Ophthalmology Flashcards
(29 cards)
How does aqueous humor travel through the eye
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
What is the difference between closed and open angle glaucoma?
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
What is secondary angle closure glaucoma?
- Acute glaucoma secondary to o Synechia o Lens dislocation o Intraocular tumours o Central Retinal Vein Occlusion
What factors can precipitate an episode of acute angle glaucoma?
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
What is the typical presentation of AAG?
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
What is the endpoint goal of treating AACG?
IOP LT 35mmHg or a reduction GT 25% of presenting IOP
Outline the management of AAG?
- 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 - Reduce Volume:
a. Mannitol 1-2g/kg - Pupillary constriction to facilitate outflow
a. Topical pilocarpine 2-4%: 1 gtt q15min x 1-2hrs - Anti-inflammatory:
a. Prednisolone 1% q15min x 2 - Prevention of valsalva and increased IOP:
a. Analgesics: IV fentanyl
b. Antiemetics: Zofran, maxeran
List 6 things that cause “flashes” or “floaters”:
- 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
List 5 things that cause acute painful vision loss:
- Temporal arteritis
- Acute angle closure glaucoma
- Optic neuritis
- Iritis
- Endopthalmitis
- Corneal hydrops (keratoconus)
- Migraine with aura
List 5 reasons for post-traumatic vision loss:
- Eyelid swelling
- Corneal irregularity
- Hyphema
- Ruptured globe
- Lens dislocation
- Retinal detachment
- Commotio retinae
- Retinal haemorrhage
- Vitreous haemorrhage
- Traumatic optic neuropathy
- CNS injury
What are the findings of central retinal artery occlusion
o Unilateral acute, painless vision loss
o Marked afferent pupillary defect
o Retina: edematous and pale grey/white
Fovea → cherry red spot
List risk factors for CRAO.
- Carotid artery disease
- HTN
- Diabetes
- Cardiac disease
- Collagen vascular disease
- Vascultis
- Cardiac valvular abnormalities
- Sickle cell disease
Outline the ED management of CRAO:
- 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
List risk factors for CRVO.
- HTN
- DM
- Hypercoaguable states
- Hyperviscosity states
- Papilledema
Glaucoma
What are the findings of CRV occlusion on exam?
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
Compare ischemic and non ischemic CRV occlusion
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
What are the 3 mechanisms of RETinal detachments?
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
List 5 causes of vitreous haemorrhage:
- Retinal detachment
- Posterior vitreous detachment
- MCC diabetic retinopathy
- Retinal tears
- Neovascularization
- Sickle cell
- Macular degeneration
- Trauma
Outline an approach to neuro-opthalmic visual loss:
- Prechiasmal Visual Loss
a. Optic Neuritis
b. Ischemic Optic Neuritis (Temporal Arteritis)
c. Compressive Optic Neuritis
d. Toxic/Metabolic Optic Neuritis - Chiasmal Visual Loss
a. Chiasmal compression (pituitary tumors, craniopharyngioma, or meningioma)
b. *bitemporal hemianopsia - Postchiasmal Visual Loss
a. Infarction
b. Tumor
c. Arteriovenous malformation
d. Migraine disorders
List 8 causes of RAPD:
- 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)
What is the classic post chiasmal visual field defect?
Homonymous hemianopsia (spares macula)
What are 2 ocular manifestations of MS
Internuclear opthalmoplegia
optic neuritis
What are the toxic and metabolic causes of optic neuropathy?
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)
List 5 causes of anisocoria:
- 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
