i had an eye appointment today, just to check your cataracts i think and other stuff
I have cross eyes, and to get surgery and stitches on my right eye when I was 5. I have been to eye doctors for most of my life.
They dialate your eyes so the pupil opens up and they can see inside of it to make sure everything is ok, cataract checking is a different process, but dilation is a way to make sure that you are in good shape in your eye, that's why they shine a light in you eye after dialation, to make sure your nerves and muscles are looking good!
Dialation

Now, checking for glaucoma and cataracts is a different process that involves checking the pressure of your eyes, the doctors put this yellowish substance into your eyes and make you rest your head on this thing while the doctor shines a blue light and this magnifying glass thing comes really close to your eye and the doctor puffs a little bit of air to check the pressure. The first time I did it, it was scary as hell, but I got over it
The Machine and what it does