Download ASTIGMATISM

ASTIGMATISM
WHAT IS ASTIGMATISM?
 An optical defect.
 Vision is blurred.
 Inability to focus.
 Cause
 An irregular curve in the lens.
Types of Astigmatism?
 Regular
 Three types
 With-the-Rule
 Against-the-Rule
 Oblique
 Caused by an
irregularity in the
cornea or
crystalline lens.
 Irregular
 Caused by a
corneal scar or
scattering in the
crystalline lens.
TYPES OF REGULAR ASTIGMATISM
 With-theRule
 This is when
the vertical
meridian is
steepest.
 Againstthe-Rule
 This is when
the
horizontal
meridian is
steepest.
 Oblique
 This is
when the
steepest
curve lies
in
between
120 and
150
degrees
and 30
and 60
degrees.
SIMILAR/CONCURRENT DISORDERS
 Astigmatism can occur with other ocular
disorders.
 Disorders such as Nearsightedness and
Farsightedness.
Nearsightedness (Myopia).
 When the cornea is curved too much or the eye
is longer than it should be.
 This causes the light to be focused in front of
the retina, blurring images at a distance.
Farsightedness (Hyperopia).
 When the cornea is curved too little or the eye
is shorter than it should be.
 This causes light to be focused behind the
retina, blurring images up close.
TREATMENTS
 Corrective Lenses
 Contact Lenses
 Types
 Hard, Soft, Extended wear,
Disposable, Rigid gas permeable,
and Bifocal.
 Eyeglasses
 Can correct most optical defects.
TREATMENTS (continued)
 Surgery
 LASIK-Laser-assisted in-situ keratomileusis
 Makes a hinged cut then reshapes the cornea.
 LASEK-Laser-assisted subepithelial keratomileusis
 A much thinner layer of the cornea is folded.
 PRK-Photorefractive keratectomy
 Removes the outer protective layer of the cornea,
then reshapes it.
Information Compiled from
 http://en.wikipedia.org/wiki/Astigmat
ism_(eye)
 http://www.mayoclinic.com/health/as
tigmatism/DS00230/DSECTION=treat
ments-and-drugs
Presented by Lucas Vigneaux