Emergency medicine and surgery group manager Dr Colleen Coop said it was a matter of finite resources versus infinite demand.
The hospital was planning to carry out about 500 procedures this year, about the same number as last year.
The threshold for the surgery had been increased by five points on the clinical priority assessment criteria (CPAC) scoring system.
The information used for this is compiled by the consultant assessing the patient and allocating scores and also the patient filling out a social score about how they are affected by their condition.
The points now need to add up to 55 to qualify.
Some people visually unfit to drive may have a long wait before surgery, but Dr Coop said not being fit to drive was not a sole factor which would qualify a patient for surgery.
Limited capacity and resources meant patients regarded as having non urgent or routine conditions would be returned to the care of their family doctor. (The doctor would monitor the condition and refer the patient again if it was considered the situation had worsened to the stage of meeting the criteria.)
This had been happening for at least the last three years, she said.
A patient who contacted the Otago Daily Times expressed concern that as the eyesight of a patient in this situationdeteriorated further they were in danger of having falls, which could be much more expensive to both the patient and the health system. It seemed an unreasonable risk when cataract surgery was usually a relatively simple procedure which only took about 20 minutes.
He said he could not afford to have private surgery, which he understood would cost about $5000, and faced an uncertain waiting time for surgery, even though he was legally unable to drive.
Dr Coop said what had also compounded the situation was the introduction of a service for vitreoretinal surgery (known as VR and including surgery for such conditions as retinal detachment). Such patients had previously been seen in Christchurch.
This service was still in the setting-up phase, and initially would be getting through "a hump of patients awaiting this surgery since the start of the year", affecting the slots available for other patients. It was expected this would be temporary.
Dr Coop said patients who were already in the hospital's system and approved for surgery when the points threshold was raised were not affected by the increases as they had already been given certainty about their operations.
