Distance associated heterophoria measured with polarized Cross test of MKH method and its relationship to refractive error and age

PURPOSE: Due to the expansion of modern optotype liquid crystal display with the help of positive polarization, measurement of heterophorias (HTFs) by means of polarization, and thus partial dissociation of perceptions, has become more and more accessible. Our aims were to establish the prevalence of distance associated HTF by measuring with polarized Cross test of MKH [measuring and correcting methodology after H-J Haase] method and its association with age and refractive error in clinical population of wide age range. METHODS: A cross-sectional study was carried out with 170 clinical subjects aged 15–78 years with an average age of 40.7±16.62 years. All the participants had best-corrected visual acuity better than 20/25, stereopsis ≤60 second of arc, no heterotropia, not undergone vision therapy, and had no eye disease. The distance associated HTF was measured with the Cross test of the MKH methodology. The quantification of associated HTF was acquired by means of Risley rotary prism. RESULTS: The occurrence of distance associated HTF was found in 71.2% of participants. Of the total, 36.5% of the cases had esophoria (EP), 9.4% EP and hyperphoria, 10.6% exophoria (XP), 7.1% XP and hyperphoria, 7.6% hyperphoria, and 28.8% orthophoria. The mean distance horizontal associated HTF was +0.76±2.38 Δ. With EP, the mean value was +2.47±2.18 Δ, and with XP, −2.1±1.72 Δ. There was no correlation observed between the amount of distance associated HTF and age. There was no effect of the type and amount of a refractive error on the amount of distance associated HTF. CONCLUSION: A high occurrence of distance associated HTF was revealed while performing the polarized Cross test of MKH method. The relationship between the degree of associated HTF and refractive error and age was not proved.