A pupillometer allows the measurement of the pupil size. This pupillometer accurately measures scotopic (in low illumination state) pupil size and corneal diameter of cataract and refractive candidates prior to surgery. The technology utilizes light amplification  to allow visualization of the patient’s pupils in a darkened room. The built-in reticle in the instrument provides measurement of vertical and horizontal corneal diameter that is important for the ophthalmologist.