Visual Loss Flashcards
Acute visual loss - common and rare causes?
Common - AACG, CRAO, vitreous haemorrhage, CVA/TIA
Rarer - temporal arteritis, retinal detachment, CRVO, optic neuritis, anterior ischaemic optic neuropathy
What is optic neuritis
Ix / Tx?
Demyelination of the optic nerve, often the first presentation of MS
Headache, painful eye movements, flashes, visual loss in one eye over a few days
Previous episodes, symptoms of MS, young female, positive MS family history
Exam: reduced visual acuity, visual fields and colour vision, RAPD, swollen/blurred disc (OPTIC DISC SWELLING)
Refer to neuro for MRI and give analgesia
What is vitreous haemorrhage?
Ix / Tx?
Bleed from retina into vitreous
Sudden loss of vision in one eye
Preceding flashes / floaters, CV disease risk factors, head trauma
Absent red reflex, unable to visualise fundus
Ix: USS. Tx: usually spontaneously reabsorbed but consider vitrectomy in large bleeds
What is anterior ischaemic optic neuropathy (AION)?
Ix / Tx?
Visual loss secondary to optic nerve ischaemia, can be arteritic (AAION) or non-arteritic (NA-AION).
AAION is ischaemic due to temporal arteritis, a medium-vessel vasculitis affecting those >50 years of age
NA-AION more common, usually slightly younger (60s > 70s), more likely if CV disease risk factors, male, clotting disorders.
Symptoms: sudden onset painless blurred vision in one eye, usually upper or lower visual field affected.
Exam: RAPD, reduced acuity, visual field loss, swollen disc
Ix: exclude temporal arteritis, screen clotting disorders and CV risk factors.
Mgmt: control risk factors, refer to ophth.
Causes of gradual visual loss?
Usually progressive and irreversible
Refractive errors Cataracts Age-related macular degeneration Primary open angle glaucoma Diabetic maculopathy
Refractive errors
Add in
What are cataracts?
Ix / Tx?
Gradual opacity of lens, most common cause reversible blindness. Gradual-onset blurred vision, reduce colour vision, glare (lights appear brighter) and halos around light
Most commonly caused by increased age. Also associated with: sunlight (UV) exposure, smoking, alcohol, trauma, diabetes, LONG-TERM CORTICOSTEROIDS, radiation, myotonic dystrophy, HYPOCALCAEMIA,
Exam: reduced red reflex, difficult to visualise fundus.
Ix: opthlamoscopy after pupil dilation - normal fundus and optic nerve, slit lamp - visible cataracts
How are cataracts classified?
Nuclear: change lens refractive index, common in old age
Polar: localized, commonly inherited, lie in the visual axis
Subcapsular: due to steroid use, just deep to the lens capsule, in the visual axis
Dot opacities: common in normal lenses, also seen in diabetes and myotonic dystrophy
Management of cataracts?
And its complications?
In early stages, age-related cataracts can be managed conservatively (stronger glasses/contacts, using brighter lighting. Optimises vision but does not slow progression, therefore surgery eventually needed).
Surgical extraction - only effective Tx, phacoemulsification - US to fragment lens, then suctioning it out, before inserting an artificial replacement
NICE suggests that referral for surgery should be dependent upon whether a visual impairment is present, impact on QoL and patient choice. Whether bilateral, possible risks and benefits. Prior to surgery, patients provide info on refractive implications of various types of intraocular lenses. After surgery, advise on use of drops and eyewear, what to do if vision changes and mgmt of other ocular problems.
High success rate: 85-90% of pts achieving 6/12 corrected vision (on a Snellen chart) postoperatively.
Complications following surgery
Posterior capsule opacification: thickening of the lens capsule
Retinal detachment
Posterior capsule rupture
Endophthalmitis: inflammation of aqueous and/or vitreous humour
What is age-related macular degeneration?
Commonest cause of blind registration in UK, progressive loss of central vision, currently affects 1% of population but rising
Wet or dry
What is DRY AMD?
Retinal pigment epithelium atrophy, degeneration of photoreceptors
Gradual distortion and loss of central vision
Risk factors: Smoking, >50, female, Caucasian
Exam: well define deposits on macula (drusen), central scotoma, distorted lines on Amsler grid
Slow progression, currently no Tx to halt visual deterioration - managed with low vision aids, lifestyle changes
What is WET AMD?
Neovascularisation of choroidal vessels into retina, RAPID distortion and loss of central vision.
Risk factors: Smoking, >50, female, Caucasian
Exam: distorted macula, haemorrhages, central scotoma, distorted lines on Amsler
Ix: Amsler grid, fluorescein angiography, retinal OCT
Fast progression, new vessels haemorrhage into viterous and obstruct vision
Intravitreal anti-VEGF (ranibizumab) to reduce neovascularisation
What is primary open angle glaucoma?
Risk factors / examination?
Progressive optic neuropathy - characteristic ‘cupping’ of optic disc and visual field defect. Often asymptomatic, usually detected by opticians
Loss of nerve fibres running from retina to optic nerve –> thinner ‘cup’ surrounding vessels at the disc
Risk: age, family history, Afro-Caribbean
Exam; visual field defects, optic disc cupping, increased IOP (usually)
Treatment of primary open angle glaucoma?
Lowering IOP only way to slow progression.
Medical: Latanoprost (prostaglandin analogue) Timolol (B-blocker), Brimonidine (a-agonist), Pilocarpine (muscarinic agonist), Acetazolamide (carbonic anhydrase inhibitors)
Surgical: trabeculectomy (surgical drainage channel out of anterior chamber)
Laser: trabeculoplasty (enhances aqueous drainage), ciliary body destruction (reduces aqueous production)
What is secondary glaucoma?
Angle open but trabecular meshwork blocked by:
- inflammatory cells e.g. uveitis
- blood vessels (iris neovascularisation secondary to retinal ischaemia in proliferative diabetic retinopathy)
- iris pigment (e.g. pigment dispersion syndrome)
Long-term topical steroids can increase IOP and cause irreversible disc damage
