. Refraction and muscular imbalance, as simplified through the use of the ski-optometer. al tendency thereafter will be tostrive for the same relationship of vision withboth eyes. The refractionist should then aimto reduce the excessive amount of prism re-quired to give binocular vision, which can beaccomplished by muscular exercise. It must always be remembered before therefractionist is ready to employ the muscularexercise or second method, that the degree ofprism required to give the patient single bi-nocular vision must be determined with theoptical correction in place. The exercise mustbe
. Refraction and muscular imbalance, as simplified through the use of the ski-optometer. al tendency thereafter will be tostrive for the same relationship of vision withboth eyes. The refractionist should then aimto reduce the excessive amount of prism re-quired to give binocular vision, which can beaccomplished by muscular exercise. It must always be remembered before therefractionist is ready to employ the muscularexercise or second method, that the degree ofprism required to give the patient single bi-nocular vision must be determined with theoptical correction in place. The exercise mustbe practised daily in routine, a daily recordbeing essential. An Assumed Case We will assume a case where 42 degrees isrequired to enable the patient to first see thered streak as produced by the Maddox rod tothe extreme left. Through a continued grad-ual reduction of 4 degrees (or to 38 degrees),we next learn that the streak was carried overuntil it bisected the white spot of light, giving [78] Refraction and Muscular Inibaland single binocular vision and producing a position of Fig. 28—Simplified chart showing the prism action em-ployed in developing a weak ocular muscle through alter-nating prism exercise. Either side of 38° in excess of 4causing diplopia. The patient has now established the limita-tion of the exercise, which is four degrees,this limitation being determined by the dif-ference between the point where the streakwas first seen to the extreme side and where itbisected the spot. The same amount of fourdegrees should then be used for the opposite [79] Refraction and Muscular Imbalance side, thus reducing the prism strength to 34degrees. This again produces diplopia, because ofthe lesser amount of prism power employedto give single binocular vision. The refrac-tionist should then return to 38 degrees, wheresingle binocular vision had originally beendetermined (Fig. 28), alternating back to 42,returning to 38, over to 34, back to 38, and soon. This procedure
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