Prevalence of Heterophoria in Tibetan Grade-One Students: The Lhasa Childhood Eye Study

Table 1

Risk factors of amblyopia definition.

Risk factors
Strabismus	Strabismus on examination
	Previous strabismus surgery
Anisometropia consistent with the worse eye	≥1.00 D SE anisohyperopia
	≥3.00 D SE anisomyopia
	≥1.50 D SE anisoastigmatism
Past or present obstruction of visual axis which could not explain the vision loss directly