Purpose

An orientation-specific visual evoked potential (osVEP) protocol was developed to probe meridional anisotropies in children with refractive amblyopia. The aim was to characterise the osVEP response in children with bilateral refractive amblyopia, evaluate the intra-session repeatability of the main osVEP components (C1, C2 and C3), coefficient of repeatability (CoR) of the response to gratings in different meridians and determine if refractive amblyopes have poorer repeatability as compared with non-amblyopic controls.

Methods

Children aged 4–7 years with newly diagnosed and untreated bilateral refractive amblyopia and non-amblyopic controls were recruited. Orientation-specific pattern-onset VEPs were recorded in response to an achromatic sinewave grating stimulus of 4 cycles per degree under monocular and binocular stimulation. The grating lines used for monocular stimulation were parallel with the subjects’ most positive and negative astigmatic meridians when considered in sphero-minus cylinder form (Meridians 1 and 2, respectively). In subjects without astigmatism, meridians 1 and 2 were designated horizontal and vertical gratings, respectively. Binocular stimuli were presented with grating lines parallel to meridians 45, 90, 135 and 180°. The repeatability of latencies of the main osVEP components (C1, C2 and C3) were investigated using two successive osVEPs recordings for each stimulus meridian and the CoR for each component’s latencies were assessed.

Results

Seven amblyopic children (Visual acuity (VA) ranging from 0.08 to 0.40 LogMAR in the less amblyopic eye and 0.26–0.52 LogMAR in the more amblyopic eye) and 7 non-amblyopic controls (VA ranging from 0.00 to 0.02 LogMAR in either eye), with a median age of 4.6 and 7.0 years, respectively, completed the study. C1 had the highest CoR for most conditions assessed. Ratio of CoRs C1:C2 was > 2 for all binocular meridians in controls and the 90 and 180 meridians in the amblyopes; C1:C3 was > 2 for the binocularly assessed 45, 90 and 135 meridians in the controls and the 90 and 180 meridians in the amblyopes; C2:C3 were all < 2 for all meridians assessed in both groups.

Conclusions

The osVEP waveforms are reliable and useful for future investigations into the meridional anisotropies in children with refractive amblyopia, particularly the C3 component. Component C1 had the poorest repeatability, which consequentially affected C2 amplitude estimation. Only C3 amplitude and latency could be consistently estimated as C2 and C3 latencies were similarly repeatable. Coefficients of repeatability of osVEP latencies did not appear to systematically differ between non-amblyopic and amblyopic children.

中文翻译：

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表征双侧屈光性弱视和非弱视对照儿童的定向特定模式起始视觉诱发电位。

目的

开发了一种定向特定视觉诱发电位 (osVEP) 协议来探测屈光性弱视儿童的经向各向异性。目的是表征双侧屈光性弱视儿童的 osVEP 响应，评估主要 osVEP 组件（C1、C2 和 C3）的会话内可重复性、对不同子午线光栅响应的可重复性系数 (CoR) 并确定如果与非弱视对照相比，屈光性弱视的重复性较差。

方法

招募了新诊断和未经治疗的双侧屈光性弱视和非弱视对照的 4-7 岁儿童。在单眼和双眼刺激下，每度 4 个周期的消色差正弦波光栅刺激下记录定向特定模式起始 VEP。当以球负圆柱形式（分别为子午线 1 和 2）考虑时，用于单眼刺激的光栅线与受试者的最大正负散光子午线平行。在没有散光的受试者中，子午线 1 和 2 分别被指定为水平和垂直光栅。双目刺激呈现平行于子午线 45、90、135 和 180° 的光栅线。主要 osVEP 组件（C1，

结果

7 名弱视儿童（弱视眼的视力 (VA) 范围为 0.08 至 0.40 LogMAR，弱视眼为 0.26-0.52 LogMAR）和 7 名非弱视儿童（每只眼睛的视力 (VA) 范围为 0.00 至 0.02 LogMAR），中位年龄分别为 4.6 岁和 7.0 岁的人完成了这项研究。对于大多数评估条件，C1 具有最高的 CoR。对于对照中的所有双眼经络以及弱视中的 90 和 180 经络，CoRs C1:C2 的比率 > 2；C1:C3 > 2 对于双眼评估的对照组中的 45、90 和 135 条经络以及弱视中的 90 和 180 条经络；两组中评估的所有经络的 C2:C3 均 < 2。

结论

osVEP 波形对于未来研究屈光性弱视儿童的经向各向异性，尤其是 C3 分量是可靠的和有用的。分量 C1 的可重复性最差，从而影响 C2 幅度估计。由于 C2 和 C3 延迟具有类似的可重复性，因此只能一致地估计 C3 振幅和延迟。osVEP 潜伏期的可重复性系数在非弱视和弱视儿童之间似乎没有系统性差异。