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D. M. Win-Hall, A. Glasser; Pascal DCT Measured Accommodative Changes in Intraocular Pressure in Humans. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2806.
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© ARVO (1962-2015); The Authors (2016-present)
To measure dynamic changes in intraocular pressure (IOP) and ocular pulse amplitude (OPA) during accommodation from far-to-near and from near-to-far in human subjects of two different age groups.
Six younger subjects, aged 22-24 years (23±0.89: mean±SD) and six older subjects, aged 40-45 years (43.3±1.75) participated. Accommodative responses were first measured dynamically in the right eye with a Grand-Seiko WAM autorefractor as subjects accommodated for 10 second intervals between a distant target and near targets at 2D and 4D with the left eye occluded. Mean accommodative responses were calculated for the 2D and 4D stimuli. Subsequently, IOP and OPA were measured dynamically in the left eye with a Pascal DCT as subjects accommodated between a distant target and near targets at 2D and 4D viewed through a beam splitter in front of the right eye. The targets were positioned so no vergence change occurred in the DCT measured left eye during accommodation. DCT recordings were from responses both from near-to-far and from far-to-near. From the DCT recordings, mean IOP and OPA was calculated during the 10 second near and far accommodation periods using Matlab code.
For the 2D and 4D stimuli respectively, mean accommodative response amplitudes were 1.64±0.23D and 3.59±0.35D for the young subjects and 0.95±0.56D and 1.25±1.03 D for the older subjects. Mean IOP decreased significantly by 1.56±0.28 mmHg (p<0.05) and 1.99±0.28 mmHg (p<0.05) for the 2D and 4D accommodative stimuli in the young subjects and by 1.20±1.05 mmHg (p<0.05) and 1.75±1.19 mmHg (p<0.05) for the 2D and 4 D accommodative stimuli in the older subjects. Similarly, OPA decreased significantly (p<0.05) for the 2D and 4D accommodative stimuli in both the younger and the older subjects. Accommodative decrease in IOP was significantly linearly correlated with the previously and independently measured accommodative response amplitudes (p<0.05).
Accommodation results in a systematic and significant decrease in IOP and OPA. In some subjects IOP changes observed are abrupt, sustained and unlike transient changes described previously. It is not clear if the IOP changes observed are a cause or a consequence of the accommodative response.
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