Test your field of vision
Anyone who notices a sudden movement out of the corner of his eye will snap his head around. This reflex lets us react to danger in good time. Test now to discover the range of your field of vision.
Important: Do not wear glasses for this test.
Cover your left eye with your free hand. Look straight ahead and keep looking in that direction while you move the pen slowly in an arc to the right with your outstretched arm.
Stop at the place where you pen disappears from your field of vision.
If you have a normal sized field of vision, your arm should be at a 90° angle from the starting point of the movement.
Carry out the same movement on the other side of your body until the pen disappears from your field of vision. The angle should be somewhat smaller, approximately 60°, because your nose limits your field of vision on that side.
If you have the impression that you don't reach the given angle, they you should definitely see an ophthalmologist.