VI. Diphtheria and Influenza—Crossed Eyes

Now, you see, the optic nerves are such that when the head is viewed from above, they proceed back from the eyes. They cross in the brain, the two optic nerves, and continue on to the hindbrain. The optic nerves must be in good condition if we are to see well, because we see with both eyes. The moment these optic nerves that cross are not working properly, we see double. The optic nerves only need to be a little numbed and the crossing not made properly for us to see double. You know how a person who enjoys drinking can tell whether or not he is still functioning when he gets home: he places his hat at the foot of the bed, gets in bed, and if he sees one hat he is still all right, but if he sees two, he is not! This is easily done. So, because the blood circulates too fast, too much alcohol numbs the optic nerves, with the result that a person who has drunk too much has double vision.