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Aspheric eyeglass lenses allow for crisper vision than standard "best form" lenses, mostly when looking in other directions than the lens optical center. Moreover, the reduction of the magnification effect of a lens may help with prescriptions that have different powers in the 2 eyes ( anisometropia ).
t = center thickness (in metres); n = refractive index; P = front base curve (in 1/metres); h = vertex distance (in metres); F = back vertex power (in 1/metres), (essentially, the prescription for the lens, quoted in diopters ). If the difference between the eyes is up to 3 diopters, iseikonic lenses can compensate.
Aplanatic lens. An aplanatic lens is a lens that is free of both spherical and coma aberrations. [1] Aplanatic lenses can be made by combining two or three lens elements. [2] A single-element aplanatic lens is an aspheric lens whose surfaces are surfaces of revolution of a cartesian oval. [3]
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The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye 's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have ...
Aniseikonia can occur naturally or be induced by the correction of a refractive error, usually anisometropia (having significantly different refractive errors between each eye) or antimetropia (being myopic (nearsighted) in one eye and hyperopic (farsighted) in the other.)
Emmetropia is the state of vision in which a faraway object at infinity is in sharp focus with the ciliary muscle in a relaxed state. That condition of the normal eye is achieved when the refractive power of the cornea and eye lens and the axial length of the eye balance out, which focuses rays exactly on the retina, resulting in perfectly sharp distance vision.
Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits.
Gaussian functions are the Green's function for the (homogeneous and isotropic) diffusion equation (and to the heat equation, which is the same thing), a partial differential equation that describes the time evolution of a mass-density under diffusion.
Manipulating the cross differentiated Navier–Stokes equation using the above two equations and a variety of identities will eventually yield the 1D scalar equation for the stream function: ∂ ∂ t ( ∇ 2 ψ ) + ( ∇ × ψ ) ⋅ ∇ ( ∇ 2 ψ ) = ν ∇ 4 ψ {\displaystyle {\frac {\partial }{\partial t}}\left( abla ^{2}\psi \right ...