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Discordant pursuit asymmetry and esotropia in monozygous twins
Pradeep Sharma1, Arthur L Rosenbaum, Terre Vives
1Department of Ophthalmology, University of California, Los Angeles, USA.
Purpose:
To report the relationship between infantile esotropia and asymmetry of monocular pursuit tracking.
Design:
Observational family case series.
Methods:
A twin pair discordant for infantile esotropia was confirmed by DNA analysis to be monozygous at 99.95% probability. Digitally sampled electro-oculographic recordings of monocular horizontal pursuit eye movements were performed for the twins and their orthophoric father.
Results:
Mean directional asymmetry for right and left eyes was 31% and 5% for the esotropic twin, 10% and 8% for the orthophoric twin, and 5% and 6% for the father. The asymmetry was statistically significant only for the deviating right eye of the esotropic twin (P = 0.0217).
Conclusion:
In this family, monocular pursuit asymmetry is probably not a heritable predisposition to infantile esotropia, but a consequence of early strabismus. Discordance of infantile esotropia and pursuit asymmetry in monozygous twins implicates environmental in addition to genetic causes.