Crests
Yes, they can really see!
The american silkie is known of their huge crests and first people ask when they see them "can they really see?" Answer is it depends on individual.
Some girls can go without a single trim and see perfectly fine, while others will actully get depressed when they can not see.
Most often its only the feathers under the eye that is in the way for the sight. In my bigger crested girls I do take more infront and above the eye, but I try to avoid this.
My experience: I use a scissors made for dogpaws to trim around my silkies eyes. These are shorter and have rounded edges. This makes it much easier to trim!I have a girl that have had a small crest basicly her whole life. When suddenly after a hard molt she got a HUGE one. While I tought this crest was beautiful, I noitced something diffrent with her. She was basicly standing still, not jumping from the perch. I knew that hens can have trouble seeing with their crest and since she was not use to having a big crest. I came to a conclusion, she was depressed due to lack of sight. I tried this theory with putting her crest in a bun. She became a diffrent hen! Since some members of my crew like to eat hair ties, I gave a trim instead.