The<unk> , like any other optical system, suffers from a number of specific optical<unk> . The optical quality of the<unk>  is limited by optical<unk> , diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently become possible to measure the<unk>  and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism. The appearance of visual complaints such as halos, glare and monocular diplopia after corneal refractive surgery has long been correlated with the induction of optical<unk> . Several mechanisms may explain the increase in the amount of higher-order<unk>  with conventional eximer laser refractive procedures: a change in corneal shape toward oblateness or prolateness (after myopic and hyperopic ablations respectively), insufficient optical zone size and imperfect centration. These adverse effects are particularly noticeable when the pupil is large.
Aberrations of the eye
Optic neuropathy
Retinal haemorrhage
Vitreoretinopathy
Eye neoplasm
Eye disease
Intraocular hemorrhage
Auditory neuropathy