Eyes with the corneal ectasia keratoconus have performed better than expected (e.g. visual acuity) given their elevated levels of higher-order aberrations that cause rotationally asymmetric retinal blur. Adapted neural processing has been suggested as an explanation but has not been measured across multiple meridional orientations. Using a custom Maxwellian-view laser interferometer to bypass ocular optics, sinusoidal grating neural contrast sensitivity was measured in six eyes (three subjects) with keratoconus and four typical eyes (two subjects) at six spatial frequencies and eight orientations using a two-interval forced-choice paradigm. Total measurement duration was 24 to 28 hours per subject. Neural contrast sensitivity functions of typical eyes agreed with literature and generally showed the oblique effect on a linear-scale and rotational symmetry on a log-scale (rotational symmetry was quantified as the ratio of the minor and major radii of an ellipse fit to all orientations within each spatial frequency; typical eye mean 0.93, median 0.93; where a circle = 1). Mean sensitivities of eyes with keratoconus were 20% to 60% lower (at lower and higher spatial frequencies respectively) than typical eyes. Orientation-specific neural contrast sensitivity functions in keratoconus showed substantial rotational asymmetry (ellipse radii ratio: mean 0.84; median 0.86) and large meridional reductions. The visual image quality metric VSX was used with a permutation test to combine the asymmetric optical aberrations of the eyes with keratoconus and their measured asymmetric neural functions, which illustrated how the neural sensitivities generally mitigated the detrimental effects of the optics.

患有圆锥角膜的眼睛的高阶像差水平升高，导致旋转不对称的视网膜模糊，其表现比预期要好（例如视力）。适应性神经处理已被建议作为一种解释，但尚未在多个经向方向上进行测量。使用定制的麦克斯韦视图激光干涉仪绕过眼部光学器件，使用两间隔强制测量在六只眼睛（三名受试者）和四只典型眼睛（两名受试者）的圆锥角膜和八个方向的六个空间频率和八个方向上测量正弦光栅神经对比敏感度-选择范式。每个受试者的总测量持续时间为 24 至 28 小时。典型眼睛的神经对比敏感度函数与文献一致，并且通常显示出线性尺度上的倾斜效应和对数尺度上的旋转对称性（旋转对称性被量化为适合所有方向的椭圆的短半径和长半径的比率）在每个空间频率内；典型眼均值 0.93，中值 0.93；其中圆圈 = 1）。圆锥角膜眼睛的平均敏感度比典型眼睛低 20% 至 60%（分别在较低和较高的空间频率下）。圆锥角膜的方向特异性神经对比敏感度函数显示出显着的旋转不对称性（椭圆半径比：平均值 0.84；中值 0.86）和较大的子午线减小。视觉图像质量指标 VSX 与排列测试结合使用，将圆锥角膜眼睛的不对称光学像差及其测量的不对称神经功能结合起来，这说明了神经敏感性通常如何减轻光学的有害影响。