Optometry: Open Access
Open Access

Visual Stability, Whole-Body Vibration, Vision.

Whole-body vibrations (WBV) have significant implications for human comfort and well-being, particularly in industries where individuals are exposed to prolonged periods of vibration, such as transportation, construction, and manufacturing. While several factors contribute to the perception of vibration comfort, one often overlooked aspect is the influence of vision [1]. The human visual system plays a vital role in interpreting sensory information related to motion and spatial orientation. It provides crucial visual cues that help the brain integrate sensory inputs and establish a stable frame of reference during vibrations. This article delves into the influence of vision on whole-body human vibration comfort levels, highlighting the importance of visual cues in mitigating discomfort and enhancing overall well-being. By understanding this relationship, we can design environments, vehicles, and equipment that optimize comfort and reduce the potential negative effects of vibrations [2].

Factors Affecting Human Vibration Comfort

Several factors influence how individuals perceive and experience whole-body vibrations. These factors can be broadly categorized into personal, physiological, and environmental aspects. Personal factors include age, gender, body weight, and overall fitness. Physiological factors involve individual susceptibility to motion sickness or other conditions. Environmental factors encompass noise, temperature, and lighting conditions. It is within this realm of environmental factors that the influence of vision becomes particularly relevant [3].

There are some studies where the body is considered as a single mass and the range of resonance frequencies is found according to the position of the body and the direction of vibration. When internal organs are taken into consideration, completely different results are found. The human body will have different resonance frequencies for its internal organs depending on the direction and position of the person subjected to the vibration stimulus. Several studies have been undertaken with the objective to obtain the dynamic response of human organs but some difficulties were present [4]. Such difficulties can be attributed to the fact that these studies used animals, dummies or even dead bodies instead of live people.

The Role of Vision in Vibration Comfort

Vision plays a crucial role in the human perception of motion and spatial orientation. When subjected to vibrations, visual cues provide essential information that helps the brain integrate sensory inputs and make sense of the motion [5]. The eyes track stationary objects, which allow the brain to distinguish between self-motion and external motion. This visual feedback complements the vestibular system's input and can significantly influence the overall perception of vibration comfort [6].

Visual Cues and Vibration Perception

The presence or absence of visual cues can modulate the human perception of whole-body vibrations. For example, when traveling in a vehicle, looking out the window and fixating on stable objects such as the horizon can enhance comfort levels. The brain interprets these visual cues as reference points and uses them to establish a stable frame of reference. This helps mitigate the sensations of motion and reduces discomfort [7].

On the other hand, environments with limited visual cues or confined spaces can exacerbate the perception of vibrations. In situations such as long-haul flights or driving through tunnels, where external visual references are scarce, the brain relies more heavily on vestibular inputs [8]. This heightened reliance on internal signals can amplify the sensations of motion, leading to increased discomfort.

Implications for Design and Ergonomics

Understanding the influence of vision on whole-body human vibration comfort levels has practical implications for various industries. Designers and engineers can take these insights into account to create environments, vehicles, and equipment that optimize comfort and reduce the potential negative effects of vibrations [9].

In transportation, for instance, the design of cabin interiors can incorporate visual features that provide stable references, such as wellplaced windows or strategically positioned displays. In workplaces, where machinery or equipment generates vibrations, optimizing the layout and positioning of workstations to offer visual stability can contribute to employee well-being [10,11].

While whole-body vibrations are an inevitable part of certain industries and daily life, the influence of vision on vibration comfort levels is often overlooked. By considering the role of visual cues and integrating them into design and ergonomic considerations, we can enhance the overall well-being of individuals exposed to vibrations. A holistic approach that combines physiological, personal, and environmental factors, including visual cues, will contribute to reducing discomfort, improving work efficiency, and ensuring healthier living conditions for individuals subjected to whole-body vibrations.

The vision results presented the same curve behavior found in previous studies considering gender, corporeal mass index and age, i.e., the sensibility decreased with the increase of frequency reaching a minimum between 40 Hz and 50 Hz and later increased again at 63 Hz, decreasing not as much as before at 80 Hz. This fact indicates that independently of the parameter under investigation, the volunteers adjust small acceleration levels for lower frequencies, and high acceleration levels for higher frequencies, although for the series of studies performed here there is a decrease in the acceleration levels above 50 Hz again. Despite the same behavior, the values obtained for each parameter was similar for the perception threshold, although differ for the maximum acceptable vibration limit. Around 40 and 60 Hz, the results may have been influenced by the resonant frequencies of the head and ocular globe. Also, at low frequencies, the setup used influenced the results obtained since there is vibration amplification at that region, making the subjects adjust smaller acceleration levels than at the high frequencies, where isolation occurs.

During the statistical analysis of the variable vision, no differences were found between the two groups studied. In spite of that, the average results for the covered eyes group were smaller than the average results for the uncovered eyes group. The fact of covering the eyes can be helping the subjects to be more concentrated, so making possible for them to notice the vibration of smaller intensity. However, the volunteers’ results for the covered eyes could have being influenced by previous knowledge of the tests as well, as the same sample that took part previously in other tests were used for the analysis of the uncovered eyes. For most of the participants there was a decrease in the answers. No repeatability analysis was undertaken to confirm this fact. New tests shall be accomplished to confirm these hypotheses.

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