Each Vision Monitor stimulator is equipped with a near infra red illumination and an high resolution camera (950 nm) which allow measurements of binocular pupils even under complete darkness.

These stimulators provide a precise control of the stimulation conditions parameters:

• illumination
• ganzfeld flashes with programmed intensity and frequency

The image of the eyes is collected and processed by computer to perform accurate measurements of the pupil sizes (accuracy = 0.1 mm). The pupil contour is outlined on the image to allow the control of measurement accuracy.

This exam performs measurements of pupil size under several levels of controlled illumination:

• high photopic (100 cd/m2),
• low photopic (10 cd/m2),
• high mesopic (1 cd/m2),
• low mesopic (0.1 cd/m2).

The acquired images can be printed and saved.

Application in refractive surgery:

• AAO American Academy of Ophthalmology (AMBROSIO & al, 2002): "In refractive surgery, the most relevant information is the pupil size at the mesopic and scotopic levels of illumination because of potential problems with glare, halos, and other visual phenomena in some patients under scotopic lower lighting conditions."
• ASCRS (STEINERT & al, 2003): "Measurement of pupil size in dim and room light. Pupil size is an important factor in counselling a candidate about night vision and planning the appropriate laser vision correction strategy."

Application in neuro-ophthalmology:

Pupil size measurements are also important in neuro-ophthalmology for the determination of lesions of the afferent (retina, optic nerve) and efferent pathways (ALEXANDRIDIS, 1985, LOEWENFELD, 1993).

Adie's tonic Pupil Under photopic illumination: only the left pupil constricts (top) After installation of pilocarpine: the right pupil constricts too (bottom).
(source: Dr Zanlonghi, Nantes)

The images of both eyes are acquired and processed in real time (30 images per second).
The program also performs an analysis of the temporal response and of the averaged response of successive visual stimuli (light flashes).

Analysis of the temporal response

Automated quantification of the following parameters:

• maximum diameter
• minimum diameter
• amplitude of constriction

Analysis of the averaged response

Automated quantification of parameters:

• Resting diameter, amplitude of constriction
• Velocities of constriction and dilation
• Latency of constriction
• ...

Vision Monitor systems compatible with this program:

• MonCV3: multifunction perimeter
• MonPack3: standard visual electrophysiology
• MonColor: advanced visual electrophysiology

Summary of specifications

• Invisible near infra red illumination (950 nm)
• Accuracy of measurements of pupil diameter = 0.1 mm
• Sampling frequency = 30 Hz under binocular conditions