240 Floating Specks: Their Cause and Cure
their eyes were normal, but I did not know how to re lieve them of the symptom, which is simply an illusion resulting from mental strain. The specks are associated to a considerable extent with markedly imperfect eye sight, because persons whose eyesight is imperfect al ways strain to see; but persons whose eyesight is ordi narily normal may see them at times, because no eye has normal sight all the time. Most people can see muscae volitantes when they look at the sun, or any uniformly bright surface, like a sheet of white paper upon which the sun is shining. This is because most people strain when they look at surfaces of this kind. The specks are never seen, in short, except when the eyes and mind are under a strain, and they always disappear when the strain is relieved. If one can remember a small letter on the Snellen test card by central fixation, the specks will im mediately disappear, or cease to move; but if one tries to remember two or more letters equally well at one time, they will reappear and move.
Usually the strain that causes muscae volitantes is very easily relieved. A school teacher who had been annoyed by these appearances for years came to me be cause the condition had grown recently much worse. I was able in half an hour to improve her sight, which had been slightly myopic, to normal, whereupon the specks disappeared. Next day they came back, but another visit to the office brought relief. After that the patient was able to carry out the treatment at home, and had no more trouble.
A physician who suffered constantly from headaches and muscae volitantes was able to read only 20/70 when he looked at the Snellen test card, while the retinoscope showed mixed astigmatism and he saw the specks.