Ghost images and ghosting, even with one eye closed
Light rings and glare around light sources, especially at night
Reduced contrast in low light conditions despite good daytime acuity
Distorted or coloured edges on images and text
Optical aberrations can be detected in every eye. Lower-order aberrations (LOAs) such as myopia, hyperopia and astigmatism account for over 80% of all refractive errors and are easily corrected with glasses or standard contact lenses.
Higher-order aberrations (HOAs) are more complex optical errors — such as coma, trefoil and spherical aberrations — that cannot be corrected with glasses. In keratoconus, HOAs occur up to 6× more frequently.
Light rays through the corneal periphery are refracted differently than through the centre. Causes comet-tail distortions, very disturbing when driving.
Light rays at the lens edge refract differently than centrally. Causes halos and blurry edges around light sources.
Three symmetrical lobes of distortion around a light source ('cloverleaf' shape). Usually less severe than coma.
Cone-shaped cornea with severe distortion
Complications after laser eye surgery
After infection, trauma or transplant
Sicca syndrome, Sjögren's
Clouding of the eye lens