A clinical technique for correcting diplopia with prism

We describe a technique to directly measure the angle and magnitude of any deviation, regardless of its direction. Knowing the angle and magnitude of an oblique deviation allows the clinician to find a prism correction faster and with more accuracy than by using the traditional method of combining vertical and horizontal prisms. We have applied this technique to 37 patients and have found a very high success rate using press-on or ground-in prism for both postsurgical and nonsurgical patients. All of the necessary materials are standard equipment for a routine eye examination. Even though a very similar technique has been described previously in the literature by another author, it does not appear to be known by many clinical optometrists. We hope the description of our technique will focus interest on this useful method for correcting very difficult diplopia cases.