Questions are being raised over the Southern District Health Board's culture, after ophthalmology delays saw 30 patients unnecessarily lose part of their sight over the past two years.

The under-pressure DHB is also writing to over 4500 more patients to say they could be affected by the delays.

Acting chief executive Chris Fleming said they are giving the eye care services a modest increase, after their initial increase wasn't enough to cope with demand.

"Demand for ophthalmology services have significantly increased and what I can say is, Southern DHB, we haven't adjusted the resourcing in a timely enough manner in order to stay on top of the challenges we're facing.

"We've already made commitments about increasing optometrists and ophthalmologists' resources. We're exploring options about extending nursing practice and we're also working with general practice around opportunities of advancing the skills in primary care."

Association of Salaried Medical Specialists director Ian Powell says it's a nationwide issue, but sticks out down south because of the DHB's dynamics.

"There has been a culture in that District Health Board of clinical disengagement. Not taking notice of clinical concerns being raised and addressing them in a timely manner. The voice of expertise is largely lost."

Mr Powell said more resources and a better view of workforce vulnerability are needed, to avoid similar situations in the future.

"The response to the increased patient needs has been to reduce the resourcing. Now that's an untenable mix and that's got to stop."

Minister of Health Jonathan Coleman says a new clinical prioritisation tool is about to be introduced.

"Where they can actually see the people with the highest need earliest, and that's going to be the key. Whereas at the moment there's some debate around who is being seen when."

Mr Coleman describes the situation as "clearly unacceptable."

"But clearly in Southern there's a issue which they need to address and that's why there's an independent review going on. HGSC has identified these 30 separate cases that need further follow ups so yes, they need to do better."