What device is used in a field protective mask for Marines that wear glasses?

In a field protective mask for Marines who wear glasses, optical inserts are specifically designed to accommodate prescription eyewear. These inserts allow a Marine to maintain clear vision while still receiving the necessary protection that the mask provides, ensuring both safety and operational effectiveness.

Using optical inserts is crucial because standard masks do not fit over traditional glasses, which could compromise the seal and effectiveness of the mask against chemical, biological, radiological, or nuclear threats. Optical inserts are custom-fitted to the individual Marine's prescription and are placed directly into the mask, allowing for comfort and proper alignment with the eye position within the mask.

While contact lenses could be an alternative for some Marines, they may not be suitable in all field conditions, especially where there might be exposure to chemical agents. Face shields and prescription masks do not provide the same level of integration into the established protective systems as optical inserts do, making them less effective options in this context.