retina

Etymology

From Middle English rethina, borrowing from Medieval Latin rētīna (“retina”, feminine noun), ellipsis of tunica rētīna (“net-like tunic”), used to describe the blood vessel system at the back of the eye. The phrase is attested in the 12th century in Guillelmus the abbot and Gerard of Cremona—the latter may have created this phrase as a translation for Arabic طَبَقَة شَبَكِيَّة (ṭabaqa šabakiyya) "net-like layer", which translates Ancient Greek ἀμφιβληστροειδής χῐτών (amphiblēstroeidḗs khitṓn, “retina”), which is attested in the ancient medical writer Galen.

noun

1. (ophthalmology) The thin layer of cells at the back of the eyeball that contains rods and cones sensitive to light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.