convergence

convergence

• 1.
  Measurement of Convergence
• 2.
  Measurement of ConvergenceIt is essential that assessment of vergence is made during an eye examination There are many aspects to the vergence response
• 3.
  Near Point ofConvergence (NPC)
• 4.
  NPC Subjective NPC:Patient reports diplopia Objective NPC: Clinician observes point when one eye turns out
• 5.
  NPC Less than12cm is normal Between 12 and 15cm is suspect Greater than 15cm is anomalous: orthoptic training is indicated
• 6.
  Jump Vergence Amore natural test Patient changes fixation from distance to near If task is difficult patient will attempt to look away
• 7.
  Fusional Vergence Phoriasare kept latent by the fusion reflex Large phorias may need a large fusional effort to maintain binocularity Important to know how much fusional vergence is being used
• 8.
  Positive Fusional Reserves
• 9.
  Negative Fusional Reserves
• 10.
  Measurements Break PointRecovery Point Blur Point
• 11.
  Base In
• 12.
  Base Out
• 13.
  Relative Vergence Wheneyes converge accommodation is stimulated The target will become blurred The amount of ∆ to the blur point is known as the relative convergence
• 14.
  Relative Vergence NegativeRelative Convergence: amount of BI ∆ to blur Positive Relative Convergence: amount of BO ∆ to blur
• 15.
  Vertical Fusional ReservesMeasured with Base up or down ∆ Fusional range small
• 16.
  Normal Values
• 17.
  Clinical Value Distancephoria: 8XOP Positive reserve: 16 ∆ Total +ve vergence: 8 + 16 =24 1/3 of total being used to over come phoria
• 18.
  Accommodation and Vergence
• 19.
  Relative Accommodation Amountof accommodation which can be exerted while vergence remains constant Measured by using +ve and -ve lenses
• 20.
  Zone of ClearVision
• 21.
  Zone of ClearVision
• 22.
  Zone of ClearVision
• 23.
  Summary Consider allaspects of vergence NPC a routine measure Phoria a routine measure Fusional reserves should be considered in diagnosis and management of BV problems