Does Latent Strabismus Affect Stereoacuity?

Abstract

Objective: The purpose of this study is to determine the effect of latent strabismus on stereoacuity.Methods: Stereoacuities of normal individuals, ranging in age from 18 to 35 years, were measured using the TNO or Titmus tests. The studypopulation was divided into 2 groups regarding the achievement of the accepted excellent stereoacuity threshold of 30 arcseconds (group A)or not (group B). The relationship between latent deviation angles and stereoacuity levels were evaluated.Results: Latent deviation angles ranged from 0 to 35 prism diopters (PD). Both TNO (r=0.380 p=0.002) and Titmus (r=0.306 p=0.015)stereothresholds tended to increase as the latent deviation angles increased. Group A included 27 participants who had either exophoria(18) or orthophoria (9), and the mean deviation angle of this group was 3.07±3.26 PD. Group B included 36 participants, 28 of whom hadexophoria, three had esophoria, and the remaining five had orthophoria. The mean angle of deviation in group B was 6.50±6.92 PD. Thisvalue was statistically higher than the mean deviation angle in group A (p=0.012). Though none of the esophoric participants achievedexcellent stereoacuity, the distribution of the deviation types did not cause any difference between the groups (p=0.077). The mean age ofgroup A was found to be higher than that of group B (p=0.006).Conclusion: Latent deviation can mask true stereosensitivity potentials of subjects to some extent during the stereotesting procedure.