Hirschberg-Test

The Hirschberg test, named after the German ophthalmologist Julius Hirschberg, is a simple and exploratory research method of strabismus, which makes the position of the Hornhautreflexbildchen advantage. It is mainly used in patients whose employees for other processes is not sufficient ( infants, small children) or that have a high degree of amblyopia regardless of the fixation.

The investigation is carried out with the help of a small light source ( ophthalmoscope, flashlight etc.).. In this case, the patient, the examiner shines in height of the nasal bridge from the front as closely as possible between both eyes. If there is no strabismus, the position of the light reflexes it is the same in both eyes. In this case, they need not necessarily centrally, but can also be shifted nasally or temporally. Decisive is the equality of the decentering, which depends on the so-called kappa angle to the angle between the line of sight and pupillary axis. However, there is a manifest strabismus, then the corneal reflections of both eyes are not exactly at the same places, but the reflex of the affected eye is shifted depending on squint deviation. This also means that rotational angle of deviation ( Zyklodeviationen ) can not be detected with the Hirschberg test.

In principle, the Hirschberg test is a qualifying process. One can estimate with some experience the squint angle also. This off-centering of the reflection corresponds to one millimeter from the pupil center to a deviation of about 8 °. In order to measure the size of a squint deviation, it is also possible to move the corneal reflection image of the squinting eye using a prism bar so far that its position is congruent to that of the other eye. The value of the prism corresponds then usually the objective angle of deviation. In general, however, this method of the squint angle measurement is more accurate with an error range of about 3 °. In addition, a possibly present kappa angle must be taken into account.

If the Hirschberg test used to quantify the measurement of squint angles, he is also known under the name Krimsky test.