Aberrations are differences from normal vision, which result in the blurring of an image. Long sightedness, short sightedness, presbyopia and astigmatism are considered first order aberrations and are responsible for 85% of the eye’s vision imperfections.
There are also other, higher order aberrations, which can cause poor quality vision. Approximately 80% of these occur on the corneal surface and 20% occur in the lens or in the vitreous body of the eye. Higher order aberrations generally cause difficulties seeing at night, at dusk and at dawn. This is because the rays of light do not meet as a single point, but instead are dispersed into two or more points. When the pupil dilates, your sight becomes significantly worse or you feel easily blinded.