The new unit at Pinderfields Hospital, which will be opened this afternoon by Wakefield MP Mary Creagh, will treat patients with eye problems like macular degeneration, glaucoma and cataracts.
The unit, which started treating patients in April, will free up space at Pinderfields for around 90 new beds to cope with extra patients after A&E services are centralised at the hospital.
Under a re-organisation of services, Dewsbury and District Hospital will no longer have a consultant-led A&E department.
And critically-ill and injured patients will be transferred to a centralised A&E department at Pinderfields.
Dewsbury will also lose its consultant-led maternity unit as complex births are transferred to Pinderfields.
Mid Yorkshire has also announced that building work on a new birthing centre at Dewsbury Hospital will start in October and it is expected to open in May next year.
The plans mean that the hospital’s obstetric doctors will move to the labour ward at Pinderfields Hospital.
Last month the coronary care unit at Dewsbury hospital was closed under the Meeting the Challenge programme to restructure services.
Previously, people who arrived at A&E with conditions like heart attacks or very slow or fast heart beats were taken to the unit. They are now transferred on the same day to Pinderfields.
Mid Yorkshire said the move would speed up care because patients would no longer be admitted to Dewsbury, then transferred to Pinderfields for procedures.
People with the most serious heart conditions are taken straight to Leeds General Infirmary.