Objective: To study the development of stereopsis in children from 30 to 50 months of age.
Methods: It was a prospective study.We examined the visual acuity and stereopsis of 152 normal children from 30 to 50 months of age. The stereopsis was examined with Titmus, RPS and TNO.
Results: In 152 children, a complete examination was performed in 119 children had visual acuity of >or= 0.6; 12 children had visual acuity of < 0.6; 21 children could not complete the examination. The mean age of these 21 children was significantly lower than the others. Using Titmus 60'', Titmus 100'' and RPS 60'' as the normal criteria, the normal ratio of near stereopsis acuity in the 119 children was correlated to the age by chi(2) test. They were divided into four groups by 5 month-age groups. The normal ratio in the 46 to 50 month group was significantly greater than that in the other three groups. The normal ratios was 89.9%, 94.1% and 95.0% for the criteria of Titmus 100'', RPS 200'' and TNO 240'', respectively.
Conclusions: The stereopsis in children from 30 to 50 months of age is still in developing status. We suggest using 100'' for Titmus, 200'' for RPS and 240'' for TNO as normal stereopsis criteria in 3 to 4 year old children. RPS provides a reliable procedure for the measurement of stereopsis acuity in preschool children.