What are the causes of foreign body sensation?


"A foreign body or gritty sensation in the eye is a frequent reason for a visit to the eye doctor. It may be accompanied by red eye, watering eyes, photophobia, pain, burning or stinging, etc."

The cornea is the most sensitive part of the whole body. It is approximately 400 times more sensitive than the skin. That’s why something as minuscule as an eyelash can cause great discomfort if it falls in the eye yet we’d hardly notice it if it fell on our cheek.

The causes of this symptomology are varied and are often due to a small foreign body entering the eye, such as an eyelash, particles of pollen (in spring), sand from the beach (in summer), make-up remnants, etc.  

However, there are other causes as listed below:

1. Inflammation of the conjunctiva (called conjunctivitis). Types include allergic, viral, bacterial, or mechanic. A sty may also cause this sensation since the bulge causes mechanical friction in the eye.

2. Overuse of contact lenses among young people, causing an allergic reaction in the conjunctiva or a cornea infection. 

3. Dry eye syndrome due to a lack of tears or poor quality thereof, particularly when we overuse screens, computers, or mobile phones. 

4. Blepharitis patients (inflammation of the eyelid margin and eyelashes) usually complain of a foreign body sensation in the morning when they get up. 

5. With severe dry eye, a foreign body sensation fluctuates with the level of eye hydration. 

6. In patients that have once had a cornea injury, due to weak adhesion of the surface skin of the cornea (epithelium) they may notice heightened pain and a foreign body sensation in the morning. Recurrent corneal erosion may occur months or even years after a corneal injury.

When a foreign body enters the eye because of an accident, it’s essential to go to A&E to assess whether eye tissue has ruptured, to remove the foreign body and have appropriate medication prescribed to prevent infections. In any case, careful cleaning with saline solution, hydration of the body, and the eyes with artificial eyedrops, the use of protective glasses and a healthy diet always help to maintain healthy eyes and keep these eye pathologies at bay. 

Dr. Maria de la Paz, ophthalmologist at the Barraquer Ophthalmology Center