Higher-order aberrations or HOAs are more complex vision errors than lower-order aberrations, which have more familiar names such as nearsightedness (myopia), farsightedness (hyperopia) and astigmatism. HOAs have relatively unfamiliar names such as coma, spherical aberration and trefoil. These types of aberrations can produce vision errors such as difficulty seeing at night, glare, halos, blurring, starburst patterns or double vision. No eye is optically perfect, which means that all eyes have at least some degree of higher-order aberrations, even when no lower order aberrations are present. If you are diagnosed with higher-order aberrations, you need not be concerned unless they are significant enough to cause vision symptoms. HOAs make up only about 15% of the optical aberrations in the average eye but can have a pronounced effect on vision quality. Dr. Crawford measures these higher order aberrations during the comprehensive eye exam and can determine how they may affect you during different tasks. Sometimes it is necessary to have more than one glasses or contact lens prescription to handle the changes caused by HOAs. There is currently a lot of research being done to produce glasses and contact lenses that can correct these HOAs.