There have been studies showing that eye-showers get infected with germs, if the water is not exchanged frequently. Also germs which may develop an inflammation of the eye conjunctiva have been detected. Please consider that in case of an accident infected water is released to an injured eye!
According to § 7.2 of the BGI/GUV-I 850-0 eye-showers have to be checked at least once a month. This includes putting the eye-shower into operation. Rinse with plenty of water.
Do not take eye-showers as a sacred object which may only be grabbed in case of an accident. On the contrary it is much better to use the eye-shower more often than once a month. According to § 7.2 of the BGI/GUV-I 850-0 you are even legally authorized to do so.
The only thing which you have to ensure is that the eye-shower remains clean. A calcified spray head is also not OK.
You should put the eye-shower at least once a week into operation. Take this opportunity to check inconspicuosly spray width and calcification.