Eye Vision: Focusing & Accommodation (2D)

Object

Distance to object 6.0

Pupil diameter 0.12

Eye condition

Normal

Myopia

Hyperopia

Accommodation

Manual accommodation 0.70

Eye condition: normal.

Live Readout

Focus point

–

Optical power

–

Image sharpness

How it works

Light from the object enters through the transparent cornea, passes through the pupil (an aperture in the iris), and is bent again by the crystalline lens. The cornea supplies roughly two-thirds of the eye's fixed refractive power; the lens supplies the rest and, uniquely, can change shape.

Accommodation is the ciliary muscle squeezing the lens into a rounder, more powerful shape to focus on near objects, and relaxing it flat for distant ones — the yellow lens in the diagram visibly thickens as you move the object closer or raise manual accommodation.

In myopia (short eyeball, too long axially) light converges before reaching the retina; in hyperopia (too short) it would converge behind it. Toggling Glasses adds a corrective lens in front of the eye — diverging for myopia, converging for hyperopia — that shifts the focus point exactly back onto the retina.

The three yellow rays leaving the object's tip all bend at the lens plane and meet (or fail to meet) at the focus point; the green ring on the retina shows the resulting blur circle — the wider the ring, the blurrier the image, exactly as summarized by the sharpness bar.