Gas masks posed a dilemma for soldiers wearing eyeglasses. The first gas masks were essentially flannel bags with mica lenses. The fit over glasses was often a problem. In addition, glasses tended to fog underneath these hoods.
The soldier had the choice between fighting blind or being gassed. Fortunately, early in the Great War, conscripts who wore spectacles were seldom considered fit enough to send to the front. This changed later in the war.
The hoods were phased out in favor of small box respirator gas masks but these were so tight eyeglass frames worn underneath could compromise the gas mask’s flushness of fit and protection.
The Axis powers were outnumbered and by 1917 had higher casualty rates than the Allies. All able bodies were needed. Eyeglasses were no longer an obstacle to service at the front. Germany was first to develop eyeglasses that could be worn with gas masks: the maskenbrille,
Instead of traditional wire temples these glasses came with fabric loops that could be wrapped around the ears.