الفهرس 
Ocular aberrations and wavefront analysisOnly 14 pages are availabe for public view
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Abstract
Refractive surgical procedures attempt to improve unaided visual
acuity and correct spherocylindrical errors by reshaping the central
cornea which is the most powerful refractive element of the eye and the
easiest to access surgically.
Refractive surgery induces an increase in higher-order aberrations
(HOAs) and may lead to visual losses that are detected under scotopic
(low light) conditions and by low-contrast visual acuity testing. The
increases in HOAs are known to be responsible for patients complaints
of glare, halo and disturbances in night vision.
Higher-order aberrations due to a large difference between the
treated and the non – treated cornea, or a large pupil diameter in relation
to treatment zone diameter can be reduced by enlargement of the optical
zone reducing halos and glare.
The FOZ was an important parameter in determining visual
quality. It is important to differentiate between FOZ and the ablation
zone. In order to minimize aberrations, the FOZ should be comparable or
larger than the entrance pupil as light passing outside the FOZ tends to
cause aberrations reducing the two point discriminability of the retina.
Therefore, the evaluation of the functional optical zone (FOZ) can
help us in understanding the changes that occurred postoperatively as
changes in corneal shape, and night vision disturbances.
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In order to improve the results and patient satisfaction, it is
important to consider the postoperative FOZ and preoperative pupil
diameter also we should reconsider the amount of attempted correction.
Patients undergoing LASIK procedures display an increase of night
vision disturbances even when the results of the surgery are considered
entirely satisfactory. Secondary astigmatism and other higher order
aberrations are significantly correlated with night vision disturbances so
the attempted correction should be always noticed. Further studies will be
important to declare the degree of secondary astigmatism induced by toric
ablations.