Keratoconus

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Keratoconus

• Dr. Abdullah S. Al Yousef

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Definition

• A non-inflammatory eye condition in which the
  normally round dome-shaped cornea progressively
  thins causing a cone-like bulge to develop. This
  results in significant visual impairment.

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Pathophysiology

• All layers of the cornea are believed to be
  affected by KC, most notable features are the.
• ?1. Thinning of the corneal stroma.
• ?2. Ruptures in the Bowman layer.
• ?3. Deposition of iron in the basal epithelial
  cells, forming the Fleischer ring.
• ?4. Breaks in and folds close to the Descemet
  membrane result in acute hydrops and striae,
  respectively

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Symptoms

• Blurred Vision
• Myopia , Astigmatism
• Glare at night
• Photophobia
• Diplopia

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Signs

• Corneal thinning
• Fleischer's ring (an iron colored ring
  surrounding the cone)
• Vogt's striae (stress lines caused by corneal
  thinning)
• Apical scarring (scarring at the apex of the
  cone)
• Munson's sign Its an angulation of the lower
  lid during inferior gaze due to corneal
  protrusion
• Photokeratoscope with    normal round curvature

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• Measurements of corneal thickness and curvature
• The most commonly used approach is ultrasonic
  pachymetry.  the probe must touch the corneal
  surface and topical anesthesia is thus required.
  Its accuracy is dependent on the perpendicularity
  of the probe's application to the cornea and
  reproducibility relies on precise probe placement
  on the corneal center.
• The Orbscan II corneal topography system (Bausch
  Lomb) is an optical scanning-slit instrument
  that provides topographic analysis and
  pachymetric measurements of the cornea.
• This disparity between instruments can result
  from their distinct methodologies. The noncontact
  Orbscan system measures the hydrated mucous
  component of the tear film over the cornea
  contact ultrasonic pachymetry does not. Thus,
  Orbscan readings are higher than ultrasonic
  readings.

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Treatment

• To improve vision to stop progression
• Glasses or soft contact lenses in mild or early
  keratoconus.
• Rigid gas permeable lenses in the intermediate
  stages.
• Advancing keratoconus cant tolerate rigid contact
  lens
• New treatments
• Corneal ring -Intacts corneal rings (placing with
  the corneal stroma in the periphery of the
  cornea. The result is a flatter cornea and
  clearer vision.)
• C3R - Corneal Collagen Crosslinking with
  Riboflavin. Increasing collagen crosslinking
  within the cornea. Combined with Intacs to
  provide a combined effect and provide greater
  stability than one treatment alone.
• Cornea transplant penetrating keratoplasty. A
  donor cornea will replace the thinning cornea and
  can often provide stable vision. Patient will
  most likely need glasses or contact lenses for
  clear vision

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• Thank you