Pupillometric Quantification of Residual Rod and Cone Activity in Leber Congenital Amaurosis

Figure 1. Mean (SD) pupil response (calculated as pupil size at peak contraction divided by prestimulus baseline size) vs stimulus intensity (blue and red light) for 10 control subjects. Open circles indicate null response. Regression analysis through responses to dimmer light intensities (−4.0 to −1.0 log cd/m²) describes rod activity and determines response thresholds (arrows). The leftward shift of blue light responses indicates greater sensitivity of rods to blue light.

Figure 2. Pupil responses (calculated as pupil size at peak contraction divided by prestimulus baseline size) to red and blue light stimuli for 4 patients with Leber congenital amaurosis, including patient 1 (aged 30 years, female, RDH mutation, light perception, no visual field) (A), patient 2 (aged 44 years, female, TULP mutation, light perception, 3° central field) (B), patient 3 (aged 15 years, male, RPE65 mutation, visual acuity 20/400, 5°-10° central field) (C), and patient 4 (aged 29 years, female, RDH mutation, visual acuity 20/200, 1°-2° central field) (D). Compared with control subjects, patients with Leber congenital amaurosis have marked loss of rod and cone sensitivity (large rightward shift of pupil responses). Rod-mediated pupil responses are mostly absent (open circles). Responses to bright red stimuli are reduced but measurable, indicating residual cone activity.