As an eye doctor, diagnosing a red eye can be challenging. Are we dealing with an infection, allergy, inflammation or dryness?

One of the most common questions I get is, “Doc, my eyes are red, burning, itchy, and tearing. Is this dry eye or from allergies?” The short answer is it could be one, both, or neither. I’ll outline various ways these conditions present clinically and the treatments for them.

The hallmark symptom of allergy – meaning if you have this symptom you almost definitely have the condition – is itching. Red, watery, ITCHY eyes are almost invariably due to an allergen, whether environmental or medicinal. It is one of the most common ocular conditions we, as...

Demodex  folliculorum -- often just called demodex -- is a mite that occurs naturally on many people's faces and resides in hair follicles, particularly the follicles of eyelashes. Most of the time, these mites cause no problems whatsoever. However, sometimes an infestation can become particularly parasitic, resulting in unhealthy eyelid margins and leading to problems.  Those problems as a group are called blepharitis.  Blepharitis can be caused by caused by several things, including allergies, bacterial overgrowth, Rosacea and also by demodex.

Often, diagnosis of mite infestation by your eye doctor can be difficult.  The symptoms can mimic other causes of blepharitis, which...