Spanish 'ojo' and English 'eye' are estranged cousins: the same prehistoric root sent one down the Latin road and the other through Germanic, until the two no longer recognize each other by sound. Esperanto's 'okulo,' constructed from scratch in 1887, ended up the inadvertent sibling of 'ojo' — Zamenhof reaching for Latin as if continuity were a kind of universality. Chinese 眼 arrives from an entirely different history, without any Indo-European genealogy. Yet it carries something the alphabetic words cannot: 目, a pictogram of an eye, still nested inside the character after three millennia.
Old English ēage was two syllables; it contracted through Middle English to the modern monosyllable. The homophony of 'eye' and 'I' (first-person pronoun) is coincidental — the two words are etymologically unrelated.
Latin 'oculus' underwent syncope in Vulgar Latin (*oclus), then palatalization and further changes before yielding Old Spanish 'oio' and modern 'ojo.' The palindromic symmetry of o‑j‑o on the page mirrors the bilateral symmetry of the eye itself — coincidence, but a striking one.
目, the left half, is one of the oldest pictograms in Chinese script — oracle-bone inscriptions show a vertical oval with a horizontal pupil-line, the eye drawn face-on. Later scripts rotated it horizontal, and it became the semantic marker of scores of compounds. The right half, 艮, contributes sound rather than meaning, a reminder that even the most pictographic writing system must eventually borrow from the air.
In oracle-bone script (c. 1200 BCE), 目 stood upright — a wide oval with a line through its middle, the eye drawn as seen in a face. Subsequent scripts tipped it on its side as brushwork standardized. Today it survives as both a classical word for eye and as the semantic signal inside 眼 (eye), 盲 (blind), 眉 (eyebrow), and dozens of other characters.
目 (mù) is the classical and literary word for eye; 眼 (yǎn) is the vernacular form that predominates in modern speech. Both remain active: 眼睛 (eyes), 眼镜 (spectacles), 目标 (target / goal), 盲目 (blindly / without discernment).
Zamenhof sourced 'okulo' from Latin in keeping with his preference for internationally recognizable Greco-Latin roots. Productive derivatives: okulvitroj (spectacles, lit. eye-glasses), okula (adj. ocular), malfermi la okulojn (to open one's eyes, lit. and fig.).
In at least one language, the word for eye still contains a drawing of one.