Can Everyone Cross Their Eyes?
Not everyone can cross their eyes on command, but most people with normal binocular vision can bring both eyes inward briefly when looking at something close. This inward movement is called convergence, and it's part of the near-focus response, where the eyes turn inward, the lens changes shape, and the pupils constrict so you can focus on close objects. Difficulty doing this can happen when the eyes don't team together well; convergence insufficiency affects about 7.5% of the population in one clinical review, while one school-age study found definite convergence insufficiency in 5.3% of children ages 6 to 14.
Crossing your eyes for fun is different from strabismus, a medical eye-misalignment condition that affects roughly 2% to 4% of children. Occasional voluntary eye crossing usually isn't a concern, but eyes that turn inward or outward without control, double vision, headaches, or trouble focusing up close are signs you should get an eye exam.
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