Department of Research, L V Prasad Eye Institute, Banjara Hills, Hyderabad, India.
Curr Eye Res. 2009 Dec;34(12):1030-5. doi: 10.3109/02713680903315771.
A shift from binocular summation to binocular inhibition has been observed when there is a significant decrease in contrast sensitivity or reduced retinal illuminance in one eye compared to the other as in cases of unilateral cataract and amblyopia. This study aims to determine how binocular function in post-LASIK subjects with unsatisfactory outcomes is influenced by differences between the two eyes in visual acuity and contrast sensitivity.
A retrospective analysis of monocular and binocular visual acuity (VA) and contrast sensitivity (CS) results was performed for 23 LASIK subjects who previously underwent a Functional Vision Test battery at Vision Sciences Research Corp. (San Ramon, CA). Photopic VA was measured with ETDRS chart and sine-wave grating CS was measured with FACT chart.
The difference between binocular and better monocular VA and CS was calculated for each subject and referred to as binocular difference. The interocular difference was calculated as better eye-worse eye for VA and CS. Significant negative correlations (P < 0.01) were observed between binocular difference and interocular difference for VA (r = -0.84) and CS at each spatial frequency of 1.5 (r = -0.90), 3 (r = -0.85), 6 (r = -0.79), 12 (r = -0.68), and 18c/d (r = -0.72). The greater the difference between the eyes, the lesser the binocular summation. Linear regression predicted a 1-line decrease in binocular summation for a 4-line increase in interocular acuity difference and a 35% decrease in binocular summation for a 50% increase in interocular difference of contrast sensitivity at 3c/d (ANOVA, P < 0.01).
Binocular inhibition in post-LASIK subjects increases as the visual sensitivity difference between the two eyes increases. Since the peak of human contrast sensitivity function is at the middle spatial frequencies, the decrease in binocular CS at 3c/d due to reduced CS in one eye is functionally significant.
当一只眼的对比敏感度或视网膜照度相对于另一只眼显著降低时，例如单侧白内障和弱视，会观察到从双眼叠加到双眼抑制的转变。本研究旨在确定 LASIK 术后双眼功能如何受到双眼视力和对比敏感度差异的影响。
对在 Vision Sciences Research Corp.（加利福尼亚州圣拉蒙）进行过功能视觉测试的 23 名 LASIK 术后患者的单眼和双眼视力（VA）和对比敏感度（CS）结果进行回顾性分析。明视 VA 用 ETDRS 图表测量，正弦光栅 CS 用 FACT 图表测量。
为每位患者计算双眼与较好单眼 VA 和 CS 的差异，并称为双眼差异。VA 和 CS 的双眼差异为好眼-差眼。明视 VA（r = -0.84）和 CS（r = -0.90）在 1.5、3、6、12 和 18c/d 各空间频率的双眼差异与眼间差异之间存在显著负相关（P < 0.01）。眼睛之间的差异越大，双眼叠加就越少。线性回归预测，眼间视力差异增加 4 行，双眼叠加减少 1 行，3c/d 的眼间 CS 差异增加 50%，双眼叠加减少 35%。（ANOVA，P < 0.01）。
LASIK 术后患者的双眼抑制随着双眼之间视觉敏感度差异的增加而增加。由于人类对比敏感度函数的峰值在中频，因此一只眼的 CS 降低导致 3c/d 处的双眼 CS 降低在功能上是显著的。
