All Plusoptix measuring devices will first take pictures of the eyes. The desired measurement values are then automatically determined on basis of these pictures. Good pictures of the eyes are therefore the key to a precise measurement.
A good image of the eyes is characterized by several factors:
1. Focus on camera
In order to avoid incorrect measurements in the periphery of an eye, the eye must be aligned with the camera. The alignment of the eye is recognized on basis of the position of the corneal reflex (1st Purkinje reflex) in the camera image.
All Plusoptix measuring devices automatically check whether this corneal reflex is central (within the inner circle of the gaze map). If the eye is not aligned with the camera, the camera image is discarded and further images are recorded until the patient focuses on the camera.
2. Illumination of the eyes
Correct measurement values cannot be determined in an overexposed or underexposed image of the eyes. Since each eye reflects the incident light to different degrees, depending on the pigmentation of the retina, the lighting must be individually adapted to the patient.
All measuring devices from Plusoptix check the brightness of the pupils. If they are too light or dark, the LEDs are automatically adjusted, so that the eyes are optimally illuminated depending on the pigmentation.
3. Maintaining the correct measuring distance
The algorithms for determining the measured values are based on a specified measuring distance. If the correct measuring distance is not observed, the tolerance of the measured values increases.
For this reason, all Plusoptix measuring devices support the user in maintaining the correct measuring distance. Only images with the correct measuring distance are automatically used to determine measured values.
For the precision of our measuring devices, it is crucial that measurement values are only determined on basis of good pictures of the eyes (alignment, illumination and distance). Therefore, incorrect measurements due to incorrect operation are excluded.
In addition, our measurement algorithms use statistical methods to detect incorrect measurements during the measurement. If an incorrect measurement is detected, all previous measurement images are discarded, and the measurement is continued until acceptable results are available. Therefore, it is not necessary to repeat a measurement.
Please contact us if you have any further questions about the precision of our measuring devices.