In Christianity Today, Al Hsu writes:

Encouraged by a 25 percent-off coupon given to me by a friend, I went ahead and had [laser eye] surgery [to correct my vision]. ... It didn't quite take. ... My vision had been something like 20/400, and he was able to bring it to 20/40—tantalizingly close to clear vision, but still fuzzy. Then I happened to attend an InterVarsity Asian American staff conference. During corporate worship, I squinted to make out lyrics on the far wall. In one particular session, we sang "God of Justice ”:

Live to feed the hungry

Stand beside the broken

We must go

Stepping forward

Keep us from just singing

Move us into action

We must go

I closed my eyes as we repeated the chorus, praying that God would direct me. How might I move into action? The song cycled back to an earlier verse, and I opened my watering eyes. The lyrics on the screen shimmered slightly, then came crisply into focus. I could see. Clearly. Wow. I could read every word easily, without squinting.

Had God just healed me? ... I blinked several times, and my vision wavered back and forth. Clear, blurry, clear, blurry. Then I realized what was happening. While singing I had been tearing up, moved by God's call, and the thin layer of water on my eyeballs functioned like contact lenses. The tears had been making my vision clearer. ... I suspect that I will never see as clearly as I do when I have tears in my eyes.