Alternating Hyperphoria

THE original aim of this investigation was the classification of cases of hyper- tropia and hyperphoria.Much more frequently than we had expected, we found alternating hyperphoria, and almost all the cases of hypertropia which were not clearly of a paretic nature proved to be complicated by this pheno- menon.When a large number of cases of hypertropia and hyperphoria had been examined, it became evident that a definite syndrome was present in the majority, alternating hyperphoria being the dominating feature.The material was provided by the patients of the Amsterdam Motility Clinic.Alternating hyperphoria proved to be so frequent that more than one hundred cases were noted in 18 months. Methods of ExaminationMost of the patients were examined several times.Special attention was paid to hereditary factors, to the time when squinting was first observed, and to nystagmus.The horizontal angle of squint and the degree of hypertropia were measured by the method of reflex images and a tangent-screen.Quantitative data concerning the vertical angle of squint seldom came within the scope of this study.The following directions of gaze were examined:(1) Primary direction of gaze, also with head tilted to the right and to the left.(2) Looking to the right and to the left.(3) Looking upwards and downwards.When possible we always examined with both the right and the left eye fixing.Examinations in diagonal directions of gaze were frequently carried out but produced no useful data.Examination of the position of the eyes by means of subjective methods was often unsuccessful because of the absence of diplopia either through suppression or through abnormal retinal correspondance.Never- theless examination by means of the Maddox rod yielded important results to which we shall return later on in this paper.Cyclophoria was determined by two Maddox rods (the vertical lines observed had to be placed by the patient perpendicularly upon each other), or by the synoptophore..Occlusion of the Eye.-As a rule one of the eyes was occluded by the examiner's hand, while the non-occluded eye was directed to a spot-light.All the movements of both eyes were carefully examined (the occluded eye by studying it from the side behind the hand.)At first we examined the reactions to occlusion inthevarious directions of gaze, but they are not to be influenced to any appreciable degree, and *Rceived for