A sinus infection (sinusitis) can cause pain that feels located directly behind the eye. Sinusitis involves the inflammation of the tissue lining the paranasal sinuses, which are air-filled cavities within the bones of the face and skull. This inflammation leads to a buildup of mucus and increased pressure within these spaces. Pain behind the eye is a common symptom resulting from the close anatomical relationship between the sinuses and the eye socket structures.
The Anatomical Explanation for Referred Pain
The discomfort begins with increased pressure inside the sinus cavities. When the sinus linings swell due to infection, drainage pathways become blocked, trapping fluid and air. This pressure presses outward on the thin walls separating the sinuses from adjacent structures, including the eye socket.
Pain signals generated by this pressure are transmitted through the trigeminal nerve (Cranial Nerve V), which is responsible for sensation in the face. This nerve supplies branches to both the sinuses and the orbital region. When nerve endings in the inflamed sinuses are irritated, the brain sometimes misinterprets the pain’s origin.
This phenomenon is known as referred pain, where the brain perceives the sensation as coming from a different area of the body than the actual source. Because the same nerve pathway carries signals from both the sinuses and the tissues surrounding the eye, the pressure from the infection is perceived as a deep, aching pain located behind the eye itself. This neurological cross-talk explains why the pain can feel localized to the eye, even when the infection is centered in the nasal cavity region.
Identifying Key Sinuses Associated with Eye Pain
The location of the pain behind the eye is often determined by which specific sinus cavities are affected. The paranasal sinuses are four paired cavities, but the ethmoid and sphenoid sinuses are particularly close to the eye socket.
The ethmoid sinuses are small air cells located between the eyes, near the bridge of the nose. Inflammation here commonly causes pain felt in the inner corner of the eye and radiating behind it. Infection in these cells can quickly transmit pressure to the thin bone forming part of the orbital wall.
The sphenoid sinuses are situated deeper within the skull, behind the nasal cavity and directly beneath the pituitary gland. They are located just behind the eye and are in intimate contact with the optic nerve, which transmits visual information to the brain. Due to this deep and posterior location, an infection here is a common cause of pain described as being deep inside or behind the eye.
Recognizing Warning Signs and When to Seek Care
While pain behind the eye is a common symptom of sinusitis, certain changes in symptoms can signal that the infection may be spreading beyond the sinus cavity, requiring immediate medical attention. This spread can lead to serious complications, such as orbital cellulitis, an infection of the soft tissues within the eye socket. Distinguishing between typical sinus discomfort and these red flag symptoms is important.
Signs of a potentially dangerous complication include:
- Sudden changes in vision, such as blurriness, decreased visual acuity, or double vision (diplopia).
- The inability to move the eye normally or pain when attempting to move the eye can also indicate a spread of infection.
- Visible changes around the eye, such as bulging of the eyeball (proptosis).
- Significant redness and swelling of the eyelid that extends beyond the skin.
Other systemic signs, including a high fever, severe headache, confusion, or a general feeling of being very ill, should prompt an immediate evaluation by a healthcare provider. These symptoms suggest the infection may be impacting other nearby structures or spreading to the bloodstream. For a persistent, non-urgent sinus infection, medical care is recommended if symptoms last longer than 10 days, if they worsen after initially improving, or if you experience recurrent episodes.