Dynamic Range of Focus of the Eye: Understanding Biomechanics and Kinematics: Part II

IN PART I OF THIS 3-PART series, we outlined the definition of ocular biomechanics and kinematics and described the mechanical laws under which they operate.¹ In this article, we describe the specific elements and motions responsible for achieving Dynamic Range of Focus (DRoF), including the phases of vision from accommodation to disaccommodation (near to far) and disaccommodation to accommodation (far to near). The ciliary muscles (CMs) and Bruch’s membrane-choroid complex (BMCC) represent the dynamic engine of DRoF. Interpreting the types of bidirectional forces produced by the critical moving structures during DRoF is essential to understanding the mechanics of the “Kinematic Chain” of events that occur to facilitate the fine-tuned dynamic focusing power our eyes can perform. The aim of this article is to provide a deeper dive into the anatomy and physics of the mechanisms that equip our eyes with DRoF capability and to further explore the elements of this sophisticated mechanism responsible for the adjusting power of the lens.