The Symptom Factor Values Obtained From A Normal Population.

To establish a range of "S factor" (Symptom factor) values from a normal population. The S factor is the ratio of near convergence (BO)/near point of convergence (NPC). The S factor has been shown to have a relationship with symptomatic versus asymptomatic patients in studies by Shippman et al, subjects with a low S factor were found to have a high correlation of experiencing near point symptoms. The subjects were one hundred twenty three fifth grade students from the Big Rapids school system. The following criteria were used, 20/40 or better visual acuity at distance and near, and 60 seconds of stereopsis or better at near. Data was generated from one hundred and eight patients that met the criteria.