Knötzele Jessica, Heinrich Sven P
Eye Center, Medical Center and Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany.
Doc Ophthalmol. 2019 Oct;139(2):161-168. doi: 10.1007/s10633-019-09700-y. Epub 2019 Jun 3.
It is desirable to make VEP-based acuity estimates match standard subjective acuity numerically, as the latter is familiar to ophthalmologists and optometrists. This is achieved by applying an empirical conversion factor, and previous studies found the resulting values to be within ±1 octave of subjective acuity. This leaves room for improvement. In the present study, we tested for the case of a monocular acuity deficit whether the known difference between subjective and objective acuity in the trusted fellow eye can be used to get a more precise objective estimate in the eye of which the acuity is to be estimated. In other words, we tested whether it would make sense to determine a patient-specific conversion factor.
In 19 subjects, we obtained monocular objective and subjective acuity estimates with both eyes. Normal vision and artificially degraded vision were tested. Subjective acuity was taken as the veridical value. We computed the differences between objective and subjective acuity and reasoned that if these were correlated between eyes and acuity levels, the valid information from the trusted healthy eye could be used to improve the precision of the acuity estimate in the other, potentially impaired, eye.
The difference between objective and subjective acuity values was neither correlated significantly between eyes, nor was it correlated significantly between acuity levels.
Knowledge about the discrepancy between objective and subjective acuity values in one eye does not help improving the accuracy of acuity estimates in the other eye. The lack of a significant correlation between eyes even at the same acuity level suggests that a major part of the discrepancies between subjective acuity and VEP-based acuity is not the result of factors that would equally apply to both eyes, such as cortical morphology.
由于眼科医生和验光师对标准主观视力更为熟悉，因此希望基于视觉诱发电位（VEP）的视力估计值在数值上与标准主观视力相匹配。这可通过应用一个经验转换因子来实现，先前的研究发现所得值在主观视力的±1倍频程范围内。这仍有改进空间。在本研究中，我们针对单眼视力缺陷的情况进行测试，即能否利用可靠的对侧眼已知的主观和客观视力差异，来更精确地估计患眼的视力。换句话说，我们测试确定一个针对患者的转换因子是否有意义。
我们对19名受试者的双眼进行了单眼客观和主观视力估计。测试了正常视力和人工降低的视力。主观视力被视为真实值。我们计算了客观和主观视力之间的差异，并推断如果这些差异在双眼和视力水平之间具有相关性，那么来自可靠健康眼的有效信息可用于提高对另一眼（可能受损）视力估计的精度。
客观和主观视力值之间的差异在双眼之间以及在视力水平之间均无显著相关性。
关于一只眼睛中客观和主观视力值差异的知识无助于提高另一只眼睛视力估计的准确性。即使在相同视力水平下双眼之间缺乏显著相关性，这表明主观视力和基于VEP的视力之间差异的主要部分并非由同样适用于双眼的因素导致，例如皮质形态。
