High order aberrations (HOA) refer to complex imperfections of the optical system and are normally present in all eyes in minor unnoticeable amounts. However, as a result of optical refractive surgeries such as Lasik, unnatural and irregular shape of the cornea can result in increases in HOA and thus result in halos double vision, smears, and other visual disturbances. Improvement in lasers over the years has resulted in reducing HOAs but they are still present in some degree.
Measuring and Diagnosing High Order Aberrations
High order aberrations are measured with a wavefront aberrometer. We use the Izon Aberrometer to measure the distortions of light as they pass through the patient's cornea.
Wavefront aberrometry helps in diagnosing both lower order and higher order vision errors based on how the light passing through the eye focuses or refracts.
These are some of the HOAs measured with our Izon Aberrometer.
High Order vs. Low Order Aberrations
Lower order aberrations are common vision errors like nearsightedness(myopia), farsightedness (hyperopia), and astigmatism.
High order aberrations are coma, spherical aberration, and trefoil. These aberrations result in visual disturbances like glare, halos, starbursts, blurring, double vision, etc.