This test is used to assess the symmetry of binocular fixation by comparing the brightness of the red reflex in each of the two eyes using a handheld direct ophthalmoscope.
This test is mainly used in infants, young children and patients with limited co-operation and can be used to screen for strabismus, anisometropia, media opacities, and posterior pole abnormalities.
The purpose of this test is to assess the symmetry of binocular fixation by comparing the brightness of the red reflex in each of the two eyes and is particularly useful for very young patients with limited co-operation.
Instruct the patient to remove any refractive correction.
Dim room lights.
Direct the ophthalmoscope toward the patient’s eyes from a distance of 80 to 100 cm using a large round patch of light to illuminate both pupils simultaneously.
Instruct the patient to look at the centre of the light.
Look through the peephole of the ophthalmoscope and dial in the lens that gives a clear view of the patient’s pupils.
While observing the Hirschberg reflexes against the red reflex in the pupil, the brightness of each red reflex can be compared.
If the two reflexes are equally bright, there is binocular fixation.
If the reflexes are not equally bright, the darker red reflex indicates the fixing eye, and the brighter, lighter, or whiter reflex indicates the non-fixing eye.
The difference in brightness may be caused by strabismus, anisometropia, anisocoria, media opacities, or posterior pole abnormalities
Note how this contrasts with the use of a retinoscope when the reflex of an affected eye is often the darker.