Does an optometrist's eye exam equipment, ever need calibration?

All optical equipment needs regular maintenance and cleaning. Most of the issues I've seen with this type of equipment has to do with the phoroptor, the device that they check your vision with. Little kids poke their fingers in the lenses and cloud them up. When the DR asks, "better one or two" and one of the lenses is dirty, what is he actually testing?

Other devies have have electronic calibration built in, they are a bit more maintenance free.

Of course it does. Its no different than a 'blood pressure" reading device, or a "heart monitor". Hundreds, if not thousands of people die every year because of faulty equipment readings.

certain equipment like a slit lamp or monocular ophthalmoscope may need to be focussed beforehand everytime they are used.