視覺依賴的定義、評估與治療

Definition, Assessment and Treatment of Visual Dependence

李淑君(Shu-Chun Lee)

《台灣復健醫學雜誌》 45卷2期 (2017/12) Pp. 47-55

https://doi.org/10.6315/2017.45(2)01

摘要

正確的空間定向及姿勢平衡需要視覺、前庭覺和本體覺系統的整合，其中視覺在維持定向及平衡扮演了很重要的角色。如果視覺訊息正確，定向及平衡不受影響，然而若是靜態傾斜的框架或是動態旋轉的圓點等類似視覺訊息，則會產生負面影響。視覺依賴(visual dependence)是形容過度依賴視覺訊息的人，當他們在視覺訊息複雜、混亂或不正確的感覺環境下，像是走在繁忙的街道旁或是人多的超級市場裡，會迷失方向、失去平衡以及頭暈目眩的可能。阮柏氏測試(Romberg test)和感覺統合測試(Sensory Organization Test)主要評估視覺對姿勢控制下的影響，棒框測驗(Rod and Frame test)及棒盤測驗(Rod and Disc test)則是評估知覺方面的視覺依賴程度。然而造成視覺依賴的生理機制仍不清楚，過去認為可能與前庭覺或本體覺損傷有關，進一步研究指出前庭覺損傷可能較本體覺損傷更為影響。視覺依賴也被認為是一種感覺權重調整障礙(sensory reweighting deficit)，他們無法將不正確的視覺訊息減少，並彈性的把正確可靠的前庭或本體覺訊息放大。視覺依賴常發生在高齡者，其原因與周邊感覺系統老化有關，與年齡本身較無相關。退化的自我中心參考框架(egocentric frame of reference)也是造成視覺依賴的可能原因之一，因為視覺參考框架(visual frame of reference)代償性的變成主要判定身體姿勢位置的角色。視覺依賴需要許多注意力，因此瓜分了維持姿勢平衡所需的認知負載(cognitive loads)，而造成平衡不穩並提高跌倒的風險。視覺適應活動(visual habituation exercise)，例如視動刺激(optokinetic stimulation)訓練，是透過重複相同的視覺刺激，來增加視覺忍受度及降低視覺依賴的程度。然而，視覺依賴的治療活動其種類、強度、頻率和持續時間仍未定論，因此仍需更多的研究來解答。

關鍵字

評估(assessment) ； 機制(mechanism) ； 視覺(vision) ； 視覺依賴(visual dependence) ； 視覺適應活動(visual habituation exercise)

並列摘要

Effective orientation and balance are based on the integration of visual, vestibular, and proprioceptive sensory inputs. Vision plays a significant role in spatial orientation and posture maintenance; however, a static tilted frame or dynamic rotating visual disturbance can affect orientation and balance. Visual dependence (VD) is a term used to describe people who overly rely on visual information. Individuals with VD have difficulty in resolving situations wherein visual information is complex or inaccurate. They show greater postural instability and complain of incidences of dizziness and vertigo in sensory conflicting conditions, such as walking along the pavement or the aisle of a supermarket. The Romberg test and the Sensory Organization Test are commonly used to assess the influence of vision on postural control, whereas the Rod and Frame Test and Rod and Disc Test are used to evaluate VD levels at the perceptual level. However, VD mechanisms are still unclear. VD may be associated with vestibular or proprioceptive impairments. Recent studies have reported that VD is more likely to be affected by vestibular rather than proprioceptive inputs. VD is also considered to be a kind of sensory reweighting deficit. People with VD are unable to flexibly reduce the weighting of inaccurate input (vision) while increasing the weighting of input from the sensory systems (proprioceptive or vestibular systems) to provide more reliable information. VD is often reported in older adults; however, it may be due to the age-related decline of peripheral sensory systems and not due to aging as such. An impaired egocentric reference frame could be another contributing factor because the visual reference frame might compensate to become dominant in determining the orientation. VD needs more attentional demands that may share cognitive loads with the maintenance of balance; thus, it may increase postural instability and the risk of falls. Visual habituation exercise, such as optokinetic stimulation training, could increase tolerance in response to visual motion and decrease VD levels by using repeated presentation of the same visual stimuli. However, the type, intensity, frequency, and duration of treatment for VD are not conclusive; therefore, further investigation regarding rehabilitation exercises for VD is needed.

並列關鍵字

assessment ； mechanism ； vision ； visual dependence ； visual habituation exercise

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