DEAR DOCTOR: Concerning the discussion of Maddox Rod vs. Phorometer
about which you wrote me—can say that I believe that the Maddox rod
is the more reliable test. My reasons on theoretical grounds for so
believing are briefly these.
Given a case for examination; the test which _least disturbs_ the
muscular co-ordination under investigation must give the best
result. Now I think that when we throw the images into
non-corresponding retinal points that we almost certainly cause some
tension of certain muscles, because it is putting the eyes in an
_unnatural_ relation with one another; and this is done by the
phorometer. The Maddox rod is theoretically free from this
objection.
_Practically_ the deviations are more certainly measured, because a
patient _knows_ when the streak cuts the light; and you cannot trust
their eye alone to tell when the lights are exactly in a line. Have
used _both_ tests in every case I have examined in my private
practice, and I find the Maddox the more reliable test. It is more
to be depended upon.