Search results
Results From The WOW.Com Content Network
Irregular astigmatism – principal meridians are not perpendicular. In with-the-rule astigmatism, the eye has too much "plus" cylinder in the horizontal axis relative to the vertical axis (i.e., the eye is too "steep" along the vertical meridian relative to the horizontal meridian).
Keratoconus. Keratoconus ( KC) is a disorder of the eye that results in progressive thinning of the cornea. [ 3] This may result in blurry vision, double vision, nearsightedness, irregular astigmatism, [ 4] and light sensitivity leading to poor quality-of-life. [ 3][ 5] Usually both eyes are affected. [ 3] In more severe cases a scarring or a ...
Aberrations of the eye. The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. [1] Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods ...
Other symptoms may include double vision, headaches, and eye strain. [1] Near-sightedness is due to the length of the eyeball being too long, far-sightedness the eyeball too short, astigmatism, the cornea being the wrong shape, and presbyopia aging of the lens of the eye such that it cannot change shape sufficiently. [1]
Pellucid marginal degeneration ( PMD) is a degenerative corneal condition, often confused with keratoconus. It typically presents with painless vision loss affecting both eyes. Rarely, it may cause acute vision loss with severe pain due to perforation of the cornea. It is typically characterized by a clear, bilateral thinning ( ectasia) in the ...
Astigmatism (optical systems) An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek α- ( a ...
Treatment options include contact lenses and intrastromal corneal ring segments for correcting refractive errors caused by irregular corneal surface, [7] [8] corneal collagen cross-linking to strengthen a weak and ectatic cornea, [9] or corneal transplant for advanced cases.
LASIK or Lasik (laser-assisted in situ keratomileusis), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and astigmatism. [1]