Working principle of a transillumination test
All Plusoptix devices use the measuring principle of an transillumination test. In a transillumination test, a beam of light is projected into the eye and reflected by the retina. The light beam illuminates the central part of the cornea, the lens, the vitreous humor and the retina. This measuring principle is used in many eye examinations. Depending on the task, a direct ophthalmoscope (red reflex test), an indirect ophthalmoscope (fundus exam) or a retinoscope (retinoscopy) are used.
Unlike other transillumination tests, Plusoptix devices avoid glare of the patient, by using infrared light. The pupils remain large even without dilation. The device records camera images of the illuminated pupils, which can be stored or printed for further analysis and documentation. The camera images are therefore particularly suitable for checking whether abnormal retinal reflexes or media opacities are present (Red Reflex or Bruckner test).
Since Plusoptix devices additionally measure the refraction and the measuring principle of the transillumination test is also used for the retinoscopy, measurements with Plusoptix devices were initially often referred to as video or photo retinoscopy.
Test area with ...
Without cycloplegia (non-invasive)
➡ Test area is quadrupled if pupil size is doubled. ➡
Transillumination test with ...
Plusoptix analyzes image and provides readings for sphere, cylinder, axis, pupil sizes, gaze asymmetry and pupil distance, automatically.
In order to detect an abnormal reflex or a media opacity, an eye care professional needs to review the image provided by Plusoptix, and document his observation, manually.