Subjective visual vertical with the bucket method in Brazilian healthy individuals

ABSTRACT INTRODUCTION: The capacity of a healthy individual to estimate the true vertical in relation to the Earth when a fluorescent line is aligned in a completely dark room is called the subjective visual vertical. OBJECTIVE: To evaluate subjective visual vertical using the bucket method in healthy Brazilian individuals. METHODS: Binocular subjective visual vertical was measured in 100 healthy volunteers, 50 females and 50 males. The volunteers indicated the estimated position in which a fluorescent line inside a bucket reached the vertical position. A total of ten repetitions were performed, five clockwise and five counterclockwise. Data were tabulated and analyzed statistically. RESULTS: It was observed that the highest concentration of absolute values of vertical deviation was present up to 3°, regardless of gender, and the vertical deviation did not increase with age. The analysis of the mean of the absolute values of deviations from the vertical of 90% of the sample showed a maximum value of 2.6°, and at the analysis of 95%, the maximum value was 3.4° deviation from the vertical. CONCLUSION: The bucket method is easy to perform and interpret when assessing the deviation of the subjective visual vertical in relation to the true vertical in healthy Brazilian individuals.

### 摘要与引言
健康个体在完全黑暗的房间内将荧光线对齐时，估算相对于地球的真实垂直方向的能力，被定义为主观视觉垂直（subjective visual vertical）。

### 研究目的
采用桶法（bucket method）评估健康巴西人群的主观视觉垂直水平。

### 研究方法
本研究纳入100名健康志愿者，其中女性50名、男性50名，对受试者的双眼主观视觉垂直进行检测。志愿者需调整桶内荧光线的位置，使其视觉上呈现垂直状态。实验共开展10次重复测试，包含5次顺时针调整与5次逆时针调整。对采集的数据进行制表并开展统计学分析。

### 研究结果
观察发现，无论受试者性别如何，垂直偏差绝对值的最高集中区间均在3°以内，且垂直偏差未随年龄增长而增大。对90%受试者的垂直偏差绝对值均值进行分析，其最大值为2.6°；针对95%受试者的分析结果显示，最大垂直偏差值为3.4°。

### 研究结论
在健康巴西人群中评估主观视觉垂直与真实垂直方向的偏差时，桶法操作简便且易于解读。