Eye squeeze is an effect which usually happens along with what is known by divers as mask squeeze. Mask squeeze can produce different symptoms and effects, but what is called as eye squeeze is the most usual one. Although most of the times this doesn’t cause a serious problem, it is very usual that it happens and it is interesting to learn why it does.
The air contained in the space within your face and your mask must have a pressure equal to the blood pressure of the face. If this doesn’t happen, and the mask air pressure is unequal to the blood one, this would cause the diver to suffer an eye squeeze. Our physical pressure should be equalized with the pressure of the exterior and it is important that we know how to maintain it.
Eye squeeze causes divers to have a reddish spot of blood in the white of their eyes. Sometimes finding this in their eyes scares divers, but usually it is not dangerous and looks worse than what it actually is. Even when it usually is not dangerous, it is always advisable that a diver who finds this red spot in their eyes consults with a physician about it.
One of the ways in which this problem can be avoided is by learning how to breathe properly in order to maintain the balance the mask air pressure and the facial blood one. If you exhale air through your nose, this will add air to the mask space, and therefore the air amount and pressure would vary causing a loss of balance. Therefore, divers should avoid exhaling through their nose or, otherwise, this could cause them to suffer an eye squeeze.
Besides the reddish spot in the white of the eye, this problem known as mask squeeze can cause other effects as well. Among some other things which might happen due to this pressure variation, a diver can suffer an injury in some of his facial tissues or in the skin area located around the eyes. These effects might show their symptoms by producing a variation in the color of the area, such as turning it into a red color or causing it to be bruised.
Source: Dive Pilot