Brief Answer:
different possible causes

Detailed Answer:
HI, thanks for using healthcare magic

Unilateral redness and discomfort of the eye is most commonly due to : (1) infection either viral or bacterial. Viral is more common. If there is a purulent (pus like) discharge then more likely bacterial

Viral infection is usually self limited, lasting only a few days (up to a week). Eye hygiene (cleaning the discharge when present), is the main treatment.

Bacterial infection would require antibiotic eye drops.

(2)dry eye- treated with artificial tears

(3)subconjunctival hemorrhage - this would cause a very red discoloration in most cases

It resolves on its own

(4)episcleritis- this is a self limiting (goes on its own) inflammation or irritation of the eye, most persons do not require any treatment
If it is severe then artificial tears and steroid drops may be needed

(5)foreign object or trauma to the eye

(6)allergies- usually though affects both eyes and associated with itching. If present then using an anti histamine may help

There are more severe causes of redness but these are most commonly associated with severe pain which you do not have at the moment.

If there is no history of trauma or discharge then may be episcleritis , dry eye or hemorrhage, using artificial tears would help with the first two.

If there is any watery discharge then this may indicate viral infection is most likely

If there is a purulent discharge then a bacterial infection may be present and anti biotic drops may be needed.

You may need to be assessed.

I hope this helps, feel free to ask any other questions

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