Visual Loss Flashcards
7 causes of sudden visual loss?
Central retinal artery occlusion Central retinal vein occlusion Occlusion of optic nerve circulation Vitreous haemorrhage Retinal Detachment Wet ARMD Closed angle glaucoma
4 causes of gradual visual loss?
Cataracts
Dry ARMD
Open angle glaucoma
Refractive errors
What does a positive RAPD mean?
A positive RAPD means there are differences between the two eyes in the afferent pathway due to retinal or optic nerve disease.
How is a RAPD test done?
Swinging-flashlight test whereupon the patient’s pupils dilate when a bright light is swung from the unaffected eye to the affected eye. As to affected eye less light is perceived so the pupils need to constrict less.
What is virchows triad? How does this relate to retinal vein occlusion?
Three broad categories of factors that are thought to contribute to thrombosis. Hypercoagulability. Hemodynamic changes (stasis, turbulence) Endothelial injury/dysfunction.
Endothelial damage in diabetes
Abnormal blood flow in hypertension
Hypercoaguable state in cancer
Central retinal artery occlusion is a form of _____
stroke and patients may have carotid artery disease
Central retinal artery occlusion is associated with _____________________
Atherosclerosis and hypertension
Occasionally GCA but this is more likely to effect blood supply to the optic nerve
Presentation of central retinal artery occlusion?
Sudden painless loss of vision
Positive RAPD test
On exam may see pale oedematous retina due to ischaemia and a cherry red spot
What is amaurosis fugax?
A form of retinal artery occlusion that causes transient painless visual loss and lasts 5 mins with a full recovery, need referred to the stroke clinic
Management of central retinal artery occlusion?
Ophthalmic emergency
Need to find cause
Ocular massage to dislodge emboli, paracentesis, dilation of arteries, acetazolamide
Unfortunately rarely recovers
What happens in central retinal vein occlusion?
Occlusion of central retinal vein causes obstruction in outflow of blood and get a rise in intravascular pressure
Predisposing factors to central retinal vein occlusion?
Age, hypertension, CV disease, glaucoma, blood disorders
Presentation of central retinal vein occlusion?
Sudden, painless visual loss
On exam: retinal haemorrhages, dilated torturous veins, swollen disc and macula
Contrast appearance of eye in CRVO and CRAO?
Vein: retinal haemorrhages, dialled torturous veins, swollen disc and macula > BACK-FLOW OF BLOOD AND RISE IN PRESSURE
Artery: pale oedematous retina and cherry red spot > ISCHAEMIA
Management of CRVO?
Find underlying cause
If neovascularisation can do photocoagulation or anti-VEGF intravitreal injection
What is more common CRVO or CRAO?
CRVO by far
What is ischaemic optic neuropathy?
Occlusion of the optic nerve head circulation
Get occlusion of the posterior ciliary arteries by GCA or atherosclerotic/ hypertensive disease
2 causes of ischaemic optic neuropathy?
GCA
Atherosclerosis/ hypertension
Presentation of ischaemic optic neuropathy?
Sudden visual loss usually painless
Pale swollen optic disc > may be splinter haemorrhages
RAPD test positive
Management of ischaemic optic neuropathy?
Prednisolone 40-60 mg in GCA
No exact treatment for non GCA type
What is the red reflex?
Pupil goes red when light shone as lights up blood rich retina. Pathologies that effect vitreous, cornea or retina can cause loss e.g. haemorrhage as covering the retina
What is vitreous haemorrhage and the causes?
Bleeding from the retinal blood vessel into the vitreous gel due to:
- proliferative diabetic retinopathy
- any other cause of retinal or optic disc neovascularisation e.g. branch RVO
- spontaneous tearing of retina (may precede retinal detachment)
- systemic hypertension
Presentation of vitreous haemorrhage?
Painless loss of vision, may get floaters
On exam: partial or total loss of red reflex, haemorrhage visible
Management of vitreous haemorrhage?
Identify underlying cause
May resolve spontaneously, may need vitrectomy
What is a scotoma?
a partial loss of vision or blind spot in an otherwise normal visual field
What happens in retinal detachment?
Separation of the 2 embryonic layers of the retina (the neuroretina from the pigment epithelium). Pigment epithelium layer is the layer that nourishes the retinal visual cells. Neuroretina contains the photoreceptors. Retina is classed as neuroretina.
Predisposing factors to retinal detachment?
Increasing age
Myopia
Lattice degeneration of the retina
Mechanical trauma
Presentation of a retinal detachment?
Painless loss of vision > depends on where the detachment affects. Primary shadow that increases. Sudden onset of floaters as the separation occurs or flashes of light. On exam the detached retina is elevated and grey in colour.
Management of retinal detachment?
Surgery
Needs quick treatment
What is Age related macular degeneration?
Commonest cause of blindness, multifactorial (age, hypertension, smoking, UV) and causes degeneration of the macula and therefore central vision
Wet/ Neovascular Macular degeneration causes sudden or gradual visual loss?
