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Elizabeth L. Irving, Carolyn M. Machan; Longitudinal Study Of Age Changes In Vergence Posture. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1785.
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© ARVO (1962-2015); The Authors (2016-present)
In cross-sectional data, we have shown age changes in near vergence posture across the human lifespan (Hrynchak et al AAO 2011). The purpose of the current study was to determine if the same pattern of vergence change is observed longitudinally.
Patient age, distance and near phoria measured by alternate cover test (ACTD and ACTN respectively) and near phoria measure by von Graefe (VGN) were abstracted from 86 files from the School of Optometry clinic, at the University of Waterloo using all available assessment dates. Patient visits occurred between 1968 and 2010 and age of first assessment varied from 6-63years. Files selected were from patients who had been seen for a minimum of 27 years and an average of 16 (SD +/- 5) visits per patient, yielding a total of 1297 ACTD, 1276 ACTN, 696 VGN records. Each of the measures was plotted against age over the available age range for every individual. Linear regression was used to generate age functions and an overall slope and intercept (mean +/- SD) were determined from these. Age function slopes were tested against the following hypotheses: the overall slope was not different from zero; there was no association between intercept and slope or between age of first assessment and slope.
The overall age function slope value for distance vergence posture (0.00 +/- 0.04) was not significantly different from zero. The overall age function slope values for the ACTN and VGN were similar at -0.05 +/- 0.11 and -0.04 +/- 0.29 indicating an overall increase in near exophoria or decrease in near esophoria with age. An association between each patient’s age function intercept and slope r = 0.91 (ACTN) and r = 0.95 (VGN) was found such that in general functions with more positive intercepts had increasingly negative slopes while those with negative intercepts had positive slopes. There was no association between age of first assessment and the slopes of the age functions.
When observed longitudinally, distance vergence posture does not change significantly with age. On the other hand, near vergence posture varied systematically with age similar to cross-sectional data. The lack of association of slope with age of first assessment and the fact that the data could be fit with linear functions indicate that the observed changes are not simply a result of the loss of accommodative convergence.
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