Abstract
Purpose: :
Preverbal children with amblyopia risk factors can be challenging to manage, as they may have a fixation preference but may or may not have amblyopia. We developed a user and patient friendly test using visually evoked potentials to aide in the management of such children.
Methods: :
We tested 33 normal children and 43 amblyopic individuals (age 3-12 years) using the Diopsys NOVA-TR system. A checker board pattern reversal visual evoked response was produced at 2 Hz for each of 5 spatial frequencies. Stimuli were presented for 10 seconds (20 reversals) and the entire test typically took less than five minutes. The relative (percentage) diminution of P100 amplitude between the eyes, and the absolute prolongation of the P100 latency for each spatial frequency were compared.
Results: :
A 9 millisecond difference in P100 latency for at least 2 spatial frequencies, or a twenty-five percent diminution in P100 amplitude between eyes for at least 3 spatial frequencies correctly identified 94% of normal subjects as being normal, and 81% of amblyopic subjects as being abnormal, including 72% of subjects with mild amblyopia (2 or 3 lines of intra-ocular difference), and 88% of subjects with moderate or severe amblyopia (4 or more lines difference).
Conclusions: :
A pattern reversal visual evoked response at 5 spatial frequencies can be used to correctly identify children with amblyopia, without misclassifying significant normal individuals. This is important since fixation preference testing can be unreliable in detecting amblyopia in preverbal children.
Keywords: amblyopia • visual development