Acute Vision Loss

Acute vision loss is defined as a sudden decrease in vision (minutes to days). Important causes include vascular events (occlusions), retinal pathology (detachment, vitreous haemorrhage), optic nerve lesions (neuritis, ischaemia), and acute ocular conditions (acute glaucoma, corneal pathology).

Vascular Causes

1. Central Retinal Artery Occlusion (CRAO)

   • Presentation: Sudden, painless monocular vision loss (“like a curtain descending”)

   • Fundoscopy: Pale retina with a cherry red spot at the fovea

   • Urgency: Ophthalmic emergency; immediate referral (possible ocular massage, lowering IOP, search for embolic source)

   • Associated Factors: GCA in older patients, carotid atheroma, cardiac emboli

2. Central Retinal Vein Occlusion (CRVO)

   • Presentation: Sudden, painless monocular loss of vision

   • Fundoscopy: “Blood and thunder” appearance (widespread retinal haemorrhages, dilated veins, cotton wool spots)

   • Risk Factors: Hypertension, diabetes, hyperlipidaemia, glaucoma

   • Management: Urgent ophthalmology referral (possible intravitreal anti-VEGF injections), address cardiovascular risk factors

3. Amaurosis Fugax

   • Presentation: Transient monocular “blackout” of vision, often described as a curtain coming down then lifting

   • Cause: Embolic phenomenon from carotid or cardiac source

   • Workup: Carotid Doppler, echocardiogram, vascular risk assessment (lipids, BP, glucose)

4. Giant Cell Arteritis (GCA)

   • Presentation: Vision loss (often sudden), headache, scalp tenderness, jaw claudication, age >50

   • Lab findings: Elevated ESR and CRP

   • Management: Immediate high-dose corticosteroids to prevent further or bilateral vision loss, urgent temporal artery biopsy

Retinal Causes

1. Retinal Detachment

   • Symptoms: “Curtain” or veil spreading across vision, flashes, floaters

   • Risk Factors: Myopia, trauma, previous ocular surgery

   • Management: Urgent ophthalmology referral (laser, surgical repair)

2. Posterior Vitreous Detachment (PVD)

   • Symptoms: Flashes, floaters; usually mild vision disturbance unless retinal tear/detachment ensues

   • Management: Ophthalmology assessment to exclude retinal detachment

3. Vitreous Haemorrhage

   • Presentation: “Red-tinted” vision, sudden floaters, severe blurring

   • Causes: Diabetic retinopathy, retinal tear, trauma

   • Management: Treat underlying cause (urgent referral if vision severely compromised)

Neurological Causes

1. Optic Neuritis

   • Presentation: Subacute vision loss, often painful with eye movement; reduced colour vision (red desaturation)

   • Association: Multiple sclerosis, autoimmune conditions

   • Management: Neuro-imaging (MRI) if indicated, high-dose IV steroids can hasten recovery

2. Posterior Circulation Stroke

   • Presentation: Visual field defects (often bilateral or homonymous), ataxia, possible brainstem signs (dizziness, dysarthria)

   • Management: Urgent neuroimaging (CT/MRI), stroke protocol

Ocular Causes

1. Acute Angle-Closure Glaucoma

   • Presentation: Severe eye pain, nausea/vomiting, halos around lights, red eye, mid-dilated pupil non-reactive

   • Management: Emergency; reduce intraocular pressure (e.g. IV acetazolamide), urgent ophthalmology review

2. Corneal Ulcer/Oedema

   • Presentation: Pain, photophobia, reduced visual acuity, corneal haze/opacification

   • Causes: Infectious (bacterial, viral, fungal), contact lens misuse

   • Management: Urgent ophthalmic assessment (corneal scraping, topical antimicrobials)

3. Endophthalmitis

   • Presentation: Severe pain, red eye, marked vision loss, often post-surgery or trauma

   • Management: Emergency ophthalmology referral for intraocular antibiotics

Progressive Vision Loss

Progressive vision loss typically occurs over weeks to years, often due to chronic degenerative changes or systemic diseases impacting the eyes.

