asked Her Majesty's Government:
Further to their Answer in the House on 29th January 1996 [H.L. Deb., col. 1232], what information they have on accidents being caused by motorists' glasses falling off or their contact lenses coming out.38WA
§ Viscount Goschen
We are not aware of any information that would show a causal link between glasses falling off or contact lenses coming out and accidents. The practical reason for requiring lorry and bus drivers to meet an uncorrected eyesight test is not that such mishaps may cause accidents, but that, in an accident or emergency, glasses or contact lenses may be dislodged, so that the driver has to halt the vehicle or manoeuvre it to safety without their benefit.