Analysis of the dynamics of the human ciliary muscle during accommodation

Background. The magnitude of anterioaxial shift of the human ciliary muscle during accommodation and its ceasing of ciliary function with advanced age are still unknown. Patients and methods. A total 105 patients (aged 10-91 years) were examined by high-resolution ultrasound biomicroscopy during disaccommodation and voluntary accommodation. Accommodative changes in the total area of the ciliary muscle and in the outer contour were quantified with a specially developed software program for automatic contour determination. Results. A significant anterior shift independent of age was observed in the total area of the ciliary muscle and defined points on the outer contour of the muscle in the range of 56-121 pm, while the inward displacement was less obvious. A decrease in the magnitude of configurational changes during accommodation was observed with age. Conclusion. The new software program could be useful in further investigations of the accommodative process and evaluation of the potential causes of presbyopia.