Here in British Columbia we don’t have a wide variety of snake species, and the Gulf Islands where I live are almost entirely dominated by a single species the Garter Snake and an occasional glimse of the rare Sharp-tailed Snake.
Although Garter Snakes come in a wide variety of colours their eyes are not normally blue.
In the example below the snake, found in my garden here on Gabriola Island, has blue eyes, worthy of a computer generated film monster. However in this case the blue colouring is caused by the snake preparing to shed it’s skin. A layer of moisture builds up between the old skin and the new, causing the intense blue look.
I selected a fairly wide aperture for this shot as I wanted to concentrate attention on the blue eyes and head of the snake.

Garter snake preparing to shed skin
Nikon D3, 105mm f2.8 VR micro lens, ISO 400, 1/125th sec @ f5.0, hand held.