Bluewater Health expects to reopen the Pat Mailloux Eye Centre at Petrolia's CEE hospital September 20.
The centre has been closed since the first week of August after a small number of fruit flies were discovered near a window sill in one of the procedure rooms.
VP of Operations Laurie Zimmer says staff conducted a thorough cleaning and undertook pest control measures during their investigation.
"Through the investigation we were not able to uncover any type of source," says Zimmer.
During the closure they've done some upgrades to hopefully prevent it from happening again.
Zimmer says work was done to seal the main doors and entrance into the procedure room, the walls and ceiling were also sealed to prevent any opportunity of external entry.
All scheduled procedures will continue to be performed in Sarnia, where about 150 patients have been accommodated so far.
Zimmer says this has been a significant closure for the hospital to manage and they apologize again for any inconvenience for patients and their families.
