Feedback means that the output from a device is fed back to it as new input. You can feed input to a retina, but cannot take its output.
You will get no feedback if the microphone is not linked to a speaker, or cannot hear the speaker.
You will get no feedback if the video camera is not pointing to the display.
Your eye consumes input, but this input is only used to change the state of your brain in mysterious ways. No output is produced. There is no "Kodak" organ in the human body which reproduces with fidelity the image seen by the retina*. Without output, there is nothing to feed back - same as how you can't get feedback when a camera is not linked to a display. A display, with human beings, would be analogous to a magic machine that reads your mind.
If you looked at your retina, you'd see your retina. Just like a camera pointed at a mirror would see a camera.
The closest thing you can do is imagine yourself, imagining yourself, imagining yourself... Although you would probably need to take mind-altering substances to experience this fully.
*: I say no organ exists, but it is possible for humans to reproduce an image they've seen. It's called "painting". Some famous painters apparently have included an image of themselves in their picture, depicted while painting the picture.
This isn't really a classical painting, but to give an example:
The trouble is that actually painting a picture takes a long time, so the feedback is very slow - each iteration may take days.