Refractive errors: myopia, hypermetropia, astigmatism, presbyopia
Ophthalmology · MBBS
Eye anatomy lab
Interactive 3DFollow light through the eye — see how myopia and hypermetropia miss the retina.
Controls
Drag the sliders or type a value — the simulation updates live.
Study notes
A 10-year-old can't read the blackboard — myopia; concave glasses sharpen distance. Myopia (long eyeball — parallel rays focus before retina: distant blur, near fine; concave/minus lens diverges rays onto retina): children's commonest — outdoor time slows progression. Hypermetropia (short — focus behind; convex/plus lens; children accommodate — strain/headache). Astigmatism (irregular cornea — distorted at all distances; cylindrical lens). Presbyopia (aging lens — after 40, near blur; reading glasses/bifocals). The blackboard blur is geometry — eyeball length vs focusing power mismatch.