THE STUDY OF OPTOKINETIC LOOK NYSTAGMUS IN CHILDREN - OUR EXPERIENCE

Seventy healthy children underwent an OKN trial. The authors have chos en to perform only four tests (slow and fast clockwise and countercloc kwise OKN) taking into account (in agreement with several internationa l studies) four parameters: sTAP, fTAP, sTSAP, fTSAP (where s and f in dicate the velocity of the shifting target slow or fast, TAP is total asymmetry percentage of the SSC-speed of slow components-and TSAP is t otal asymmetry percentage of saccades). They carried out the statistic al analysis of the results, which did not show peculiar difference bet ween child and adult OKN. The result of the test was independent of th e side first tested and of sex. The authors have tried to identify the normal range of values more suitable to the study of child OKN; on th e basis of the calculation of the 95% percentile the normality range w as wider than the range assumed for adults. The authors have alsb trie d to subdivide the results for three different groups of age (I = 3-7 years; II = 8-11 years; III = 12-14 years) in order to observe the deg ree of OKN maturation with age. From the results obtained the maturati on of OKN pathways seems to occur in the 7th year of age for the slow movements; the findings related to the fast movements are more doubtfu l and need further analysis. Finally, although the number of saccades interposed to the tracings depends on enormous variations unrelated to age, sex and first side tested, our data show their higher incidence during the slow test. (C) 1997 Elsevier Science Ireland Ltd.