This is an example of the Bruckner test which is one of the "light-reflex" tests used to diagnose strabismus. This test is typically used by primary care physicians (e.g. pediatricians) to grossly screen for strabismus. If strabismus is present, then the deviating eye will have a lighter and brighter red reflex compared to the fixating eye. The Bruckner test is also used to screen for media opacities (e.g. cataract, vitreous hemorrhage) as well as anisometropia.
The Hirschberg method involves shining a penlight directly at the patient and observing the position of the corneal light reflexes of both eyes. If both light reflexes are centered in the pupils of both eyes, then the patient is orthotropic.
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Krimsky method is a type of light reflex test where the examiner centers the light reflection on the deviating eye with an appropriately-powered prism. Thus, this method can help quantify the deviation.