Vision through various scuba facemasks.

The visual performance of divers was compared utilizing five commercial facemasks. Measurements were made of visual fields, visual acuity, stereoacuity, hand-eye coordination, accuracy of distance estimates, and accuracy of size estimates at both near and far distances. In addition, the optical properties of the masks were measured and the susceptibility of each mask to fogging was tested. There were significant differences between the masks for every visual process tested. Some masks were superior for one purpose, and inferior for another purpose. For example, the compensating mask improved size and distance estimates and hand-eye coordination but degraded acuity and stereoacuity. In every test, the results for the goggles fell between those for the compensating mask and those for the other three masks. The results were not explained on the basis of susceptibility to fogging.