Jacob Nikhita, Kamath Vandana, Sanjay B N
Assistant Professor, Sankara College of Optometry, Sankara Academy of Vision, Bangalore, India.
Optometrist, Sankara College of Optometry, Sankara Academy of Vision, Bangalore, India.
Br Ir Orthopt J. 2024 Jul 16;20(1):165-170. doi: 10.22599/bioj.365. eCollection 2024.
Dynamic visual acuity (DVA) is a complex visual function that requires the observer to detect a moving target, to visually acquire it by eye movements, and to resolve critical details contained in it, in a relatively brief time exposure. Dynamic contrast sensitivity (DCS) functions are determined over a range of angular velocities to complement the traditional contrast sensitivity (CS) functions (obtained with stationary targets).
A new chart is constructed to assess DCS by chosen 5×5 grid and Sloan letters (D, H, N, U, V, R, Z, S, K, O, C). Letters are constructed at a constant visual acuity of six lines having the contrast varied at each interval of the line. Each line has six letters and each line subtends different contrast (0.20 logCS-1.70 logCS). The chart has a motor of 45 revolutions per minute (rpm) and 30 rpm and measured among the normal population of the age group of 17 to 30.
Results shows that CS declines once the target stimulus is in motion. There was a statistically significant difference (p < 0.05) between the stimulus speeds of 30 rpm and 45 rpm. Dynamic contrast sensitivity values increased for lower target velocity indicating that as speed of the target stimulus increases, CS decreases.
This study concludes that the DCS decreases as the velocity increases. Consequently, incorporating the DCS chart into comprehensive eye examinations provides a holistic understanding of an individual's visual function.
动态视敏度（DVA）是一种复杂的视觉功能，要求观察者在相对较短的时间曝光内检测移动目标，通过眼球运动进行视觉捕捉，并分辨其中包含的关键细节。动态对比敏感度（DCS）函数是在一系列角速度范围内测定的，以补充传统对比敏感度（CS）函数（通过静止目标获得）。
构建了一种新图表，通过选定的5×5网格和斯隆字母（D、H、N、U、V、R、Z、S、K、O、C）来评估DCS。字母以恒定的六行视敏度构建，每行的对比度在每个间隔处变化。每行有六个字母，每行对应不同的对比度（0.20 logCS - 1.70 logCS）。该图表有一个每分钟45转（rpm）和30转的电机，并在17至30岁的正常人群中进行测量。
结果表明，一旦目标刺激移动，CS就会下降。30 rpm和45 rpm的刺激速度之间存在统计学显著差异（p < 0.05）。较低目标速度下的动态对比敏感度值增加，表明随着目标刺激速度的增加，CS降低。
本研究得出结论，DCS随速度增加而降低。因此，将DCS图表纳入全面的眼科检查可提供对个体视觉功能的全面理解。
