A perimeter

This old object for visual research had been forsaken to a cupboard for tens of years, I suppose. It was full of dust and now it gets it's publicity for a moment , before it is again forsaken to a black cupboard for undetermined time.

I asked an explanation from our retired professor Veijo, who is a prominent researcher of visual psychology. Here is his thoroughful explanation and I put it as such.


"The device in your picture is a perimeter used for measuring the outer
limits of vision in each eye of subject's visual field. For example,
for the right eye, the subject's kin is placed on the left pit. Then
the height of the rod in the middle is adjusted so that the pupil of
the right eye is at the level of its small pit. The left eye is covered.

After this the experimenter begins to move some stimulus object from
the center of the arc (0 degrees) towards its perimeter. He records
the number of degrees, at which the subject cannot see the stimulus
object any longer. This is repeated starting from the outer limit of
the arc (90 degrees).

By rotating the arc, this number of degrees is recorded for various
rotation angles (full circle) so that the outer limits of seeing the
stimulus object by this eye are mapped with the accuracy required for
the stimulus in question.

The device of the picture is probably from 1930s. It is one basic
device for ophthalmologist's practice and is much more sophisticated
nowadays.

Greetings! Veijo"

Veijo told that he has made an own objective to Mamiya camera using this perimeter to measure the angles a person uses.!