An electro-ophthalmographic study of the behavior of the fixation of amblyopic eyes in light- and dark-adapted state: a preliminary report.

The ability for steady fixation is not as good in eyes with reduced visual acuity as it is in eyes with normal vision. One should, therefore, expect eyes with strabismic am-blyopia not to fixate as steadily as do eyes with standard vision, or the sound eye of the same person. The fixation pattern of amblyopic eyes has received of late years a great deal of attention, particularly in the European liter­ ature. The mode of fixation has been cor­ related with the visual acuity and a new form of treatment, based on an evaluation of the mode of fixation, has been developed. 1 The fixation reflex acts as an adjustment which places and keeps the object of atten­ tion on the fovea as the retinal area of highest visual acuity. When this is achieved the object of attention is perceived with optical distinctness and "fixated." The movements of the eyes which occur in re­ sponse to the appearance of an object some­ where in the field of vision and which enable the eye to assume fixation of that object have been termed saccadic movements. Electro-ophthalmography provides a valu­ able method for the registration and analysis of both the fixation movements and the sac­ cadic movements of the eyes. This method is based on the fact that there exists an electrical potential between the cornea and the posterior pole of the globe. This resting potential is not affected by eye movements, but eye movements change the relationship of the electrical field of the eyes to fixed electrodes placed somewhere near the globe. Such electrodes will pick up positive or negative charges which, when properly am­ plified and recorded, will result in positive or negative deflections, according to the di­ rection of movement of the eyes. The graphic response so obtained is usually referred to in the literature as an electro-oculogram, but we prefer to call it electro-ophthalmogram (EOG) to avoid an unnecessary hybrid for­ mation. The electro-ophthalmographic behavior of the fixation movements and the saccadic movements of amblyopic eyes have been the subject of two recent studies by Macken-sen. 2 ' 3 This author has reported disturbances of the fixation ability of amblyopic eyes ranging from oscillating movements to jerky fixation movements, whereas the sound eye always remained steady within the limits of the recording method. To learn more about strabismic ambly-opia, and particularly about the quite ex­ traordinary ability of …