# Changes of Gait Patterns after Correction of Refractive Error in the Elderly with Cataracts
## 1 Introduction  
Gait is a fundamental and natural aspect of human movement involving periodic physical movement [1]. The synchronization of various types of sensory information is essential for the maintenance of stable movements while walking. First, the vestibular system has a function in recognizing the senses involved in rotational movements and linear acceleration during walking. Second, the position and velocity of all body parts, contact with external objects, and direction of gravity are determined by the somatic system, which functions as a sensor. Finally, information about the surroundings, locations of obstacles, and ground conditions is collected by the visual system [2]. In general, the evaluation of gait patterns is based on the temporal and spatial characteristics of the gait cycle. Step length, stride length, walking velocity, and cadence are factors that can have an effect on gait patterns. Gait patterns can vary depending on the ground conditions [3], with the occurrence of significant changes in walking velocity and step length according to physiological factors such as aging [4] and gender [5]. Step width is related to balance control, and an increase in step width will lead to greater stability, making this a possible compensation for instability [6]. In addition, pathological causes such as stroke, arthritis, diabetes, and Parkinson's disease can destabilize gait patterns [7; 8]. The modification of gait patterns by using visual information occurs through feedback mechanisms from various pathways. Walking velocity is usually influenced by the flow of visual stimuli. As reported by [PERSON] and [PERSON], their study's participants showed increased stride length after the rotation speed of an optokinetic drum was doubled [9]. [PERSON] et al. [10], who performed an analysis of changes in gait patterns according to lighting conditions, reported that walking velocity was decreased and step length showed a significant decrease under dark lighting conditions. In a study on vision problems that can affect gait patterns, [PERSON] et al. [11] reported on simulated cataracts, including data on decreased visual acuity and contrast sensitivity, and a narrow visual field; they found that even young adults can be affected through increases in the frequency of collisions with obstacles and deviations from intended walking paths. According to [PERSON] [12], as a result of visual impairments, individuals with congenital low vision are not able to learn appropriate concepts regarding movement during the process of development. Visual impairment can be a cause of walking errors such as collisions, errors made at intersection crossings and road crossings, and significantly reduced walking stability and delayed walking time. Therefore, the maintenance of a stable gait requires the prediction of future movements along with awareness of the current surroundings and the ability to adapt to changing surroundings. The acquisition of appropriate and continuous visual information is essential [13]. Refractive errors are the most common causes of visual blur, which occurs when parallel rays that have entered through the eyes fail to focus on an image on the retina while the ciliary muscle is in a relaxed state [14]. Although refractive errors are common, they may not be considered a serious problem because they do not cause fatal problems compared to other eye diseases. Visual blur caused by refractive errors can interfere with the acquisition of appropriate visual information for the maintenance of a stable gait; however, until recently, research on refractive errors and gait patterns has been limited due to the aforementioned prejudice. The authors of the present paper previously investigated the effects of refractive errors by type on static postural control and fall risk [15; 16; 17].