Irritation and Itching The most common cause is Allergic conjunctivitis if redness is also there, for which you require Anti Histamine eye drops or anti allergic drops or any anti-inflammatory eye drops. At times this can be self resolving without any medication. Gentamycin is a broad spectrum antibiotic which kills bacteria but doesn't decrease itching specifically. Most common Causes of Itching with irritation without redness are: - Dry eye ( decreased lubrication of eye) - Early Allergic conjunctivitis - Computer vision syndrome (UV light damages corneal epithelium) Feel free to follow up:) Hope it helps :)