If it is, open both eyes, then close the other eye. Remember with which eye you saw the object. That is your dominant eye. The other eye is not working as hard as your dominant one. The Accommodation-Convergence Exercise on page 33 of Secrets of Seeing Without Glasses or Contacts Book is designed to build your eyes into an equally strong team where you see objects with both of your eyes rather than with one.
Some people actually turn their heads using the dominant eye side to see.
It would reduce the strain on the dominant eye for you to build the strength in the weak eye so that it becomes an equal partner in the business of seeing.