Horizontal Heterophoria Modifications by Means of Thin Proprioceptive Stimulations Applied on the Foot Sole: A Randomised Study

Some authors have demonstrated that proprioceptive stimuli applied on the feet soles can interfere on the ocular muscles. However, these studies do not clarify possible functional differences between the dominant eye and the non-dominant eye. The purpose of this randomised study is to establish if the positioning of an Internal Heel Wedge (IHW) and an External Heel Wedge (EHW) can modify horizontal heterophoria, determine dissimilar behaviours between the dominant eye and the non-dominant eye. Forty-two healthy subjects, with a right dominant eye, were tested. The 1.5 mm-thick proprioceptive stimuli were shaped out of a cork half-moon. The experimental group was divided into two groups: IHW group and EHW group. Both groups performed the "Baseline" (without mechanical stimulation) and "After 15'" (following a fitting period of 15 minutes on a treadmill with mechanical stimulation) trials. The control group performed the same trials without any podalic stimulation. Meaningful changes were observed on the horizontal heterophoria of the non-dominating eye with an IHW. Non-statistically significant variations were observed with an EHW and in the Control group. A thin heel wedge applied on the foot sole was able to generate functional changes in the non-dominant eye and could help health professionals develop increasingly personalised rehabilitation programmes.