Yes close the eyes tightly ... but don't stop trying to see because you are using your actual vision. That's why the room has to be very bright... so bright that light passes through your thumbs/thumbnails into your retina. It might actually be optimal to do this while sitting at a picnic table outside while facing the sun. The back of the thumnails are used to create a slight 'dent' in both eyeballs at the same time... you'll only end up using one eye or the other ... but this will give you two chances of success instead of one. Apply slight pressure with the back of the thumb until you make out anyf sort of persistent visual phenomena. You aren't looking for hypnagogia or some such thing but an actual real world visual impression. When you have something to look at ... vary the amount of pressure on the eyeballs to bring it into greater focus. If i were to draw what i have seen it would be just the same as what you can see in any textbook containing pictures of cells and such under the microscope. I have seen cells within my own body at magnifications of anywhere between 10x and 1000x. It can be done. Good luck.