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Published on: October 3, 2018
Near point of convergence norms measured in elementary school children
Willis C Maples1, Richard Hoenes
1Southern College of Optometry, Memphis, Tennessee 38104, USA. maples@sco.edu
Insights
Near point of convergence (NPC) measures in children with convergence insufficiency (CI) do not significantly change with repeated testing. A NPC break score of 5 cm or less can help differentiate symptomatic from asymptomatic children.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- Convergence insufficiency (CI) is a common binocular vision disorder.
- The near point of convergence (NPC) is a key diagnostic indicator for CI.
Purpose of the Study:
- To evaluate the reliability of NPC measurements in children.
- To establish diagnostic criteria for CI based on NPC findings.
Main Methods:
- NPC was measured six times over 3 years in 539 children.
- Measurements included break and recovery findings using an accommodative target.
- Data were analyzed for changes over time and correlation with symptoms.
Main Results:
- NPC measures showed statistically significant recession over consecutive tests, but not clinically significant.
- One specific NPC break finding significantly predicted symptomatic status.
- NPC break and recovery did not change appreciably with repeated testing within a session.
Conclusions:
- NPC testing is reliable for diagnosing CI in children.
- An NPC break score of 5 cm or less is proposed as a benchmark for differentiating symptomatic from asymptomatic children.
- NPC findings should be considered alongside other benchmarks for CI diagnosis.
Purpose:
Convergence insufficiency (CI) is the most prevalent of binocular dysfunctions. A prime finding in the diagnosis of CI is the near point of convergence (NPC).
Methods:
The NPC was measured six different times on the same 539 children, once in the fall and once in the spring, over the course of 3 years. At each evaluation, the NPC was performed three consecutive times. An accommodative target was used in the testing and the breaks and recoveries were carefully measured and recorded to the nearest centimeter. Normative data for the break and recovery finding were calculated.
Results:
We found that the NPC measures receded significantly over three consecutive tests. The recession was not considered clinically significant for either the break or recovery measures. When various break and recovery findings were compared with reported symptoms, it was discovered that one of the break findings statistically predicted the symptomatic group from the asymptomatic group.
Conclusions:
The NPC break and recovery does not change appreciably with multiple administrations of the test in the same test period. The criteria for a NPC break score to differentiate the more symptomatic and less symptomatic, elementary school children on the average should be 5 cm, or less. The NPC break and recovery criteria described here should be tentatively used as one of the benchmarks in the diagnosis of convergence insufficiency.
