History · 6 min read
The evolution of vision correction.
From reading stones to progressive lenses to software: eight centuries of moving the correction closer to the image.
The earliest near-vision aid was a polished lump of glass laid directly on the page. Reading stones magnified text without any frame at all; the correction sat on the paper, not on the reader.
Spectacles moved the lens to the face and stayed there for seven hundred years, growing more sophisticated — bifocals, then progressive lenses that grade smoothly from distance to near — but never changing the basic arrangement.
Contact lenses and refractive surgery moved the correction onto and into the eye itself. Each step brought the optics closer to the retina, and each traded convenience against invasiveness.
Software correction reverses the direction of travel: instead of altering the eye, it alters the image before it leaves the screen. The display already knows exactly what it is showing, which makes it the one surface in the chain that can compensate in real time.