Visual Loss Flashcards
What are the causes of SUDDEN visual loss?
Vascular: retinal artery/vein occlusion, amaurosis fugax, ischaemic optic neuropathy Vitreous haemorrhage Retinal detachment Age related macular degeneration (wet) Acute angle closure glaucoma Optic neuritis Giant cell arteritis
What are the causes of gradual visual loss?
Cataract Age related macular degeneration (dry) Chronic open angle glaucoma Diabetic retinopathy Refractive error
What are the clinical features of central retinal artery occlusion (CRAO)?
Sudden, profound, painless vision loss
–> like a curtain coming down
RAPD
Pale, swollen retina with cherry red spot at macula
Thread like vessels
What are the causes of CRAO?
GCA –> always rule this out
Embolic e.g. heart valve, thrombus
Carotid artery disease
(it is a form of stroke)
How quickly must a CRAO be treated?
Only effective if treated within 12-24 hours
Although retina technically dies within 90 minutes
What are the treatment options for CRAO?
Aim to dislodge blockage + restore circulation:
- ocular massage
- paper bag breathing
- IV Diamox
- anterior chamber paracentesis
What does a branch retinal artery occlusion look like?
Only part of the retina affected –> pale window
May see the embolus on fundoscopy
What is amaurosis fugax?
Transient CRAO (like a TIA)
What are the features of amaurosis fugax?
Transient painless loss of vision –> like a curtain coming down
Lasts about 5 minutes with full recovery
Examination normal
What should be done for suspected amaurosis fugax?
Refer to stroke clinic
What are the clinical features of central retinal vein occlusion?
Sudden, painless visual loss
RAPD
Retinal flame haemorrhages (stormy sunset) Tortuous vessels Swollen disc Cotton wool spots Neovascularisation if longstanding
How is central retinal vein occlusion managed?
No signs of ischaemia: - observe every 3 months Ischaemia but no neovascularisation: - observe closely every 4-6 weeks Ischaemia + neovascularisation: - urgent argon laser pan-retinal photocoagulation
What is ischaemic optic neuropathy?
Occlusion of the optic nerve head circulation –> infarction of the optic nerve head
Which arteries are occluded in ischaemic optic neuropathy?
Posterior cilliary arteries
Which condition must be ruled out as the cause of ischaemic optic neuropathy?
Giant cell arteritis
Where does the bleeding come from in a vitreous haemorrhage?
Abnormal vessels:
- e.g. retinal ischaemia in DM or CRVO –> new, fragile vessels
OR normal retinal vessels:
- e.g. bridging a retinal tear
What are the features of a vitreous haemorrhage?
Loss of vision
Floaters
Loss of red reflex
May see haemorrhage on fundoscopy
What are the features of retinal detachment?
Persistent flashing lights
Burst of new floaters
Dark shadow in peripheral vision, increasing in size
How does retinal detachment occur?
Most commonly due to separation of vitreous gel from retina
- traction –> retinal tear –> detachment
How is a retinal detachment managed?
If picked up early as a tear –> laser therapy
If retina detached –> surgery required
What are the surgical options for repairing a retinal detachment?
Most common:
- internal approach with vitrectomy/laser or cryotherapy/bubble of gas to act as tamponade
In very young patients:
- external approach with scleral bubble
What are the symptoms of optic neuritis?
Variable loss of vision over a few days
Washed out colour vision
Dull ache on eye movements
What might be seen on examination of a patient with optic neuritis?
Decreased visual acuity RAPD Reduced colour vision Increased blind spot Optic disc swelling
What is the most common cause of optic neuritis?
MS
What is the most common cause of blindness in the western world?
Age related macular degeneration (ARMD)
How do macular problems affect vision?
Cause changes in CENTRAL vision
What causes dry ARMD?
Wear and tear of retinal pigment epithelium
What are the clinical features of dry ARMD?
Gradual decline in VA
Central vision missing –> scotoma
Drusen - build up of waste products below retinal epithelium
Atrophic patches of retina
What is the management for dry ARMD?
Supportive (no active treatment):
- visual aids
- dietary/smoking advice
- Amsler grid
- blind registration
What causes wet ARMD?
Eye grows new blood vessels (neovascularisation) within the macula to ‘repair’ dry ARMD
- vessels then leak fluid or bleed into retinal tissue
What are the clinical features of wet ARMD?
SUDDEN devastating drop in central VA
Associated metamorphopsia (distortion)
Haemorrhage + exudate
Which investigations may be done for wet ARMD?
Ocular coherence tomography (OCT)
Fundus fluorescence angiography
What is the treatment for wet ARMD?
Intravitreal injection of anti-VEGF (Ranibizumab)
How does anti-VEGF work?
Aborts growth of abnormal vessels
Shrinkage of neovascular membrane
Reduced fluid leakage/bleeding into tissue
What is a cataract?
Cloudiness of the lens –> gradual blurring of vision
What are the causes of cataract?
Age related (most common) Congenital Traumatic (blunt or penetrating injury) Metabolic (diabetes) Drug induced (steroids) Intra-uterine infection (rubella, CMV, toxoplasmosis)
What is the treatment for cataract?
Surgery: phaco-emulsification with intra-ocular lens implantation
How does cataract surgery work?
Phaco breaks up cataract using ultrasound
Lens fragments removed portion by portion
Artificial IOL inserted
Wounds are self healing
What are the different types of refractive error?
Myopia
Hypermetropia
Astigmatism
Presbyopia
What does myopia mean?
Short sighted (can’t see far away)
What does hypermetropia mean?
Long sighted (can’t see near)
What does presbyopia mean?
Age related loss of accommodation
What is astigmatism?
Irregular corneal curvature –> light not focused evenly on retina
What is the management for refractive error?
Glasses/contact lenses
