Video vision development assessment in diagnosis and documentation of microtropia.

Background: Microtropia is under diagnosed in treated esotropia and in primary microtropia cases, where patients are young and uncooperative.

Method: Video Vision Development Assessment (VVDA) testing, which we have developed and previously described, captures multiple video frames images (30 per second) of the Breuckner red reflection (from the ocular fundus, a test for strabismus and ocular media abnormalities) combined with eccentric photorefraction. This method allows the highly critical discrimination of minimally off axis fixation (abnormal) to be differentiated from true on axis fixation (normal foveation) by the brightness difference in the images. We have examined with this method, VVDA, 533 consecutive strabismus patients ages six months to six years.

Results: 47% of esotropes and 23.8% of exotropes had microtropia.

Conclusion: VVDA is helpful in documenting microtropia in young uncooperative patients where the diagnosis may otherwise be missed, even when suspected to be present, due to lack of subjective test cooperation. Multiple video frames of the same patient (VVDA) allow dynamic detection of true fixation (normal foveation) versus slightly off axis fixation (abnormal, consistent with microtropia). VVDA is therefore superior to single photorefraction imaging in the diagnosis of microtropia.