Seitz Immanuel P, Jolly Jasleen K, Dominik Fischer M, Simunovic Matthew P
University Eye Hospital Tübingen, Elfriede-Aulhorn Straße 7, 72076, Tübingen, Germany.
Institute for Ophthalmic Research, Elfriede-Aulhorn Straße 7, 72076, Tübingen, Germany.
Graefes Arch Clin Exp Ophthalmol. 2018 Apr;256(4):665-673. doi: 10.1007/s00417-018-3921-0. Epub 2018 Feb 5.
The purpose of this study was to characterise alterations in colour discrimination in a cohort of patients with choroideremia prior to gene therapy, using a test previously validated for use in patients with retinal dystrophies.
We tested 20 eyes of 10 patients with a diagnosis of choroideremia and an age-matched cohort of 10 eyes of 10 normal controls using the "Cambridge Colour Test" (CCT), in which subjects are required to distinguish the gap in a C presented in one of 4 orientations in a Stilling-type array. Colour discrimination was probed along eight axes in the CIE Luv* colour space, and the resulting data were plotted in the CIE 1976 chromaticity diagram and fitted with least-squares ellipses. Subsequently, we estimated the achromatic area for each subject by calculating the area of the resultant discrimination ellipse and calculated sensitivity thresholds along relevant colour confusion axes.
Colour discrimination-as quantified by log of the ellipse area expressed in square 1/1000th units in CIE 1976-was 2.26 (range 1.82 to 2.67) for normal subjects and 3.85 (range 2.35 to 5.41) for choroideremia patients. There was a statistically significant correlation between both achromatic area and red-green colour discrimination at the CCT and BCVA, and to a lesser degree between blue colour discrimination at the CCT and BCVA. The majority of ellipses in choroideremia were aligned close to the tritan axis, and loss of sensitivity was significantly larger in the tritan direction than in the red-green.
The majority of our patients demonstrated greater loss in tritan discrimination than in red-green colour discrimination using the CCT. There was a significant correlation between achromatic area and BCVA. In keeping with our current understanding of the machinery of colour vision, there was a significant correlation between BCVA and colour discrimination thresholds, which was stronger for red-green colour discrimination, than for tritan colour discrimination. We propose that this and similar tests of colour discrimination may prove to be suitable tools for assessing functional outcomes in gene therapy trials for choroideremia.
本研究旨在利用一项先前已验证可用于视网膜营养不良患者的测试，对一群在接受基因治疗前的无脉络膜症患者的颜色辨别变化进行特征描述。
我们使用“剑桥颜色测试”（CCT）对10例诊断为无脉络膜症患者的20只眼睛以及年龄匹配的10名正常对照者的10只眼睛进行了测试。在该测试中，受试者需要辨别在斯蒂林型阵列中4种方向之一呈现的字母C中的缺口。沿着CIE Luv*颜色空间中的8个轴探测颜色辨别能力，并将所得数据绘制在CIE 1976色度图中，并用最小二乘椭圆拟合。随后，我们通过计算所得辨别椭圆的面积来估计每个受试者的消色差区域，并计算沿相关颜色混淆轴的敏感度阈值。
以CIE 1976中以千分之一平方单位表示的椭圆面积的对数来量化，正常受试者的颜色辨别能力为2.26（范围为1.82至2.67），无脉络膜症患者为3.85（范围为2.35至5.41）。在CCT中，消色差区域和红绿色颜色辨别能力与最佳矫正视力（BCVA）之间均存在统计学上的显著相关性，而在较小程度上，CCT中的蓝色颜色辨别能力与BCVA之间也存在相关性。无脉络膜症患者的大多数椭圆接近蓝黄色轴排列，并且在蓝黄色方向上的敏感度损失明显大于红绿色方向。
使用CCT，我们的大多数患者在蓝黄色辨别方面的损失大于红绿色辨别。消色差区域与BCVA之间存在显著相关性。与我们目前对色觉机制的理解一致，BCVA与颜色辨别阈值之间存在显著相关性，红绿色颜色辨别比蓝黄色颜色辨别更强。我们认为，这种及类似的颜色辨别测试可能被证明是评估无脉络膜症基因治疗试验功能结果的合适工具。
