What causes pressure over the left eye?

Pressure Over the Left Eye: Differential Diagnosis and Evaluation

Pressure over the left eye is most commonly caused by non-ophthalmic conditions including migraine, tension headache, or sinus disease, but requires systematic evaluation to exclude sight-threatening conditions like acute angle-closure glaucoma, which presents with severe ocular pain, elevated intraocular pressure, and a red eye. 1

Primary Ophthalmic Causes to Rule Out

Acute Angle-Closure Glaucoma

• This is the most critical ophthalmic emergency to exclude, presenting with severe ocular pain, headache, nausea, vomiting, blurred vision, halos around lights, and a red eye with a mid-dilated unreactive pupil. 1
• Requires immediate measurement of intraocular pressure and slit-lamp examination to assess the anterior chamber angle. 2
• If confirmed, immediate treatment includes topical beta-blockers, alpha-2 agonists, carbonic anhydrase inhibitors (like brinzolamide), and hyperosmotic agents, followed by definitive laser peripheral iridotomy. 2

Intermittent Angle-Closure

• Can cause periocular pain without obvious redness, making diagnosis challenging. 1
• Patients may experience episodes of pressure or pain that resolve spontaneously when the pupil constricts. 1

Low-Grade Intraocular Inflammation

• Uveitis or iritis can cause ocular pain without prominent external redness. 1
• Requires slit-lamp examination to identify anterior chamber cells and flare. 1

Vascular and Migraine-Related Causes

Migraine Headache

• Migraine is significantly associated with ocular pressure sensations and is more prevalent in patients with glaucoma (particularly normal-tension glaucoma at 28%) compared to controls (12%). 3
• Migraine decreases autoregulation of optic disc blood flow, which may contribute to the sensation of ocular pressure. 4, 5
• In "glaucoma suspect" patients with ocular hypertension, 51% experience attacks of mild to moderate "ocular pain" that are time-related to intraocular pressure changes. 6
• These patients often report ocular pain that is temporally associated with their migraine attacks. 6

Vascular Insufficiency

• Compromised optic nerve perfusion can manifest as periocular discomfort or pressure. 5, 7
• Low ocular perfusion pressure (the difference between blood pressure and IOP) is associated with glaucomatous damage and may cause symptoms. 4, 5
• Conditions like Raynaud's syndrome and peripheral vasospasm decrease autoregulation of optic disc blood flow and may contribute to ocular pressure sensations. 4, 5

Non-Ophthalmic Causes

Tension Headache

• Can present as pressure around the eye without associated visual symptoms or ocular findings. 3
• Prevalence in the general population is approximately 7%. 3

Sinus Disease

• Frontal or ethmoid sinusitis commonly causes pressure sensation over the eye. 1
• May be associated with nasal congestion, facial tenderness, and postnasal drainage. 1

Neurologic Causes

• Cluster headache presents with severe unilateral periocular pain, often with autonomic features like lacrimation and nasal congestion. 1
• Trigeminal neuralgia can cause sharp, lancinating pain in the distribution of the ophthalmic division. 1
• Cavernous sinus lesions, internal carotid dissection, or parasellar masses can cause periocular pain with or without diplopia and pupillary abnormalities. 1

Systematic Evaluation Approach

Initial Assessment

• Measure visual acuity to identify any vision loss that would suggest serious pathology. 1
• Examine the eye for redness: A red eye with pain suggests acute angle-closure glaucoma, uveitis, or scleritis requiring urgent evaluation. 1
• Measure intraocular pressure: Essential to rule out elevated IOP from angle-closure or other glaucomatous conditions. 8
  • Note that IOP measured in the first eye (whether right or left) tends to be higher than the fellow eye, so multiple measurements may be needed. 8

Detailed Ophthalmic Examination

• Pupillary examination: A mid-dilated, unreactive pupil suggests acute angle-closure; Horner's syndrome may indicate carotid dissection or cluster headache. 1
• Slit-lamp examination: Assess for corneal edema (angle-closure), anterior chamber inflammation (uveitis), and angle anatomy. 2
• Fundoscopic examination: Evaluate the optic nerve for signs of glaucomatous damage or papilledema. 4

When Ophthalmic Examination is Normal

• Obtain headache history: Characterize the pain pattern, duration, associated symptoms (photophobia, nausea, aura), and triggers. 3, 6
• Assess for migraine criteria: Unilateral location, pulsating quality, moderate-to-severe intensity, aggravation by routine physical activity, with nausea/vomiting or photophobia/phonophobia. 3
• Consider sinus evaluation: If symptoms suggest sinusitis (facial pressure, nasal symptoms, worse with bending forward). 1
• Neurologic examination: Assess for cranial nerve deficits, particularly if pain is severe, persistent, or associated with diplopia or neurologic symptoms. 1

Critical Pitfalls to Avoid

• Do not dismiss ocular pain without redness: Intermittent angle-closure, low-grade inflammation, and eyestrain can cause pain without obvious external signs. 1
• Do not rely on a single IOP measurement: IOP varies with measurement order and patient anxiety; multiple measurements at different times may be necessary. 8
• Do not overlook the migraine-glaucoma association: Patients with migraine, particularly women, have higher rates of ocular hypertension and may experience ocular pain related to IOP fluctuations. 6
• Do not miss temporal arteritis in older adults: New-onset headache with visual symptoms in patients over 50 requires immediate ESR/CRP and consideration of temporal artery biopsy. 1

When to Refer

• Immediate ophthalmology referral: Red eye with pain, elevated IOP, decreased vision, or suspected angle-closure. 2
• Urgent ophthalmology consultation: Persistent or recurrent ocular pain without clear diagnosis, particularly if IOP is borderline elevated or optic nerve appears abnormal. 4
• Neurology referral: If headache pattern suggests migraine or other primary headache disorder requiring specialized management, or if neurologic signs are present. 3