Look carefully at the patterns, colors, and structure of reptile and amphibian eyes. You will be surprised by the beauty and variability. Snakes have no eyelids so the eye is round round. Amphibians and most lizards (exceptions geckos and night lizards) have eyelids and so may have round eyes or an ellipse from squinting.
Note the pupil shape. Some are round but you will also see horizontal and vertical pupils. Geckos have wild pupils.
The highlight and reflected light make the eye look wet or glossy. I often put the highlight at the border between the iris and the pupil to help show that it is reflecting off the surface above both the iris and the pupil.
The eyes from top left to bottom right: crocodile, viper, western toad, gecko, garter snake, newt, spadefoot toad, snake in process of shedding.