A study of the post-operative course in 100 patients subjected to cataract extraction revealed fairly pronounced dehydration of the corneal epithelium and the generally non-exposed segment of the conjunctiva, estimated by Rose Bengal stainability. This dehydration was to become appreciably reduced from the first to the third post-operative day, reaching normal levels of Rose Bengal stainability. The exposed conjunctival segment showed a surprisingly low Rose Bengal stainability on the first post-operative day, in 10% declining until the third day. Disinfection with polyvinylpyrrolidine iodide was found not to alter the stainability of cornea and conjunctiva, compared with the commonly employed method of disinfection with tincture of iodine. In 34% 'bulla'-like formations localized in the superior half of the cornea were noticed on the first post-operative day. These were supposed to represent oedema. The percentage had declined to 20 on the third day.