Hi. Thanks for your query. You have quite an unique query as such cases of having severe sneezing on removal of the oxygen canula are not heard of. Yet to have a logical explanation, the possibilities are : - You already had allergic rhinitis which got instigated due to changed atmosphere. - There may be siomething in the recovery room, some smell, fumes or so that caused this problem. - The canula must have touched the inside of the nasal mucosa instigating sneezing. In such a case claritine alone may not help. Hence you should take steroidal nasal spray and a shot of steroid orally or by injection since sneezing can cause failure of the cataract surgery. Short course of steroid causes no problem in healing.