Over the past several decades, researchers have produced a body of literature that has given us an in-depth understanding of ciliary muscle anatomy. In vivo function remains an elusive aspect to study because of visualization difficulties. Recent advances in imaging technology have enabled us to continue to build on our current understanding of normal ciliary muscle function. These advances will elevate the level of comprehensive eye care we can provide for the entire visual system. Patients present with symptoms of accommodative dysfunction in optometric practices daily. While reading additions successfully alleviate these symptoms in the young and old alike, continued research is needed to gain a greater understanding of the in vivo muscle function in young patients with accommodative dysfunction and also after presbyopia onset. A recent review article has shown that multiple companies are working to develop accommodative intraocular lenses (IOLs) that rely on the action of the ciliary muscle; although, there remains a limited understanding of presbyopic muscle function.1 In addition to presbyopia, other types of accommodative dysfunction are also important to consider because our daily activities increasingly place demands on our ability to see clearly at close distances, i.e., computer use, video games, electronic book readers, smart phones, etc. Few studies have explored the prevalence of accommodative dysfunction in the general population, but 60% to 80% of patients diagnosed with binocular vision disorders have been found to suffer from accommodative dysfunction.2–3 The symptoms that are commonly associated with accommodative anomalies include blurred vision, headache, ocular discomfort, ocular or systemic fatigue, and loss of concentration during a task performance. Studies have shown vision therapy can improve both accommodative amplitude and facility, as well as increase the magnitude and velocity of accommodative responses.4–5 Nonetheless, specific muscular and/or neurological changes that might take place during vision therapy remain unmeasured and the exact effects of therapy remain unknown. Similarly, an increased accommodative lag has been observed after the onset of myopia, but we have been unable to identify the source of this anomaly in the accommodative system.6 Further studies are needed to provide a complete understanding of the childhood development and then the gradual decline of the human accommodative system and how it may relate to myopia, accommodative dysfunction, and the feasibility of IOLs that restore accommodation. Until recently, however, we have not had the imaging capability to measure in vivo changes in the ciliary muscle with accommodation. Recent studies have successfully used magnetic resonance imaging (MRI), ultrasound biomicroscopy (UBM), and anterior segment optical coherence tomography (AS-OCT) to visualize the ciliary muscle and/or to make measurements of the muscular changes that take place with accommodation.7–10 The present study combined the imaging capabilities of the Visante™ AS-OCT (Carl Zeiss Meditec™, Dublin, CA), which is capable of imaging the ciliary muscle and allows for further extraction of thickness measurements,11 with simultaneous monitoring of accommodative status (vertical meridian) by the PowerRefractor II (MultiChannelSystems, Reutlingen, Germany). Combining data from these two devices with knowledge of ciliary muscle anatomy allows one to make measurements of changes in ciliary muscle thickness while accounting for the subject’s accommodative response. In addition, the Visante™ is a non-contact, non-invasive, imaging system that is also easy to operate. It acquires images in a rapid fashion that makes it possible to image the ciliary muscle in adults and children.12–13
