# Get Psyched Eye Lab — Original Right-Eye Teaching Model

Original geometry authored for Get Psyched, October 2026. No external anatomical mesh, AI anatomical object, texture, paid asset or account. No third-party geometry redistribution obligation. Existing Three.js dependency retains its own MIT license. The model preview is captured from this exact renderer, not a separately generated illustration.

Construction: concentric sculpted globe coats with corneal opening; transparent anterior corneal dome; radially varied iris annulus with actual central aperture; separate biconvex lens; ciliary ring and zonules; posterior retinal lining with separate foveal and optic-disc patches; a tubular nerve sheath exiting at the nasal disc; understated posterior vessels and vitreous space cue. Partial coats expose the temporal-side interior. Lens thickness and pupil aperture have separate state controls. The foveal depression and ciliary response are stylized rather than histological reconstructions. Retina thickness, vessel layout, iris fiber pattern and patch sizes are not patient measurements.

Right eye: anterior +X, superior +Y, temporal +Z. Optic disc is nasal (−Z) to fovea (+Z). The viewpoint may rotate; labels project from fixed model-space centers. The transparent dome is rendered as low-opacity physical material; opening pick geometry writes no color. Fovea and disc are separate patches on the posterior inner coat. No picture travels in the nerve.

Optics: reduced-eye, paraxial thin-lens equation 1/u+1/v=P. Whole-eye power combines cornea and lens into one effective plane positioned at the lens for the workbench. Retina distance 2.85 arbitrary units, object 6–30, aperture half-height0.30, object height0.6. Accommodation interpolates P between 1/2.85+1/30 and 1/2.85+1/6. Auto uses P=1/2.85+1/u. The corneal entry is schematic and passage through the pupil is straight. Retina distance represents a flat equivalent plane at x−1.90 although the anatomical lining is curved; off-axis endpoints can differ slightly from the lining. Ray convergence from the effective plane, retinal intercepts and preview blur share the calculation. Preview blur is 56×bundle half-width in model units, capped at9 CSS pixels. Manual percentage is not muscle effort, diopters or a prescription. Refractive examples hold object distance30 and relaxed power equal and use retinal distances2.85,3.35,2.35. Dashed beyond-retina lines are mathematical extensions.

Retina: generic slab light enters from vitreous through ganglion/bipolar layers toward photoreceptor outer segments; neural influence follows photoreceptor→bipolar→ganglion→nerve. Foveal inner layers are displaced in life, so this is not an exact foveal cross-section. Regional receptor drawings are schematic density, not measured counts. Bright/dim is an environment choice, not instant adaptation. The optional blind-spot marks remain displayed in all states.

References: College Board AP Psychology CED Topic1.6.B printed43–44; NEI How Eyes Work, About the Eye and Types of Refractive Errors; UTHealth Neuroscience Online section2 chapters14–15; OpenStax University Physics3 §2.4 Thin Lenses. See Sources and Model Assumptions in the Eye Lab for the source links and curriculum mapping. Anatomy beyond the CED supports instruction, not additional required memorization.

Display distances: the labeled object distance6–30 is used by the optical calculation. To keep both object and eye visible in the 3D viewer, its display position is compressed to X=2.9+(u−6)/24×1.2; the 2D drawing also compresses object distance. This display mapping does not change computed focus, retinal intercepts or blur. Neither the scene nor diagram is a clinical multi-surface ray trace.