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surgery > Ophthalmology > Flashcards

Ophthalmology Flashcards

1
Q

How does aqueous humor travel through the eye

A

o Aqueous humor is produced by ciliary process. Fluid passes from posterior to anterior via the pupillary aperture
o Travels through Schlemm’s canal
o Drains into the episcleral vein

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2
Q

What is the difference between closed and open angle glaucoma?

A

o Closed Angle Glaucoma:
- Caused when the anterior chamber angle is narrowed →reducing outflow of AH
- Occurs in people with small and shallow anterior chambers
o Open Angle Glaucoma:
- Increased resistance to aqueous humor outflow through trabecular meshwork
- Most common cause of blindness in NA à starts as visual field loss

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3
Q

What is secondary angle closure glaucoma?

A 
- Acute glaucoma secondary to 
	o Synechia
	o Lens dislocation
	o Intraocular tumours
	o Central Retinal Vein Occlusion
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4
Q

What factors can precipitate an episode of acute angle glaucoma?

A 
ilitation of the pupil increases the degree of pupillary block: increased Aqueous humor in posterior chamber
	o Increased pressure
	o Iris bulges forward : obliterates the angle :obstructs the trabeculae: high IOP
Transition from bright to dim lighting
-Anticholinergic meds
-Sympathomimetic meds
- Dilation for exam 
- Emotional upset
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5
Q

What is the typical presentation of AAG?

A 
Symptoms
	o Abrupt onset of severe eye pain
	o Blurred vision: halos around lights
	o Frontal headache
	o Nausea/Vomiting
	
Signs
	o Conjunctival injection
	o Corneal edema (cloudy appearance)
	o Fixed mid-dilated pupil
	o Decreased visual acuity
	o incr IOP
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6
Q

What is the endpoint goal of treating AACG?

A

IOP LT 35mmHg or a reduction GT 25% of presenting IOP

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7
Q

Outline the management of AAG?

A
  1. Block aqueous humor production:
    a. Topical BB: Timolol 0.5% I gtt q30min x 2
    b. Topical alpha-2 agonist: aproclonidine 1 gtt q30min x 2
    c. Carbonic anhydrase inhibitors: acetazolamide 500mg PO/IM/IV then 250mg q6h
  2. Reduce Volume:
    a. Mannitol 1-2g/kg
  3. Pupillary constriction to facilitate outflow
    a. Topical pilocarpine 2-4%: 1 gtt q15min x 1-2hrs
  4. Anti-inflammatory:
    a. Prednisolone 1% q15min x 2
  5. Prevention of valsalva and increased IOP:
    a. Analgesics: IV fentanyl
    b. Antiemetics: Zofran, maxeran
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8
Q

List 6 things that cause “flashes” or “floaters”:

A 
- Spots / Floaters:
	o Retinal break or detachment
	o Posterior vitreous detachment
	o Vitreous haemorrhage
	o Vitreous debris 
	o Posterior uveitis
	o Corneal opacity / FB
		
- Flashes of light:
	o Retinal break or detachment
	o Retinitis
	o Posterior vitreous detachment
	o Migraine
	o CNS disorder: occipital lobe pathology
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9
Q

List 5 things that cause acute painful vision loss:

A
  • Temporal arteritis
  • Acute angle closure glaucoma
  • Optic neuritis
  • Iritis
  • Endopthalmitis
  • Corneal hydrops (keratoconus)
  • Migraine with aura
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10
Q

List 5 reasons for post-traumatic vision loss:

A
  • Eyelid swelling
  • Corneal irregularity
  • Hyphema
  • Ruptured globe
  • Lens dislocation
  • Retinal detachment
  • Commotio retinae
  • Retinal haemorrhage
  • Vitreous haemorrhage
  • Traumatic optic neuropathy
  • CNS injury
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11
Q

What are the findings of central retinal artery occlusion

A

o Unilateral acute, painless vision loss
o Marked afferent pupillary defect
o Retina: edematous and pale grey/white
Fovea → cherry red spot

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12
Q

List risk factors for CRAO.

A
  • Carotid artery disease
  • HTN
  • Diabetes
  • Cardiac disease
  • Collagen vascular disease
  • Vascultis
  • Cardiac valvular abnormalities
  • Sickle cell disease
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13
Q

Outline the ED management of CRAO:

A
  • Dislodge embolus: Digital global massage
  • Increase retinal blood flow
    o Rebreathing into a paper bag (10min per hour)
    o Breath carbogen mixture (5% CO2 mixture)
  • Decrease IOP
    o Timolol 0.5% gtts 1 drop Q30min x2
    o Acetazolamide 500mg IV
  • Urgent Optho consult: anterior chamber paracentesis
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14
Q

List risk factors for CRVO.

A
  • HTN
  • DM
  • Hypercoaguable states
  • Hyperviscosity states
  • Papilledema
    Glaucoma
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15
Q

What are the findings of CRV occlusion on exam?

