Transient/ Acute Vision Loss
Transient (seconds to hours)
TIA
Migraine
Acute (seconds to days)
Trauma/Foreign Body
Complications
NOTE: Topical analgesics should only be used to facilitate examination. They should NEVER be used as treatment for any ocular problem
Central retinal artery occlusion (CRAO)
Aetiology
Clinical Features
Central/ Branch Retinal Vein Occlusion (CRVO/ BRVO)
Retinal Detachment
Clinical Features
Source
Toronto Notes 2012
TIA
Migraine
Acute (seconds to days)
Trauma/Foreign Body
- Foreign material in or on cornea
- May have associated rust ring if metallic
- Patients may note tearing, photophobia, foreign body sensation, red eye
- Signs include foreign body, conjunctival injection, epithelial defect that stains with fluorescein, corneal oedema, anterior chamber cells/flare
Complications
- Abrasion, infection, scarring, rust ring, 2° iritis
- Remove under magnification using local anesthetic and sterile needle or refer to ophthalmology (depending on depth and location)
- Treat as per corneal abrasion (topical abx, topical NSAIDs, topical cycloplegic)
NOTE: Topical analgesics should only be used to facilitate examination. They should NEVER be used as treatment for any ocular problem
Central retinal artery occlusion (CRAO)
Aetiology
- Thromboemboli
- Temporal arteritis (GCA)
Clinical Features
- Sudden, painless (except in GCA), severe monocular loss of vision
- RAPD
- +/- Amaurosis fugax hx
- "cherry-red spot" at centre of macula (visualization of unaffected highly vascular choroid through the thin fovea)
- Retinal pallor
- Narrowed arterioles, boxcarring (segmentation of blood in arteries)
- Cotton-wool spots (retinal infarcts)
- Cholesterol emboli (Hollenhorst plaques)- usually located at arteriole bifurcations
- After -6 wks: cherry-red spot recedes and optic disc pallor becomes evident
- OCULAR EMERGENCY: attempt to restore blood flow within 2 h
- The sooner the treatment = better prognosis (irreversible retinal damage if >90 min of complete CRAO)
- Massage the globe (compress eye with heel of hand for 10 s, release for 10 s, repeat for 5 min) to dislodge embolus
- Decrease intraocular pressure
- Topical beta-blockers
- Inhaled oxygen-carbon dioxide mixture
- IV acetazolamide
- IV mannitol (draws fluid from eye)
- Drain aqueous fluid- anterior chamber paracentesis (carries risk of endophthalmitis)
- Treat underlying cause to prevent CRAO in other eye
- Follow up 1 month to rule out neovascularization
Central/ Branch Retinal Vein Occlusion (CRVO/ BRVO)
- Second most frequent "vascular" retinal disorder after diabetic retinopathy
- Usually a manifestation of a systemic disease (e.g. hypertension, diabetes mellitus)
- Thrombus occurs within the lumen of the blood vessel
- Arteriosclerotic vascular disease
- Hypertension
- Diabetes mellitus
- Glaucoma
- Hyperviscosity (e.g. polycythemia rubra vera, sickle-cell disease, lymphoma, leukemia)
- Drugs (e.g. oral contraceptive pill, diuretics)
- Painless, monocular, gradual or sudden visual loss
- ± RAPD
- "Blood and thunder" appearance
- Diffuse retinal haemorrhages, cotton-wool spots, venous engorgement, swollen optic disc, macular oedema
- Venous stasis/non-ischemic retinopathy
- No RAPD, VA approximately 6/24
- Mild haemorrhage, few cotton wool spots
- Resolves spontaneously over wks to months
- May regain normal vision if macula intact
- Haemorrhagic/ischemic retinopathy
- Usually older patient with deficient arterial supply
- RAPD, VA approximately 20/200, reduced peripheral vision
- More hemorrhages, cotton wool spots, congestion
- Poor visual prognosis
- Degeneration of retinal pigment epithelium
- Neovascularisation of retina and iris (2° rubeosis), leading to 2° glaucoma
- Vitreous haemorrhage
- Macular oedema
- No treatment available to restore vision in CRVO/BRVO
- Treat underlying cause/contributing factor
- Fluorescein angiography to determine extent of retinal non-perfusion= risk of neovascularisation
- Retinal laser photocoagulation, or intravitreal anti-VEGF injection to reduce retinal or iris neovascularisation and prevent neovascular glaucoma
- Macular grid laser photocoagulation for the treatment of macular edema in BRVO, not CRVO,
- Intravitreal or slow-release biodegradable corticosteroid, or anti-VEGF injection is effective in the treatment of macular oedema in both CRVO and BRVO
Retinal Detachment
- Cleavage in the plane between the neurosensory retina and the retinal pigment epithelium (RPE)
- Rhegmatogenous (most common):
- Caused by a tear or hole in the neurosensory retina, allowing fluid from the vitreous to pass into the sub retinal space
- Tears may be caused by posterior vitreous detachment (PVD), degenerative retinal changes, trauma or iatrogenically
- Incidence increases with advancing age, in high myopes and after ocular surgery/trauma
- Tractional
- Caused by traction (due to vitreal, epiretinal, or sub retinal membrane) pulling the neurosensory retina away from the underlying RPE
- Found in conditions such as DR, CRVO, sickle cell disease, ROP, and ocular trauma
- Exudative
- Caused by damage to the RPE resulting in fluid accumulation in the subretinal space
- Main causes are intraocular tumours, posterior uveitis, central serous retinopathy
Clinical Features
- Sudden onset
- Flashes of light (due to mechanical stimulation of the retinal photoreceptors)
- Floaters (hazy spots in the line of vision which move with eye position, due to drops of blood from torn vessels bleeding into the vitreous)
- Curtain of blackness/peripheral field loss
- Darkness in one field of vision when the retina detaches in that area
- Loss of central vision (if macula "off")
- Decreased I0P (usually 4-5 mmHg lower than the other, normal eye)
- Ophthalmoscopy: detached retina is grey-white with surface blood vessels, loss of red reflex
- ± RAPD
- Prophylactic: symptomatic tear (flashes or floaters) can be sealed off with laser I cryotherapy, with the goal of preventing progression to detachment
- Therapeutic
- Rhegmatogenous
- Scleral buckle procedure
- Pneumatic retinopexy
- Both above treatments are used in combination with localization of retinal tears/holes and subsequent treatment with diathermy, cryotherapy or laser to create adhesions between the RPE and the neurosensory retina
- Vitrectomy plus injection of silicone oil in cases of recurrent detachment
- Tractional
- Vitrectomy ±membrane removal/scleral buckling/injection of intraocular gas as necessary
- Exudative
- Treat underlying cause
- Loss of vision, vitreous hemorrhage, recurrent retinal detachment
- A retinal detachment is an emergency, especially if the macula is still attached (macula "on")
- Prognosis for visual recovery varies inversely with the amount of time the retina is detached and whether the macula is attached or not
Source
Toronto Notes 2012