What causes seeing halos around objects and how is it treated?

Seeing Halos Around Objects: Causes and Treatment

Halos around lights are most commonly a warning sign of acute angle-closure glaucoma requiring emergency evaluation, but can also indicate cataracts, corneal edema, refractive surgery complications, or corneal ectasia—immediate assessment is essential to rule out sight-threatening angle-closure. 1, 2, 3

Emergency vs Non-Emergency Differentiation

The initial priority is determining whether this represents an acute angle-closure crisis, which can cause permanent vision loss within hours if untreated. 3

Red flag symptoms requiring immediate ophthalmologic evaluation include: 1, 3

• Eye pain or severe headache
• Eye redness
• Nausea and vomiting
• Sudden vision loss
• Mid-dilated pupil

If these symptoms are present, this is acute angle-closure glaucoma until proven otherwise. 3

Primary Causes of Halos

Angle-Closure Glaucoma (Most Urgent)

Intermittent angle-closure presents with the pathognomonic combination of bilateral halos, transient blurred vision, and self-resolving episodes. 2 The halos result from pressure-induced corneal edema when intraocular pressure rises during angle-closure episodes. 1, 2, 3

Critical risk factors include: 3

• Asian or Inuit ethnicity
• Female gender
• Age over 50 years
• Hyperopia (farsightedness)
• Shallow anterior chamber depth
• Family history of angle-closure glaucoma

Untreated intermittent angle-closure carries a 50% risk of progressing to acute crisis within 5 years, and 18% of eyes become blind within 4-10 years following untreated acute attacks. 2, 3

Cataracts

Different cataract types cause halos around lights, particularly noticeable when driving at night. 1 Posterior subcapsular cataracts specifically cause glare and poor vision in bright light conditions. 1

Post-Refractive Surgery Complications

Patients with prior LASIK, PRK, or SMILE surgery may develop halos from irregular astigmatism or corneal ectasia. 1 Smaller treatment-zone sizes increase the likelihood of visually disturbing halo formation in low-light conditions. 1

Corneal Ectasia

Keratoconus and other ectatic disorders cause glare, halos, multiple images, ghosting, and reduced visual acuity. 4 These conditions typically present in the second or third decade of life and are often progressive. 4

Essential Evaluation Components

Key history elements: 1, 2

• Duration and progression of symptoms
• Presence of pain, redness, nausea, or vision loss
• History of refractive surgery
• Family history of glaucoma
• Timing of symptoms (worse at night, with pupil dilation)

Physical examination must include: 1, 3

• Visual acuity assessment
• Intraocular pressure measurement
• Pupil examination (mid-dilated pupil suggests acute angle-closure)
• Slit-lamp examination for corneal edema, lens opacities, and anterior chamber depth
• Gonioscopy to assess the iridocorneal angle and detect angle closure 2, 3

Treatment Algorithms

For Acute Angle-Closure Crisis

Immediate medical therapy to lower intraocular pressure: 3

• Topical beta-blockers
• Topical alpha2-agonists
• Topical carbonic anhydrase inhibitors
• Oral or intravenous hyperosmotic agents

Definitive treatment once pressure is controlled: 3

• Laser peripheral iridotomy (LPI) in the affected eye
• Prophylactic LPI in the fellow eye (acute attacks can occur within days)
• Verify iridotomy patency after procedure

For Intermittent Angle-Closure

Laser peripheral iridotomy is the definitive treatment once gonioscopy confirms iridotrabecular contact. 2 Both eyes require treatment given the bilateral nature of primary angle-closure disease. 2

For Cataracts

Regular monitoring for progression with consideration of cataract surgery when visual function is significantly affected. 1

For Post-Refractive Surgery Halos

Evaluation for irregular astigmatism or corneal ectasia, with management options including specialty contact lenses, corneal cross-linking for progressive ectasia, or enhancement procedures in select cases. 1

For Corneal Ectasia

Early detection and prompt treatment with corneal cross-linking can reduce or stop keratoconus progression and preserve good visual acuity with eyeglasses or contact lenses. 4

Critical Pitfalls to Avoid

Do not dismiss transient symptoms as benign, even if the patient is asymptomatic at presentation—these represent warning episodes before potentially blinding acute attacks. 2

Avoid pupil dilation until after angle-closure is ruled out or iridotomy is performed, as dilation can precipitate acute angle-closure crisis in patients with occludable angles. 2

Do not delay fellow eye prophylaxis after treating one eye for angle-closure, as acute attacks can occur within days. 2

Monitor for persistent intraocular pressure elevation after laser peripheral iridotomy, as some patients may have plateau iris configuration that persists after iridotomy. 3