Looking inside your own eye
They’re called entoptic phenomena – situations and experiences that give us a glimpse of what lies inside our own eyes. My two favourites:
Watching your own white blood cells fly through your retinal blood vessels.
The best way to see the blood cells coursing through your retinal blood vessels is to lie on your back looking up at a deep blue sky (not a bad experience in itself). After looking up for a while and focussing on nothing in particular, you’ll become aware of tiny white flicky dots all over your field of vision. (You’ll see other stuff as well, like floaters). Watch them for as long as you like.
See the layer of tears on the front of your eye ripple as you blink.
You need a bit more of a set-up for this one – either:
- a strong + or – lens held up close to the eye looking at a dot source of light (NOT laser!) in a dark room.
- observing while holding up really close to you a light reflected in a small spherical object -
- eg hold a ball point pen up close to your eye and adjust its position so that you are observing the (blurry) reflection of a light bulb.
- for those with glasses, you can do the same lining up the reflection of a light source on a droplet of water on your glasses lens.
This gives you a picture of all the irregularities in the optics of your eye – floaters, even cataracts, can be visualised this way. But the best bit is watching your own tear film – the thin layer of tears on the front of your cornea. Do a series of squeezy half-blinks, and you will see the tidemarks, the ‘ripples’ if you like, of the effect of the eyelids on the tear film. Or hold your eyes open wide (like in the stare-you-out game) and watch spots, lines and blobs appear as the tears dry off the front of your eye. Or massage your lower eyelid a little, and prepare to observe oil from the glands in the lid mixing in with the tear film.
Have fun looking inside your own eyes…
