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Convergence

  • Both eyes adduct independent with each other
  • Accompanies accommodation (AC/A ratio)
  • Used to maintain fixation on near targets
  • Quantified by measuring convergence amplitudes and near point of convergence
  • Dysfunctional convergence is seen in Exophoria and Exotropia
    • When accompanies exophoria, sensory fusion may be able to be strengthened by convergence exercises
    • see convergence insufficiency

Convergence Amplitudes

  • Testing requires sensory fusion
  • With a fixation target at near and distance, look through progressively larger base out prisms until diplopia occurs.
    • The break point is the prism value where diplopia occurs
    • The recovery point is the prism value where sensory fusion is re-established
  • Normal measurements for break point:
    • Near: 30Δ to 40Δ
    • Distance: 20Δ to 30Δ

Near Point of Convergence

  • Distance from nose where diplopia occurs
  • Normal near point:
    • 4cm to 10cm