A 
Blood and Thunder”
			o Painless unilateral loss of vision
			o Diffuse retinal haemorrhage in all 4 quadrants
			o Tortuous, dilated retinal veins
			o Vascular leakage
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16
Q

Compare ischemic and non ischemic CRV occlusion

A

non-ischemic has mild changes with mild decr VA and absent afferent defect.
ischemic has dilated tortuous veins and hemorrhages, marked decr in VA and RAPD is present

17
Q

What are the 3 mechanisms of RETinal detachments?

A 
1. Rhegmatogenous
			o Tear or a hole in the neuronal layer → fluid leaks between the layers
			o Trauma may cause tears
			o Occurs in pts older than 45yrs
			o Associated with degenerative myopia
			o Most common à floaters, flashes, curtain / shadow visual loss
	2. Exudative
			o Fluid or blood leakage from vessels within the retina
			o HTN
			o Pre-eclampsia / Eclampsia
			o CRV occlusion
			o Glomerulonephritis
			o Papilledema
			o Vasculitis
			o Choroidal tumor
	3. Tractional 
			o Fibrous band formation in the vitreous → contraction and detach the retina
			o Causes:
		i. Proliferative diabetic retinopathy
		ii. Sickle cell retinopathy
		iii. Toxocariasis
		iv. Trauma
		v. Previous giant retinal tear
18
Q

List 5 causes of vitreous haemorrhage:

A
  • Retinal detachment
  • Posterior vitreous detachment
  • MCC diabetic retinopathy
  • Retinal tears
  • Neovascularization
  • Sickle cell
  • Macular degeneration
  • Trauma
19
Q

Outline an approach to neuro-opthalmic visual loss:

A
  1. Prechiasmal Visual Loss
    a. Optic Neuritis
    b. Ischemic Optic Neuritis (Temporal Arteritis)
    c. Compressive Optic Neuritis
    d. Toxic/Metabolic Optic Neuritis
  2. Chiasmal Visual Loss
    a. Chiasmal compression (pituitary tumors, craniopharyngioma, or meningioma)
    b. *bitemporal hemianopsia
  3. Postchiasmal Visual Loss
    a. Infarction
    b. Tumor
    c. Arteriovenous malformation
    d. Migraine disorders
20
Q

List 8 causes of RAPD:

A 
- Retina: 
	o Ischemic retina
	o CRAO
	o CRVO
	o Giant cell arteritis
	o Severe macular degeneration
	o Retinal tumor
	o Retinal detachment (if large)
	o Retinal infection
	o MeOH
- Optic nerve: 
	o Infection
	o Inflammation
	o Tumor
	o Post-op
	o Trauma
	o GCA
	o XRT (external beam radiation therapy)
21
Q

What is the classic post chiasmal visual field defect?

A

Homonymous hemianopsia (spares macula)

22
Q

What are 2 ocular manifestations of MS

A

Internuclear opthalmoplegia

optic neuritis

23
Q

What are the toxic and metabolic causes of optic neuropathy?

A 
Toxic 
	o Barbiturates
	o Chloramphenicol
	o Emetine
	o Ethambutol
	o Ethylene glycol
	o Methanol
	o Isoniazid
	o Heavy metals
Metabolic
	o Thiamine
Pernicious anaemia (B12)
24
Q

List 5 causes of anisocoria:

A
  • Horners
  • CN III palsy
  • Adie’s pupil (unilateral or bilateral, associated with ↓knee jerk and absence of sweating)
  • Argyl robertson pupil
  • Benign anisocoria
  • Pharmacologic
  • Traumatic mydriasis
25
Q

What is an argyll robertson pupil

A

Argyl Robinson Pupil
o Syphilitic pupil AKA “Prostitute’s pupil”
o Don’t constrict with light, but do with accomodationBilateral
o Sign of tertiary syphillis

26
Q

What is Hutchinson’s sign?

A
  • VZV involvement of the nasociliary nerve; Zoster lesions on the tip of the nose
  • High risk of ocular VZV involvement (76% risk vs. only 34% if not seen).
  • Tx: admit, systemic acyclovir
    Newer studies saying that oral valcyclovir and outpt treatment may be appropriate.
27
Q

What are sources of radiation burns, and how do they present?

A 
o Sources:
			o UV light from the sun
			o Tanning booths
			o High altitude
Welder’s ar
28
Q

What is the treatment for mechanical abrasions?

A 
o Cycloplegics
	o Topical NSAIDs - acular
	o And topical antibiotics – erythromycin, gentamycin, polysporin
	o Oral pain medications
FU with ophthalmology in 24h
29
Q

What causes hyphema, and how are they graded?

A
  • Disruption of the blood vessels in the iris or ciliary body
  • Grading:
    o 1 = 1/3
    o 2 = up to half
    o 3 = below full
    o 4 = full eight ball

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