The sensation of pressure behind the left eye can arise from structures within the eye socket or from referred pain originating elsewhere in the head and face. The region behind the eye is densely packed with nerves, sinuses, and blood vessels, and this feeling can range from a dull ache to intense pain. Self-diagnosing the cause of this discomfort is dangerous, as the symptom can be a sign of conditions requiring immediate medical or ophthalmic consultation. A healthcare professional is necessary to determine the underlying cause, which may involve the ocular, neurological, or sinus systems.
Ocular Conditions Causing Posterior Pressure
Pressure felt directly behind the eye can indicate issues with the eye structure itself or the optic nerve. One common, benign cause is simple eye strain, often related to uncorrected refractive errors or prolonged focus on digital screens. This discomfort results from fatigue in the muscles responsible for focusing and moving the eye, leading to a dull ache that typically resolves with rest.
A more serious condition is acute angle-closure glaucoma, which constitutes a medical emergency. This occurs when the eye’s natural drainage angle is suddenly blocked, causing a rapid increase in intraocular pressure. The intense pressure is accompanied by severe eye pain, blurred vision, seeing halos around lights, nausea, and vomiting.
Inflammation of the optic nerve (optic neuritis) frequently causes pain behind the eye that worsens with movement. This involves swelling and damage of the nerve, often leading to temporary vision loss and reduced visual acuity. Another inflammatory cause is orbital pseudotumor, where non-cancerous swelling occurs in the tissues behind the eyeball, sometimes restricting eye movement.
Sinus and Facial Structure Involvement
The feeling of pressure behind the eye often originates from the air-filled cavities within the skull known as the sinuses. Sinusitis, the inflammation and swelling of these cavities, can create referred pain due to their close proximity to the eye socket. The ethmoid sinuses (between the eyes) and the sphenoid sinuses (deeper behind the eyes) are common sources of this posterior pressure.
When these sinuses become congested with fluid and mucus due to infection or allergies, the resulting pressure transmits a sensation of fullness or pain behind the eyes. Frontal sinusitis, which affects the sinuses above the eyes, also contributes to a feeling of heaviness or pressure that radiates downward. This pain often intensifies when a person bends over or moves their head suddenly.
Referred pain from dental or jaw issues can also manifest as pressure behind the eye, due to shared nerve pathways. An infection or abscess in an upper molar, for instance, can irritate the branches of the trigeminal nerve that supply both the teeth and the eye area. Similarly, dysfunction of the temporomandibular joint (TMJ) can cause tension and muscle spasms that radiate pain into the temple and around the eye socket.
Primary Headache Disorders
Several primary headache disorders are characterized by pain or pressure concentrated behind one eye. Migraines are a common cause, often presenting with unilateral, throbbing pain localized to the area around or behind the eye. This pain is mediated by the trigeminal nerve system, which becomes activated during a migraine attack, sending pain signals via nerve endings that innervate the eye socket.
A specific and severe form of head pain is the cluster headache, described as an excruciating, sharp, or stabbing sensation behind one eye. These attacks occur in cyclical periods and are accompanied by autonomic symptoms on the same side as the pain. These symptoms include a drooping eyelid, tearing, redness, and nasal congestion or a runny nose.
While less specific, tension headaches can sometimes localize as pressure or a dull ache behind one eye, though they more commonly affect both sides of the head. The intensity and secondary symptoms of migraines and cluster headaches usually distinguish them from the generalized pain of a tension headache. Unilateral migraine pain may also be associated with temporary visual disturbances like flashing lights or blind spots.
Vascular and Neurological Considerations
Unilateral pressure or pain behind the eye can signal a serious underlying vascular or neurological event requiring immediate investigation. Giant Cell Arteritis (GCA), also known as temporal arteritis, is a form of vasculitis that affects the arteries in the head. This condition is a concern in people over 50 and can lead to sudden, irreversible vision loss if not promptly treated. Associated symptoms often include a new, persistent headache near the temple, jaw pain while chewing, and scalp tenderness.
Another acute vascular cause is a carotid artery dissection, which involves a tear in the wall of the artery in the neck. This condition presents with sudden, severe pain in the head, neck, or behind the eye on one side, and may be accompanied by a drooping eyelid or other neurological signs. These symptoms result from the disruption of blood flow or irritation of surrounding nerves.
Constant, worsening pressure may rarely be a sign of a space-occupying lesion, such as an unruptured intracranial aneurysm or a tumor. An aneurysm, a bulge in a weakened blood vessel wall, can press on nearby cranial nerves, causing pain behind the eye, a dilated pupil, or double vision. These neurological causes, while uncommon, require urgent assessment to prevent life-threatening complications.