Aniseikonia

• Aniseikonia

  Greek: "unequal images". A binocular condition where the image in one eye is perceived as different in size compared to the image in the other eye.
• Donders


  • Commented upon the probability of unequal image sizes (1864)
• C.Hess


  • Discussed the possibility of aniseikonia (1903)
• Von Rohr


  • Designed iseikonic lenses for aniseikonia
• Iseikonia


  Condition in which the size and shape of the ocular images are equal
• Aniseikonia


  Condition in which ocular images are unequal in size and shape
• Iseikonic lenses


  Lenses which correct aniseikonia and include also the correction of refractive error
• Types of Aniseikonia


  • Static Aniseikonia
  • Dynamic Aniseikonia
• Classifications of Aniseikonia


  • Symmetrical - Overall
  • Symmetrical - Meridional
  • Symmetrical - Axis 90
  • Symmetrical - Axis 180
  • Symmetrical - Axis oblique
  • Symmetrical - Compound
  • Asymmetrical - Pincushion
  • Asymmetrical - Barrel
  • Asymmetrical - Prismatic
  • Asymmetrical - Oblique
• Davis (1959) classification


  • Normal - asymmetric convergence and stereoscopic disparities
  • Abnormal - Asymmetric
  • Abnormal - Symmetric - Overall
  • Abnormal - Symmetric - Meridional
  • Abnormal - Symmetric - Compound
• Testing of Aniseikonia


  • Space Eikonometric Method- based on binocular space perception
  • Direct Comparison Method- based on directly comparing perceived image sizes between the two years
• Space Eikonometer


  • Instrument for measuring aniseikonia
  • Uses a cross with a small white disc at the center of a black square as a target
• Direct Comparison Tests


  • New Aniseikonia Test (Awaya Test)
  • Basic Aniseikonia Test (version 1)
  • Aniseikonia Inspector (version 3)
• New Aniseikonia Test (Awaya Test)


  Manual method to detect and calibrate the Aniseikonic condition
• Basic Aniseikonia Test (version 1)


  Easy-to-use Windows software program to test the aniseikonia of a patient
• Aniseikonia Inspector (version 3)


  Windows software program for the clinical management of aniseikonia. Includes an advanced aniseikonic test and a design tool to calculate correcting prescriptions.
• Symptoms of Aniseikonia


  • Headache
  • Asthenopia (fatigue, burning, tearing, pain, pulling, etc.)
  • Photophobia
  • Reading difficulty
  • Nausea
  • Nervousness
  • Motility (diplopia)
  • Vertigo and Dizziness
  • General fatigue
  • Spatial projection and perception
• Optical Solutions for Aniseikonia


  • Contact Lenses only
  • Glasses only, good VA
  • Glasses only, compromised VA
  • Contact-Glasses Combination
• Partial Occlusion


  Occluding part of the visual field (e.g. placing a dot in the center of one spectacle lens or partially shielding the periphery in one eye)
• Transparent Foil


  Occluding the whole visual field with a partial transparent foil