoid, RA, juvenile idiopathic arthritis, HLA-B27 associated conditions)

7

Miosis

Constriction, parasympathetic

1st neuron - EW nucleus to ciliary ganglion via CN 3

2nd neuron - short ciliary nerves to pupillary sphincter muscles

8

Pupillary light reflex

Light in either retina sends a signal via CN 2 to pretectal nuclei in midbrain that activates bilateral EW nuclei. Pupils constrict bilaterally (consensual reflex)

Result - illumination of 1 eye results in bilateral pupillary constriction

9

Mydriasis

Dilation - sympathetic

1st neuron - hypothalamus to ciliospinal center of Budge (C8-T2). Synapse is in lateral horn.

2nd neuron - Exit at T1 to superior cervical ganglion (travels along cervical sympathetic chain near lung apex, subclavian vessels). Synapse is in superior cervical ganglion.

3rd neuron - plexus along internal carotid, through cavernous sinus. Enters orbit as long ciliary nerve to pupillary dilator muscles. Sympathetic fibers also innervate smooth muscle of eyelids (minor retractors) and sweat glands of forehead and face

10

marcus gunn pupil

APD - due to optic nerve damage or severe retinal injury.

Reduced bilateral pupillary constriction when light is shone in affected eye related to unaffected eye.

Test with swinging flashlight

11

Horner Syndrome

Sympathetic denervation of face

1) Ptosis - slight drooping of eyelid. superior tarsal muscle

2) Anhidrosis - absence of sweating and flushing of affected side of face

3) Miosis - pupil constriction

Associated with lesion of spinal cord above T1 (Pancoast tumor, Brown Sequard, late stage syringomyelia)

Any interruption results in Horner

12

EOMs

LR6SO4R3

13

How to test each EOM

Obliques go opposite. L SO and IO tested by looking R. IO tested looking up.

SO depression best tested when eye is adducted

SR - test by looking up and abducted

LR - test by abducting

MR - test by adducting

SO - look down and adduct

IO - look up and adduct

14

CN 3 damage

CN3 has both motor (central part of nerve) and parasympathetic (peripheral) components.

Motor output to ocular muscles is affected primarily by vascular disease (diabetes: glucose to sorbitol) due to lower diffusion of oxygen and nutrients to the interior fibers from compromised vasculature that resides on outside of nerve. Signs = ptosis, down and out gaze

Para output - fibers on periphery are affected first by compression (PCom aneurysm, uncal herniation). Signs = diminished pupillary light reflex, "blown pupil," often with down and out gaze

15

CN 4 damage

Eye moves upward, particularly with contralateral gaze and head tilt toward the side of the lesion (problems with going down stairs, may present with compensatory head tilt in the opposite direction

16

CN 6 damage

Medially directed eye that cannot abduct

17

INO

MLF: pair of tracts that allows for crosstalk btw CN 6 and CN 3 nuclei. Coordinates both eyes to move in same horizontal direction. Highly myelinated (must coordinate quickly). lesions may be unilateral or bilateral (bilateral seen in MS)

Lesion in MLF = INO. It's a conjugate gaze palsy. Convergence is spared (this is in midbrain whereas the MLF is in the pons)

The directional term refers to the eye that is paralyzed. Right INO (R MLF lesion) means right eye isn't moving.

Normal: When looking left, the L nucleus of CN 6 fires which contracts the L LR and stimulates contralateral (R) nucleus of CN 3 via R MLF to contract R MR.

The abducting eye in an INO will have nystagmus.

18

Latanoprost

1st line for glaucoma

Increases outflow through canal of schlem

Side effect: iris darkening

19

Cholinomimetics in treatment of glaucoma

Direct (pilocarpine, carbachol) and indirect (physostigmine and echothiophate). They all mimic effect of ACh or increase ACh.

Increase outflow via contraction of ciliary muscle and opening of meshwork.

use pilocarpine in emergencies!

Side effect: Miosis and cyclospasm (contraction of ciliary muscle)

20

Acetazolamide in treatment of glaucoma

Lowers aqueous humor synthesis via inhibition of carbonic anhydrase

21

B-blockers for glaucoma

Timolol, betaxolol, carteolol

Lowers aqueous humor synthesis

Timolol is most likely to have systemic side effects

22

A-agonists for glaucoma

Epinephrine (A1) and brimonidine (A2)

Lowers aqueous humor synthesis via vasoconstriction

Lowers aqueous humor synthesis directly

Side effects - mydriasis (A1) - do NOT use in close angle

Side effects - blurry vision, ocular hyperemia, foreign body sensation, ocular allergic reactions, ocular pruritis