A face mask creates an additional gas space external to, but in contact with, the face. Unless pressure is equalized by exhaling gas into the mask, facial tissues will be forced into this space during descent.
In some diving masks, such as with swim goggles, there is no way of equalizing the pressures during descent, so that facial barotrauma is almost inevitable with descent (limited to the eyes and surrounds, with goggles). Barotrauma is avoided in these situations by employing very flexible masks or adding flexible gas containers to the eye space.
Clinical features of mask barotrauma include puffy oedematous facial tissues especially around the eyes, purpuric haemorrhages, conjunctival haemorrhages, orbital haemorrhages and haematoma and generalized bruising of the skin underlying the mask (Figure 9.2 and Plate 2).
This condition is rarely serious, although orbital haemorrhage may be. Prevention involves exhaling into the face mask during descent. Treatment involves avoidance of diving until all tissue damage is healed.