The face shields provide an additional barrier protecting the face and neck in addition to the eyes. Also in the issue rooms and research labs free standing plastic shields are available. The shield is placed in front of the chemical apparatus and is narrow enough that you can wrap your arms around the shields to make adjustments in the equipment or start the reaction. Wearing contact lenses in the lab is acceptable and does not create an additional hazard for the wearer. However, appropriate safety goggles must be worn.
Some soft lenses do absorb organic vapors and corrosive vapors like hydrogen chloride or ammonia.
So if you are wearing contact lenses and notice any discomfort while working with volatile solvents, or corrosive liquids or gases then the lenses should be taken out.