Influence of the autonomic nervous system balance on pupillary response during far‐to‐near accommodation in healthy children

Purpose To study the pupillary response during far‐to‐near accommodation in healthy children depending on their type of autonomic nervous system balance and the age. Methods A total of 269 healthy children (538 eyes) aged 6–18 y.o. were examined. They were divided into three groups according to the types of autonomic nervous system balance (sympathotony, parasympathotony, normotony) using Kerdo's index: V.I. = 100 × (1–DAP/Pulse), where DAP – diastolic blood pressure (mmHg), Pulse – heart rate (beats per min). The pupil area during the far‐to‐near accommodation was measured by video‐oculography. The maximal pupil area (Smax, mm2) was measured when the eyes fixed the object at distance 100 cm, the minimal pupil area (Smin, mm2) – when the eyes fixed the object at distance 10 cm. The amplitude of pupil area change (A = Smax–Smin, mm2) was calculated. Then the amplitude of pupil area change for 1 dioptre of accommodation during far‐to‐near response was calculated as A/9 (mm2/dioptre). Results The value Smax was the biggest in children with sympathotony (95% confidence 51.0–60.8 mm2), smaller in children with normotony – (20.0–44.0 mm2) and the smallest in children with parasympathotony – (19.1–32.4 mm2). In children with sympathotony, the average values of A/9 were: 4.04 ± 1.08 in children 6–9 y.o., 2.93 ± 0.17 – in children 10–14 y.o. and 3.74 ± 0.13 mm2/dioptre in teenager 15–18 y.o. The values of A/9 in children with parasympathotony were much smaller, that is 1.31 ± 0.76, 1.53 ± 0.67 and 2.24 ± 1.33 mm2/diopter, respectively. In children with normotony, the values of A/9 were the middle ones: 1.42 ± 0.65, 2.48 ± 0.89 and 3.43 ± 1.09 mm2/dioptre, respectively. Conclusions The difference in the amplitude of pupil area change during the far‐to‐near accommodation in healthy children aged 6 to 18 years is influenced by the type of autonomic nervous system balance. The biggest values were in children with sympathotony and the smallest in children with parasympathotony.