Comparison of Four Different Aberrometers for Evaluation of Higher Order Visual Aberrations

Inclusion Criteria: * male or female, at least 18 years of age * no ocular abnormality other than refractive error * patient in generally good \& stable overall health * has not worn contact lenses (hard or gas permeable lenses for at least 3 weeks and soft lenses for at least 3 days) prior to the study exam * corneal topography must be normal, as judged by the investigator * topical anesthesia and mydriatics must be tolerated * patient must be able to fixate steadily * ability to understand and provide informed consent to participate in this study Exclusion Criteria: * history of ocular surgery * history of ocular trauma, infection, disease, or abnormality other than refractive error * myopia or hyperopia \> 7.0 D, astigmatism \>3.0 D * uncorrectable visual acuity below 20/20 * abnormal corneal topography pattern including, but not limited to keratoconus, forme fruste keratoconus, or corneal warpage * pupil sizes below 6.0 mm under mydriasis * iris problems including, but not limited to, coloboma and previous iris surgery * ocular media problems, corneal, lens and/or vitreous opacities including, but not limited to cataract * ocular movement abnormalities including, but not limited to, strabismus or nystagmus * phenol red thread test (Zone Quick-Menicon Ltd) less than 9 mm/15 seconds * pregnancy and lactation