Maddess T, Severt W L
Visual Sciences Group, Research School of Biological Sciences, Australian National University, Canberra, ACT.
Aust N Z J Ophthalmol. 1999 Jun-Aug;27(3-4):194-6. doi: 10.1046/j.1440-1606.1999.00195.x.
The frequency doubling (FD) illusion is the basis for new diagnostic methods for glaucoma. The FD illusion is seen when low spatial frequency grating patterns are contrast modulated at high rates. The present experiments examined which spatial frequencies might be optimal and whether high flicker rates are required.
We determined contrast thresholds for the following: W1, a wide-field 0.25 c/deg grating at 27 Hz contrast reversal; W2, as W1 but no flicker; MAC, 27 Hz, 4 c/deg grating presented to the central 4 degrees; and E1 to E7, seven spatial frequencies in the range 0.063-0.813 c/deg, 27 Hz, presented in a 5 degrees aperture at 15 degrees (nasal) eccentricity.
W1 was the best predictor of glaucoma. Of the eccentrically presented stimuli, E6 (0.688 c/deg) was the best predictor of glaucoma while the lower spatial frequencies performed less well. Only MAC was significantly age-dependent.
倍频（FD）错觉是青光眼新诊断方法的基础。当低空间频率光栅图案以高频率进行对比度调制时会出现FD错觉。本实验研究了哪些空间频率可能是最佳的，以及是否需要高闪烁频率。
我们确定了以下各项的对比度阈值：W1，一个在27Hz对比度反转下的宽视野0.25 c/deg光栅；W2，与W1相同但无闪烁；MAC，在中央4度呈现的27Hz、4 c/deg光栅；以及E1至E7，在0.063 - 0.813 c/deg范围内的七个空间频率，27Hz，在15度（鼻侧）偏心度的5度孔径中呈现。
W1是青光眼的最佳预测指标。在偏心呈现的刺激中，E6（0.688 c/deg）是青光眼的最佳预测指标，而较低的空间频率表现较差。只有MAC显著依赖于年龄。
