[Influence of the functional status of the autonomic nervous system on the development and course of habitual...

Habitual excessive accommodation (HEA) in children is often accompanied by signs of autonomic imbalance, which substantiates the need for a comprehensive study of autonomic regulation in this condition.

This study aimed to investigate the features of autonomic regulation in children with habitual excessive accommodation (HEA).

A total of 104 children aged 6-17 years were examined: the main group comprised 54 patients with HEA and the control group included 50 children without this disorder. Mean manifest spherical equivalent was -1.75±0.60 D in the main group and -0.85±0.50 D in the control group (p<0.001); cycloplegic spherical equivalent was -0.72±0.52 D and -0.45±0.46 D, respectively (p<0.01). Ophthalmological examination included assessment of accommodative functions, pupil diameter, and cardiointervalography (CIG).

Children with HEA had lower accommodative amplitude (8.6±1.9 vs. 11.2±2.1 D), reserve (1.4±0.6 vs. 2.6±0.7 D), and facility (5.3±1.8 vs. 9.1±2.0 cycles/min; p<0.01), as well as lower (p<0.001) parasympathetic heart rate variability (HRV) indices - standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), percentage of NN intervals >50 ms (pNN50), and high-frequency power (HF), while sympathetic markers - low-frequency power (LF), sympathovagal index (LF/HF), and stress index (SI) - were higher (p<0.001). Pupil diameter was smaller (3.96±0.75 vs. 5.04±0.49 mm; p<0.001). The amplitude of accommodative miosis (Δ_accom) correlated positively with LF/HF (r=0.34) and negatively with SDNN and HF (r≈-0.34; p<0.05). Autonomic imbalance was most pronounced at ages 14-17 and in grade 3 HEA (LF/HF=2.67±0.3; SI=200±35).

HEA is associated with reduced parasympathetic and increased sympathetic activity. Cardiointervalography and pupillometry are informative for early detection of autonomic maladaptation.