Patients were outraged after it emerged a laptop containing 1,100 personal files had been stolen from a hospital.
The computer disappeared from a consultation room in the Ophthalmology department of Peterborough District Hospital between 26 and 27 April.
It contained the retinal images, names and hospital numbers of patients who had recently undergone eye examinations.
A red-faced hospital spokesman revealed the patient details were not encrypted or password protected.
The hospital only publicly revealed the theft after first informing the patients concerned.
Nik Patten, chief executive of Peterborough and Stamford Hospital Trust, admitted security measures on the laptop had been lax.
He said: ”Unfortunately the laptop contained the names and hospital numbers of around 1,100 patients who recently had eye examinations, as well as their retinal images.
”All patient information contained on the trust’s IT network is encrypted and password protected, however on this occasion the data held on this standalone laptop was not.
”The database of patients’ names was temporarily stored on the laptop’s hard drive while work was being carried out to connect the laptop to the Trust’s IT network enabling it to be protected by the Trust’s usual security measures.”
A spokeswoman from Cambridgeshire police appealed for witnesses who may have seen any suspicious activity at the hospital to come forward.
She said: ”There is an on-going investigation into the matter and we are appealing to anyone with information about the theft to contact us.”