A small amount of chemical, when quickly washed off shouldn t cause any harm. A much stronger amount of it will. Any such things should be kept out of reach of children young enough not to understand the purpose of chemistry and to listen to safety instructions. Goggles and aprons should be used to protect eyes and clothes. In some cases, regular goggles are not enough for contact lenses wearers.
Chemicals can sometimes get in through the sides of the goggles in into the contact lenses.
In the case that contacts must be worn, a style of goggles called eye cup may be worn. Sometimes it is also wise to wear gloves, depending on the tools that will be used. Fume hoods are sometimes necessary when working with chemicals. Well-ventilated areas should be used no matter what kind of chemicals are being used, just in case. In case of emergency in any of these cases, if chemicals are spilled, gotten in eyes, etc.