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A comparison of heterophoria, near point of convergence and vergence ranges at near between presbyopes and non-presbyopes

1 May 1996


This retrospective study compared the heterophorias, near point of convergence, and near vergence ranges between presbyopes and non-presbyopes. A population of 170 subjects were equally divided into two sample groups of 85 each. Significant differences at the (p < 0.05) level between the presbyopic and non-presbyopic populations were found for near phoria. Presbyopes showed increasing exophoria with age at near. Significant differences at near were also found for near point of convergence, base outrecoveries, base in breaks and recoveries. The two categories that did not yield a statistically significant difference were distance phoria and near base out-break. Presbyopes may be at greater risk for near point asthenopia due to this significant decrease in convergence ability.


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