Every sandbox
Filter by domain, search, or sort. The domains are just a way in — nothing here is locked or ranked.
Astigmatism & the Conoid of Sturm
Two focal lines, the interval of Sturm, and the circle of least confusion.
Multiple Lens Systems
Build a system of up to three lenses and trace the image through each one.
Power Cross & Transposition
Convert between power cross and sphero-cyl, transpose, combine, and find the spherical equivalent.
Prisms & Prentice's Rule
Decentre a ray through a lens and watch the induced prism and its base.
Retinoscopy
Sweep the streak, read the reflex, find neutrality.
Thin Lenses & Image Formation
Drag the object, lens, and screen. Watch the image form, grow, and flip.
Vergence & Reduced Vergence
Step a wavefront through surfaces and watch vergence jump at each one.
soonA-Constant Optimization
Tune the lens constant and watch the outcome histogram slide.
soonAccommodation & the Near Response
Accommodative demand versus amplitude as the target nears.
soonBiometry Interpretation
Read a biometry printout and see how each value feeds the power.
soonCorneal Topography & Tomography
Placido and Scheimpflug maps; anterior and posterior elevation.
soonDuochrome
The red-green endpoint and the over-minus trap.
soonIOL Vergence Engine
Compare SRK/T, Hoffer Q, Holladay 1, and Haigis side by side.
soonJackson Cross-Cylinder & Cylinder Refinement
Refine cylinder axis and power; watch the power vector converge.
soonLight Adjustable Lens
Post-implant adjustment and custom light-distribution profiles.
soonPost-Refractive IOL Power
Why standard formulas fail post-LASIK, and the methods that fix it.
soonPremium IOL Selection
Match lens type to ocular and lifestyle factors (vendor-neutral).
soonPSF / MTF & Through-Focus
Image-quality metrics and the EDOF through-focus trade-off.
soonSchematic Eye Models
Switch between the reduced eye, Gullstrand, and Liou–Brennan.
soonSpherical Ametropia & Spectacle Correction
Far points, correcting lenses, and the effect of vertex distance.
soonThe Refractive Surprise
Trace a post-op surprise back to its cause.
soonToric IOL Planning & Rotational Misalignment
Plan cylinder and axis; rotate the lens and watch correction fall.
soonVisual Acuity & Optotype Design
Subtended angle, minimum angle of resolution, and where 20/20 comes from.
soonWavefront & Zernike Polynomials
Decompose an aberrated wavefront and see the retinal image respond.