Oh no! Something scratched the front of your lens? Don’t worry. It’s not that bad.
Your lens has something called a “minimum focusing distance.” This means the lens can only focus on something that’s at least a bit away from it – for most lenses, this could be something like 6 inches (15cm). It’s often much further away.
When something is really close to your lens, it becomes very out of focus. When it’s on your lens, it’s extremely out of focus. This means that anything close to your lens is so blurred out, that it hardly affects the image.
Here’s a good example, clearly shot through a chain link fence:
It’s easy to see the pattern from the chain link fence. But it really doesn’t affect the ability to see the bald eagle. Look – a part of the fence clearly went right through the eagle’s face. Let’s zoom in.
If you can hardly notice a thick, metal fence – is that tiny, narrow scratch going to really change things that much? Not really.
That said, you will have reduced contrast and increased chance of lens flares. It’s not good… it’s just not awful, either.
And if you don’t believe me, check with the experts. Here’s a post with the always-excellent LensRentals.com that shows how little it matters.