A spherical aberration is when your eyes see spheres around lights bouncing off reflective or magnifying surfaces, resulting in an imperfection of the produced image.
The accommodative response of the eye results in changes to the lens shape and substantially affects the Wavefront aberration pattern. Most eyes show positive spherical aberration when unaccomodated with a trend toward negative spherical aberration on accommodation. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of method's to measure and correct ocular astigmatism. The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of method's to measure and correct ocular astigmatism. spherical aberration. n. The blurring of an image that occurs when light from the margin of a lens or mirror with a spherical surface comes to a shorter focus than light from the central portion. spherical aberration. spherical aberration. Parallel light rays passing through a lens with a spherical surface focus at different points depending on whether they pass through the lens closer to the edge or closer to the center. Spherical Aberration is an optical problem that occurs when all incoming light rays end up focusing at different points after passing through a spherical surface. Spherical Aberration is not just caused by lens design, but also by the quality of the lens material. Lenses made of poor quality material and large bubbles can drastically impact light refraction. A perfect lens would have all light rays converge in a single focal point, as illustrated below: The spherical aberration of the cornea is usually positive whereas the young crystalline lens exhibits a negative spherical aberration. Besides, there is strong evidence of compensation for aberrations between the cornea and intraocular optics in cases of astigmatism (horizontal/vertical) and horizontal coma. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of method's to measure and correct ocular astigmatism. Spherical aberration is an optical effect observed in an optical device (lens, mirror, etc.) that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike nearer the centre. Spherical aberration of collimated light incident on a concave spherical mirror. A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. It signifies a deviation of the device from the norm, i.e., it results in an imperfection of the produced image. On top is a depiction of a perfect lens without spherical aberration: all incoming rays are focused in the focal point. The bottom example depicts a real lens with spherical surfaces, which produces spherical aberration: The different rays do not meet after the lens in one focal point. The further the rays are from the optical axis, the closer to the lens they intersect the optical axis (positive spherical aberration). Spherical aberration of collimated light incident on a concave spherical mirror. A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. Spherical Aberration. The most serious of the classical Seidel monochromatic lens aberrations that occurs with microscope objectives, spherical aberration, causes the specimen image to appear hazy or blurred and slightly out of focus.  connect with local specialist for a. FREE CONSULTATION in your area. CALL. Spherical aberration is a visual effect that occurs when increased refraction of light rays strike a lens or a mirror. In laymans' terms, a spherical aberration is when your eyes see spheres around lights bouncing off reflective or magnifying surfaces, resulting in an imperfection of the produced image. Spherical aberrations can occur from changes in the eye's anatomy or physiology.  Higher-order aberrations have relatively unfamiliar names such as coma, spherical aberration and trefoil. These types of aberrations can produce vision errors such as difficulty seeing at night, glare, halos, blurring, starburst patterns or double vision (diplopia). 
https://en.wikipedia.org/wiki/Aberrations_of_the_eye https://en.wikipedia.org/wiki/Aberrations_of_the_eye http://www.thefreedictionary.com/spherical+aberration https://photographylife.com/what-is-spherical-aberration https://en.wikipedia.org/wiki/Aberrations_of_the_eye https://en.wikipedia.org/wiki/Spherical_aberration https://en.wikipedia.org/wiki/Spherical_aberration http://micro.magnet.fsu.edu/primer/java/aberrations/spherical/index.html http://www.lasikeyesurgery.com/what-is-spherical-aberration.html http://www.allaboutvision.com/conditions/aberrations.htm
what is spherical aberration in eye