An increase of patients needing treatment for chronic sight-threatening diseases has meant the Southern District Health Board (SDHB) has had to postpone more than 4600 appointments.
DHB Chief Medical Officer Dr Nigel Millar says the systems in place have struggled to cope with the demand.
"SDHB has seen a significant increase in the number of patients with chronic sight-threatening eye disease requiring assessment," he says.
"In recent years new treatments have become available - which have undoubtedly been positive for patients, as they offer possible benefits for conditions that were previously difficult to treat.
"However, they require frequent follow-up appointments.
"The SDHB's systems of care and treatment delivery in ophthalmology have struggled to keep up with this increase in demand."
Dr Millar adds the DHB has contacted and apologised to those patients whose eyesight has deteriorated during the period of the delay.
"We've written to all our ophthalmology patients who are overdue for appointments, apologising to them, and providing an explanation for this delay."
SDHB Interim chief executive Chris Fleming says waiting times for patients has increased dramatically.
"With the problem we've uncovered within our system, paitents have been waiting up to five times as long as they should be," he says.
"The majority of [waiting time] would be sort of three months to one year timeline.
"We fully acknowledge that we did not provide the follow-up care and treatment within the clinically recommended time frame, and sincerely apologise for this," he says.