1. Refractive Errors (Myopia, Hyperopia, Astigmatism)

   • Presentation: Gradual blurring of vision, improved by prescription lenses

   • Management: Refraction test, corrective glasses or contact lenses

2. Cataracts

   • Symptoms: Gradual blurring, glare, difficulty with night driving, halos around lights

   • Risk Factors: Ageing, diabetes, steroid use, UV exposure

   • Management: Surgical lens extraction if functionally limiting

3. Age-Related Macular Degeneration (ARMD)

   • Dry (atrophic): Gradual central vision loss, drusen on fundoscopy

   • Wet (exudative): Sudden distortion or rapid deterioration of central vision due to choroidal neovascularisation

   • Management:

     • Dry: Antioxidant supplements, lifestyle modifications (smoking cessation), monitoring

     • Wet: Urgent referral for intravitreal anti-VEGF therapy

4. Chronic (Open-Angle) Glaucoma

   • Symptoms: Gradual peripheral vision loss → “tunnel vision”; often asymptomatic until advanced

   • Risk Factors: Raised intraocular pressure, family history, age >50, African or Asian heritage

   • Management: Intraocular pressure-lowering medications (topical prostaglandin analogues, beta-blockers), laser trabeculoplasty, or surgery

5. Diabetic Retinopathy

   • Presentation: Blurring in early stages; floaters or sudden vision loss if vitreous haemorrhage or retinal detachment

   • Management: Optimal glycaemic, BP, lipid control; regular ophthalmic review; laser or intravitreal therapy if proliferative changes

6. Other

   • Myopic Maculopathy: High myopia leads to macular thinning and degeneration → central vision loss

   • Retinitis Pigmentosa: Night blindness, progressive peripheral vision loss → tunnel vision

   • Optic Neuropathies (e.g. pituitary adenoma → bitemporal hemianopia): Gradual field defects; requires imaging

Key Features & Distinguishing Points

• Acute

  • CRAO: Sudden painless monocular loss, “cherry red spot”

  • CRVO: “Blood and thunder” fundus appearance

  • Retinal Detachment: “Curtain” over vision, flashes, floaters

  • Optic Neuritis: Pain on eye movement, colour desaturation

  • Acute Glaucoma: Severe pain, red eye, halos, mid-dilated pupil

• Progressive

  • Cataracts: Gradual blurring, glare, halos around lights

  • ARMD:

    • Dry → slow central loss

    • Wet → sudden distortion or rapid deterioration

  • Diabetic Retinopathy: May be asymptomatic early; risk of sudden loss if haemorrhage

  • Glaucoma: Gradual peripheral loss → tunnel vision

Practical Tips & Management Pathways

1. History & Exam

   • Onset: Sudden vs. gradual

   • Pain: Painful conditions (acute glaucoma, optic neuritis, corneal ulcer) vs. painless (CRAO, CRVO, detachment)

   • Associated symptoms: Headache/jaw claudication (GCA), flashes/floaters (retinal detachment), metamorphopsia (wet ARMD)

   • Visual Acuity Test: With and without pinhole (to exclude refractive error)

   • Fundoscopy: Essential for vascular occlusions, retinopathies, disc swelling

2. Immediate Actions

   • Suspected Retinal Detachment, CRAO, CRVO, GCA, or Acute Glaucoma → Urgent ophthalmology referral

   • High-dose corticosteroids if GCA is strongly suspected

   • Reduce IOP if acute angle-closure glaucoma

   • Stroke protocol if posterior circulation stroke suspected

3. Ongoing Management

   • Optimise systemic risk factors: BP, glucose, lipids

   • Lifestyle: Smoking cessation, UV eye protection, healthy diet (particularly for ARMD)

   • Follow-up: Regular eye checks for chronic conditions (e.g. diabetic retinopathy screening)