retina
[C] Countable
pl: retinas
The term evokes the image of a biological sensor or a high-resolution screen. In medical contexts, it is treated with extreme delicacy because any separation from the eye wall results in immediate vision loss, giving the word a connotation of fragility and criticality. In modern technology, the word has been adopted to describe high-pixel-density displays. In this context, it suggests a level of clarity so extreme that the human eye cannot distinguish individual pixels, shifting the word from a biological organ to a benchmark for visual perfection.
Countable when referring to the specific organ in each eye, such as when a doctor examines a left or right retina.