Crying often makes eyes appear brighter, although the exact effect varies among individuals and eye colors. This isn't a change in actual eye color but rather an alteration in how light reflects off the eye.
The Role of Water and Light Reflection
The increased brightness is primarily due to the presence of tears. Tears increase the moisture content around the eyes, which changes the way light interacts with the iris and sclera (the white part of the eye). As noted on Reddit (https://www.reddit.com/r/AskReddit/comments/chpvs8/why_do_hazel_eyes_turn_green_when_you_cry_does/), water affects light refraction, leading to a perceived color shift or intensified brightness. The added moisture can also make the sclera appear whiter, providing a higher contrast against the iris, which in turn makes the eye color appear more vibrant. This is similar to how a wet surface reflects light differently than a dry surface.
Blood Vessels and Perceived Color Change
While tears are the main contributor, other factors can play a secondary role. Some sources mention changes in blood pressure and flow affecting eye color (https://www.quora.com/My-usually-green-eyes-become-a-very-bright-emerald-green-after-crying-No-redness-just-a-dazzling-green-Have-you-ever-noticed-a-similar-change). However, the effect of this on brightness is likely less significant than the impact of tears. Although crying can sometimes cause redness in the eyes, this isn't the primary cause of increased brightness. The reference states that when crying, "your eyes obtain a reddish color, making your eyes appear brighter." This suggests that while redness is present, the overall effect is still perceived as brighter.
Individual Variations
The extent to which eyes appear brighter after crying varies significantly. Factors such as natural eye color, the amount of moisture produced, and individual differences in iris structure influence the observable effect. For instance, someone with lighter colored eyes might see a more dramatic change than someone with darker eyes.
Conclusion
In short, the increased brightness observed after crying stems mainly from the alteration in light reflection caused by tears. This effect enhances the vibrancy of the eye color, making them appear brighter, rather than a true color change.
