1. Is to assess the efficacy of preoperative disinfection with chlorohexidine and povidone iodine in different concentrations separately .
2. Is to compare the efficacy of chlorohexidine to povidone iodine.
3. Compare patient comfort after instillation of each disinfectant .
4. To find which disinfectant is more effective tolerated and more safe for use .

Methods: This is a single center prospective study comparing antiseptic efficacy and ocular surface irritation with PI (povidine iodine) and AC (aqueous chlorhexidine). . Prior to sugery patients who meet inclusion criteria will be identified and informed consent will be obtained. Study personnel will obtain two samples one from conjunctival sac and th other from skin around the eye. Topical antisepsis will then be applied, the first eye will be randomized to one drop of either PI 5% - 2.5% or AC 0.1%- 0.05% and the second eye will receive the other agent. One minute after instillation of the eye drop to each eye, patients will rate their pain in each eye using the Wong-Baker (smiley face) rating scale. After 15 minutes the second swabs will be taken in the same manner as the first swabs. . On post-operative day three, study personnel will meet the patient and ask to rate the pain in each eye using the same verbal numerical rating scale and to perform slit lamb examination for any complication.

Inclusion Criteria:

• Current patient of the Assiute University Hospital arranged for ophthamic surgery
• Age greater than 12.

Exclusion Criteria:

• Documented allergy to PI or AC
• Current diagnosis of infectious keratitis
• History of unilateral contact lens wear in the past 30 days
• Current unilateral use of prescription eye drops.

The participant will be masked to which drug they receive, the investigator performing the analysis will also be masked