正常人瞳孔对光反射的生物力学性能与年龄的相关性

Objective: To conduct a preliminary investigation of a biomechanical model of the pupillary light reflex in normal human pupils; to understand the relationship between the parameters of the model and age. Methods: This was a descriptive study. A total of 143 patients with normal eyes were enrolled in a case-series study at the Optometric Clinic Center of the Eye Hospital, Wenzhou Medical University, from February 2015 to July 2018. The pupillary light reflex (PLR) data were obtained using the pupillometer program of Oculus Keratograph 4. The biometric model fitting was applied to the PLR data compiled by Matlab software, which was solved using a step-by-step approximation method to obtain the elasticity coefficient and viscous coefficient of the pupil dilator muscle and constrictor muscle. The amount of resting time and impulsive sympathetic and parasympathetic nerves and the delayed response of the nerve impulse were also calculated. Results: A total of 143 subjects, 65 males and 78 females, aged 45.3±22.6 years, with an average pupil diameter (PD) of 5.58±1.06 mm participated in the study. The following parameters were calculated: elastic constant of the constrictor (k_c) 0.29±0.29 mN/g·mm², radius of the constrictor at rest (L_0c) 0.89±0.05 mm, elastic constant of the dilator (k_d) 1.27±1.08 mN/g·mm², dilator muscle resting length (L_0d) 3.40±0.28 mm, viscous constant of the pupil muscle (D) 3.57±0.15 mN·s/g·mm, muscle forces originating from the parasympathetic system induced by a light stimulus (f_p) 134.77±33.23 mN/g and from the sympathetic system induced by a light stimulus (f_s) 1.26±1.84 mN/g, muscle forces originating from the parasympathetic system at rest (f_p0) 0.19±0.26 mN/g and from the sympathetic system at rest (f_s0) 0.09±0.12 mN/g, the delayed response of the parasympathetic nerve impulse (t_p) 1.15±0.10 s and the sympathetic nerve impulse (t_s) 2.14±0.36 s. The K_c parameters of the PLR data increased with age and the parameters of the pupil-to-light reflection that decreased with age were PD, k_d, L_0d, f_p, t_p. The multilinear regression equation of predicting pupil diameter (PD) using the PLR model is PD=2.9585-0.0099×age+0.0059×f_p+1.3259×f_s0-1.4853×k_c+0.3006×k_d+1.0159×L_0d (F=79.906, P<0.001). Conclusions: By establishing the biomechanical model of PLR, the study obtained the elastic and viscous constants, coefficients, and parasympathetic and sympathetic nerves in PLR, which is beneficial to the application of PLR in autonomic neuro-related diseases.