Centrally fixed flicker thresholds in amblyopia.

Theories as to the etiology of amblyopia (also called amblyopia ex anopsia, strabis­ mus amblyopia, and amblyopia without ophthalmoscopic signs) may roughly be divided into two groups depending upon whether the primary defect is postulated in the cere­ bral cortex or in the retina. Wald and Burian who are among the most lucid ad­ vocates of the former position described measurements on five cases in whom the ab­ solute threshold foveally and peripherally in both rods and cones, light adapted, and dark adapted were perfectly normal. They regard the dissociation of form vision and light per­ ception as characteristic of the vision of amblyopic eyes. Studies of the critical flicker frequency in amblyopia have also been made. Unfortu­ nately, the available data in this regard are equivocal. Miles repeated some of the ex­ periments of Teräskeli who found in the amblyopic eye a reduction of "the normal trend" for the critical flicker frequency in the center to be somewhat lower than in an area 10 degrees into the peripheral field. Miles obtained a similar result. On the other hand Feinberg found that in the normal eye the critical flicker fre­ quency was highest at the center of the field but decreased the farther out into the pe­ ripheral field one moved. In amblyopia the critical flicker frequency in the peripheralfield was frequently as high as that in the center because the central critical flicker fre­ quency was reduced in the amblyopic eye.