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E. Milla, S. Duch, M. Sacoto, C. Masuet; Correlation Between Pascal and Goldmann Tonometry in Eyes With Different Pachymetry Values . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4446.
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© ARVO (1962-2015); The Authors (2016-present)
the widely accepted international gold standard for the measurement of intraocular pressure (IOP) is Goldmann applanation tonometry (GAT); however the accuracy of this method has been questioned in eyes with abnormal corneas and after LASIK. The aim of our study is to compare the IOP measurements obtained using the Pascal dynamic contour tonometer (PDCT) with the standard GAT and to correlate them with central corneal thickness (CCT) in a non–glaucomatous population.
we prospectively measured IOP using PDCT and GAT in 99 eyes. GAT and PDCT were randomly performed on a slit lamp with a calibrated tonometer and the mean of three consecutive GAT readings was calculated. CCT was analyzed with an ultrasonic pachymeter in each case at the end of the procedure. Statistical analysis included Pearson coefficient correlation and Spearman test for non parametric values.
GAT was used first in 51 eyes and PDCT in 48. Mean IOP was 14,89 mm Hg ± 3,35 SD with GAT and 20,33 mmHg ± 4,73 SD with PDCT. Mean pachymetry (CCT) was 553,23 microns (SD: 36,46 µ). Pearson correlation (r2) values between both tonometers were the following: r2=0,187 when CCT was < 513 µ; r2=0,358 when CCT was between 513–523 µ; r2=0,183 when CCT: 524–539 µ; r2=0,936 when CCT: 540–545 µ ( r2=0,990 when CCT= 545 µ; p = 0,01); r2=0.70 when CCT: 546–554 µ; r2=0,287 when CCT: 555–561µ; r2=0,345 when CCT: 562–569 µ; r2=0,598 when CCT: 570–574 µ; r2=0,584 when CCT: 575–594 (p = 0,046) and r2=0,450 when CCT >595 µ.
IOP readings obtained by PDCT were 5,5 mm Hg higher on average than the readings obtained by GAT. This difference became even larger in cases in which IOP was measured by GAT with a prior PDCT reading. Statistically significant correlation between both devices were only reached when pachimetry was around "normal" (545µ) values. Thus, in our study there was a lack of correlation between GAT and PDCT either in thinner or thicker corneas. Our results differ from several published studies in which IOP measurements taken with PDCT showed an excellent concordance with the ones obtained by GAT. Further studies are requiered to support the potential clinical role for the PDCT particularly for subjects with pachymetries outside of the normal range.
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