Pupillary abnormalities in type I diabetes occurring during adolescence. Comparisons with cardiovascular reflexes

To evaluate computerized infrared pupillometry for the assessment of autonomic neuropathy in adolescents with type I diabetes.

We measured resting pupil diameters and pupillary light reflexes in 142 adolescents with type I diabetes (72 boys and 70 girls, 10.4-19.8 yr of age, duration of diabetes 0.7-18.3 yr) and in 75 nondiabetic control subjects (29 boys, 46 girls, 11.3-19.8 yr of age). All study participants were assessed using four standard cardiovascular tests: maximum-minimum heart rate during deep breathing (mean of three cycles); heart-rate change during a Valsalva maneuver (Valsalva ratio, mean of three maneuvers); lying-to-standing heart-rate change (30:15 ratio); and lying-to-standing BP change.

Mean resting pupil diameters were significantly smaller in the diabetic group: 6.28 +/- 0.06 vs. 6.77 +/- 0.11 mm, P < 0.0001); and significantly smaller with greater duration of diabetes (r = -0.29, P = 0.0006) and higher levels of GHb (r = -0.24, P = 0.004). Patients with retinopathy grade 30 or more (Wisconsin 191 grading) had significantly smaller resting pupil diameters: 5.9 +/- 0.16 vs. 6.4 +/- 0.12 mm, P = 0.008). The phasic light reflex as determined by reflex amplitude and maximum constriction velocity was significantly reduced in the diabetic group: 2.27 +/- 0.03 vs. 2.44 +/- 0.04 mm, P = 0.0009; and 6.68 +/- 0.12 vs. 7.24 +/- 0.16 mm/s, P = 0.007). Reduced reflex amplitude was related to a longer postpubertal duration of diabetes (r = -0.18, P = 0.04). We found no association between pupillary and cardiovascular tests.

Infrared computerized pupillometry demonstrates subclinical diabetic autonomic neuropathy as early as adolescence. Its presence seems to be related to longer duration of diabetes and unfavorable metabolic control.