If being used on a non- dilated eye, make sure the system is set with the illumination and viewing systems at maximum convergence. This setting reduces the stereoscopic separation, and so should be set to the maximum separation that is able to produce a stereoscopic image. The practitioner should first illuminate the patient's pupil area by pointing the head and hence the illumination towards the patient's eye. Interpose the BIO lens close to the eye about 2 cm, and centre the lens on to the pupil. The lens should be held with the more convex side towards the practitioner.
Many lenses have a white or silver line indicating the side to be held closest to the patient.
Pull back the lens away from the patient's eye, at the same time taking care to keep the illumination centred on the pupil. Whilst withdrawing the lens, the practitioner will find a distance that provides an optimum field of view. Having obtained an image filling the BIO lens, the fundus may then be examined by moving around the patient if reclining, or by redirecting the patient's fixation if seated. It is at this point that it becomes obvious that it is definitely preferable to have the patient reclining if possible. Fine tuning the fundus view Tilt the BIO lens to remove undesirable reflections.