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W.E. Adams, J. Tuck, S. Richardson, H. Haggerty, S. Hrisos, M. Clarke; Distance Stereopsis Testing in Children Using the Frisby-Davis Distance Stereopsis Test (FD2) . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4820.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To establish a normal range of values using a new test of distance stereopsis measurement in 3-5 year old children with normal vision. Method: Tests were performed using a new test of distance stereoacuity called the Frisby- Davis Distance Stereotest (FD2). This test uses four back-illuminated and differently shaped plastic objects. These are set in a transparent frame pointing towards the observer mounted on rods. On each trial, one shape is set to be nearer to the observer than the others. The shapes are sufficiently dark to obscure the rods so appear to be free floating. The observer is to choose which one is nearer than the others and the shapes are altered from presentation to presentation. The disparities can be selected in the range from 50 to 4" (sec arc) at 6 metres or 200 to 15" at 3 metres. Each child had their vision checked and those with vision < 6/9 Snellen in either eye or strabismus were excluded. The child was then asked to determine which shape was displaced and the shapes were altered on each presentation until a reliably repeatable level of stereopsis was reached. 57 children were examined with a mean age of 4.1 years (Range 3 - 5.8 years) Results: The mean stereopsis value was 35.5" (Range 3 - 154 sec of arc) There is a significant correlation with age showing better stereopsis values with increasing age. (p= 0.014)This is dichotomised by age > or < 4 years. The number of children <4 =29 (range 3-3.9 years). The mean stereopsis in this group was 44.3" (range 12-154). The number of children > 4 years = 26 (range 4 - 5.8 years). The mean stereopsis in this group was 25.8" (Range 3 - 92). Conclusions: There are currently no good clinical measurements for distance stereoacuity in young children. The FD2 enables measurements of distance stereopsis to be carried out on young children. There is a significant influence of age on the stereopsis values, with older children attaining better stereopsis values. It is uncertain whether this is due to maturational, perceptual or behavioural factors.
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