Does Latent Strabismus Affect Stereoacuity?

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 study population 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 had exophoria, three had esophoria, and the remaining five had orthophoria. The mean angle of deviation in group B was 6.50±6.92 PD. This value was statistically higher than the mean deviation angle in group A (p=0.012). Though none of the esophoric participants achieved excellent stereoacuity, the distribution of the deviation types did not cause any difference between the groups (p=0.077). The mean age of group 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.