Sudden
Dry/ atrophic macular degeneration causes sudden or gradual visual loss?
Gradual
Describe what happens in Wet ARMD? What will eye look like?
New blood vessels grow and leakage causes build up of fluid and scarring
may see haemorrhages and exudates on exam
Presentation of wet ARMD?
Rapid central visual loss and distortion
Treatment of wet ARMD?
Anti VEGF intravitreal injections aims to convert wet ARMD to dry ARMD which will cause more gradual visual loss.
Describe what happens in Dry ARMD? What will the eye look like?
Build up of druse (lipid deposits) behind the retina. Drusen can be hard or soft and may be focal RPE detachment, can get atrophic patches of the retina
Macular degeneration causes central or peripheral visual loss?
Central
Treatment of ARMD?
No cure
Treatment is supportive with low vision aids, magnifiers and social support
What is glaucoma?
Condition caused by increased pressure inside the eye that is sufficiently elevated to cause optic nerve damage and result in visual field defects with loss of sight.
What are some risk factors for primary open angle glaucoma?
Age, Race (black africans more at risk), positive family history, myopia
What angle is being referred to in glaucoma?
Angle between the cornea and iris
Primary open angle glaucoma causes gradual or sudden visual loss?
Gradual loss of peripheral vision (central vision is preserved until late on)
What happens in primary open angle glaucoma?
High intraocular pressure resulting from reduced outflow of aqueous humour through the trabecular meshwork
Presentation of primary open angle glaucoma?
Gradual, insidious painless loss of peripheral vision
Initially asymptomatic and identified during ophthalmic exam
Optic disc shows enlarged cup with a thin neuroretinal rim (increased cup to disc ratio)
Visual fields show a normal blind spot with scotomas
What does treatment for POAG aim to do?
Reduce aqueous production or increase drainage
5 examples of drugs for POAG?
Beta blockers reduce aqueous production (end in lol)
Prostaglandin analogues increase aqueous outflow (end in prost)
Carbonic anhydrase inhibitors reduce aqueous production (amide)
Alpha 2 adrenergic agonists reduce production and increase drainage (brimonidine)
Parasympathomimetics (pilocarpine) increase drainage
What causes acute angle closure glaucoma?
Sudden rise in intraocular pressure due to reduced aqueous drainage when the lens pushes the iris forward against the trabecular meshwork
Acute angle closure glaucoma causes sudden or gradual visual loss?
Sudden
Presentation of acute angle closure glaucoma?
Painful, red eye, sudden visual loss, headache, nausea, vomiting, cloudy cornea (due to water logging), dilated pupil (iris sphincter can’t work properly), long sighted
Long sighted person, cloudy cornea, dilated pupil, visual loss, painful eye?
Acute angle closure glaucoma
Treatment of acute angle closure glaucoma?
Refer to ophthalmologist, pilocarpine eye drops and oral acetazolamide (carbonic anhydrase inhibitor) to reduce production of aqueous humour. Definitive treatment involves making a whole in the periphery of the iris by lazer or surgical means.
What is a cataract?
Opacification of the lens due to abnormal changes in lens proteins.
Causes of cataracts?
Many different causes, can be congenital but majority are age related
Presentation of cataract?
Gradual visual loss/ blurring
Cloudy lens
Partial or full loss of red reflex
Treatment of cataracts?
Early changes are correctable by glasses by eventually need surgical intervention
Small-incision extra capsular or phacoemulsification cataract extraction with insertion of an intraocular lens is treatment of choice
Define a refractive error?
Any abnormality in the focusing mechanism of the eye as opposed to an opacity of the system
Define emmetropic?
Eye with no refractive errors
Point of focus is on the retina
Define myopia?
Short sighted
Eye point of focus is in front of the retina so objects far away looked blurred
How is myopia corrected?
Using a concave negative lens (causes divergence of light so hits a point further away)
Define hypermetropia?
Eye point of focus is behind the rent so objects up close appear blurred
How is hypermetropia corrected?
Corrected using a convex (positive lens) (causes convergence of lights so hits a point closer)
What happens in presbyopia?
Ageing of the lens, it becomes less able to alter its curvature causing difficulty with near vision. Need reading glasses.
What is astigmatism?
Error where there are different degrees of refraction in different meridians of curvature. So can be myopic in one plane, hypermetropic or emmetropic in the other plane. Eye has multiple focal points.
Treatment of astigmatism?
Treat with contact lens or surgery
What type of investigation can be used to look at macular disease?
OCT optical coherence tomography - helps distinguish between wet and dry ARMD and other pathologies
Red flag for someone with optic neuritis?
loss of colour vision in a young patient as sign of MS
What are synechiae?
Synechiae are adhesions between the pupil and iris and can lead to a small/irregular pupil.
What is a hypopyon?
Inflammatory cells in anterior chamber usually a sign of significant intraocular inflammation
What is a hyphaema? Causes?
Collection of blood in the anterior chamber of the eye usually caused by trauma