■ Full Question
We perform all cases with mydriasis, but even with mydriasis, there are occasions when the upper and lower laser beams cannot fit within the pupil diameter. It feels difficult at moderate mydriasis. Even when irradiating from the very edge of the pupil margin, there were several patients where either the upper or lower beam could not fully enter.
What pupil diameter (in mm) is needed to ensure reliable imaging?
■ Answer
The NAVI (dual-beam type) is designed so that the laser passes through the inside of a circle with a diameter of just under 5 mm.
Measurement is possible if the pupil is dilated wider than the circle drawn on the iris viewer screen at the lower right of the display.
However, this instrument is very sensitive to the anteroposterior alignment. Misalignment of the anteroposterior position between the eyeball and the camera can make it difficult for the laser to enter.
Please note that if the subject moves after the initial focus adjustment in the iris viewer, it becomes difficult for the laser to enter.
Iris Viewer