Low-tech technique adequate for pupil measurement

April 18 - Washington, DC - Use of a Rosenbaum card with a red or blue light source affords accurate and reproducible measurement of scotopic pupil size, said Thomas J. Harvey, MD.

Dr. Harvey reported the results from a study in which horizontal scotopic pupil diameter was measured by two observers bilaterally in the nonaccommodative state in 100 patients using four different methodologies: the Iowa infrared pupillometer, the Colvard pupillometer, and the Rosenbaum card with blue and red light.

ANOVA testing showed there was excellent agreement between observers for all methods. Statistical analysis with the student's t-test showed measurements obtained with the Rosenbaum card using red light were nearly identical to the values measured with the Iowa infrared pupillometer, which was used as the gold standard comparator. Pupil size measured smaller on average using the Rosenbaum card with blue light versus the Iowa device, whereas the Colvard pupillometer measurements were statistically significantly smaller compared with all other techniques.

"Pupil size has been a highly publicized component of the refractive surgery preoperative evaluation, but the clinical significance of a larger pupil size remains unclear. While lower technology methods for measuring pupil size have been criticized in the literature, the results of this study demonstrate they can offer an acceptable technique," Dr. Harvey said.

Dr. Harvey has no financial interest in any of the technology he discussed.