Watering or tearing may occur in one eye or both eyes, depending on the cause of the condition. In some people, though, a condition exists in only one eye, but both eyes will tear in response. If a person does not notice gradual improvement in tearing or comfort, she should contact her eye doctor for an appointment. However, understanding some of the causes may help determine treatments to try when tearing initially begins.
A scratch on the cornea, the sensitive front layer of the eye, may cause tearing in the eye. The scratch, often referred to as an abrasion, may cause other symptoms as well. These can include pain, light sensitivity or redness, states MedlinePlus. Some abrasions result from a foreign body in the eye, such as dirt or plant matter. On occasion, the foreign body may adhere to the eye and require an eye doctor to remove the particle. If the foreign body does not stay in the eye, a person may try using artificial tears to keep the abrasion lubricated and as comfortable as possible. As the site heals, comfort and tearing should improve.
Eye allergies often cause eye tearing. This response occurs when the body's immune system overreacts to outside allergens, such as pollen, which causes tearing, irritation and redness, explains The University of Michigan Kellogg Eye Center. Tearing in one eye may result from a contact allergy, such as petting a dog or cat, then rubbing the eye. Allergy eye drops may offer relief from these symptoms. Over-the-counter allergy drops may offer relief, though some people may require a prescription-strength eye drop. Oral antihistamines or allergy medications may improve eye symptoms.
If a person has an eye infection, such as conjunctivitis, commonly known as pinkeye, he may experience tearing in one eye. Other symptoms may include itching, irritation and redness, states MayoClinic.com. Some people with severe symptoms may require an eye drop to help resolve the infection or treat the symptoms. In mild cases, conjunctivitis will gradually resolve on its own. Some people may find relief of symptoms by using cool compresses on the eyes. If tearing or other symptoms appear in only one eye, take care not to contaminate the uninfected eye.