I’m reading a novel in which a character’s eyes flash — a lot.

Human eyes in fiction do other amazing things, such as sparkle, glow, smoulder and dance.

Only they can’t. Think about it. “Flash” is a verb meaning to emit short bursts of light. Eyes can’t emit light, only reflect it. The eyes of some animals contain reflective tissue called tapetum lucidum, which is why they appear to shine in the dark — but only in the presence of light sources such as headlights, flashlights or firelight. They don’t shine in pitch darkness. Short bursts of reflected light may be described as flashes, but human eyes can’t do that either.

It’s also impossible for eyes to sparkle or glow, phenomena in which light is created by the thing doing the sparkling or glowing. Eyes do not have internal combustion, even when a character is enraged or ecstatic.

As for dancing, the only eyes that can literally do that are ones on stalks. “Dancing eyes” is a phrase used to describe a situation where someone is smiling or laughing — actions which flex the facial muscles — and moving their eyes around as well, looking from one person to another in a state of happy animation.

Eyes are such important features, both for experiencing the world and expressing emotion, it’s inevitable that writers pay attention to them. And of course the phrases I’ve mentioned, such as eyes that dance or smoulder, are really metaphors. If writers never used metaphors or similes and always stuck to the literal, writing would lose much of its life and colour.

But as with so many other areas of writing, it’s a matter of degree. One incidence of flashing eyes may be fine, but when characters are flashing at each other like a couple of lighthouses, I’m diverted from the narrative. I start counting incidences of flashing eyes. I start reading the prose, not the story.

Many of these eye-related words and phrases are also cliches, and while cliches can be useful shortcuts, using too many of them is a sign of lazy writing.

Going back to the flashing eyes as an example — what is it that I’m trying to show when I use this phrase? Obviously not bursts of light coming from someone’s eyes (unless the character is a robot or someone with supernatural light-emitting powers). If I stop and visualize what my character is doing, I see them sending a quick glance toward another person, often with a facial expression that conveys anger or annoyance. How else can I express this? How about: “A glance like a thrown knife,” or “He darted me a narrow-eyed glance,” or “A look that made me wish for a catcher’s mask and mitt.”

Whatever I choose — simile, metaphor or simple description — I aim for a frictionless reading experience. Word combinations that are too clever are just as distracting as overused cliches. I have to remind myself I’m not trying to score points for originality or cleverness, just keep the reader engaged with the story I’m telling. If I get it right, the reader will subconsciously register my colourful prose without losing the narrative thread. After they finish the book, they’ll say, “That was a great read!” without realizing precisely why. And that will make my eyes light up and dance.