ASTIGMATISM

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ASTIGMATISM
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WHAT IS ASTIGMATISM?

• An optical defect.
• Vision is blurred.
• Inability to focus.
• Cause
• An irregular curve in the lens.

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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.

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TYPES OF REGULAR ASTIGMATISM

• With-the-Rule
• This is when the vertical meridian is steepest.

• Oblique
• This is when the steepest curve lies in between
  120 and 150 degrees and 30 and 60 degrees.

• Against-the-Rule
• This is when the horizontal meridian is steepest.

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SIMILAR/CONCURRENT DISORDERS

• Astigmatism can occur with other ocular
  disorders.
• Disorders such as Nearsightedness and
  Farsightedness.

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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.

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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.

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TREATMENTS

• Corrective Lenses
• Contact Lenses
• Types
• Hard, Soft, Extended wear,
• Disposable, Rigid gas permeable,
• and Bifocal.
• Eyeglasses
• Can correct most optical defects.

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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.

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Information Compiled from

• http//en.wikipedia.org/wiki/Astigmatism_(eye)
• http//www.mayoclinic.com/health/astigmatism/DS002
  30/DSECTIONtreatments-and-drugs

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Presented by Lucas Vigneaux