Abstract
Purpose :
Correct assessment of intraocular pressure (IOP), horizontal corneal diameter (HCD), central corneal thickness (CCT) and axial length (AL) are critical for accurate diagnosis and follow-up of children with PCG. In PCG, the value of IOP may be influenced by CCT, corneal edema, Descemet's membrane ruptures and corneal opacities as well as by the type of tonometer used for its measurement. Thus, this study aims to compare the measurements of IOP obtained with the hand-held Draeger applanation tonometer (DAT) and the Tono-pen Avia® (TPAvia®) in PCG correlating them with changes found in the cornea and AL.
Methods :
Children with PCG without surgery or PCG already operated were submitted, under inhalation anesthesia (sevofluorane), to the measurements of IOP, HCD, CCT and AL by the same examiner (SC). IOP was measured with DAT and then with TPAvia® in the center of the cornea, regardless of the presence or absence of corneal edema, Descemet's membrane ruptures and corneal opacities; the HCD was measured with the Jameson compass and the CCT and AL with the DGH5100e echobiometer. The cornea was biomicroscopically evaluated for the presence or absence of edema, Descemet's membrane ruptures and central opacities. We investigated the correlation among the IOP values obtained with both tonometers and the measurements of HCD, CCT, AL and the biomicroscopic findings of the cornea. In the statistical analysis, mixed linear models were constructed that adjust for non-independence of right and left eyes.
Results :
We included 52 eyes of 32 patients. The mean CCT (SD) was 620 (93.1) μm and the mean IOP with DAT was 14.4 (7.04) mmHg while it was 25.4 (9.93) mmHg with TPAvia®. The average AL was 24.80 (3.70) mm. CCT and AL were significant predictors of IOP measured with TPAvia® (P = 0.014 and P = 0.030, respectively). Age, diffuse bullous keratopathy, and central corneal leukoma were not significant predictors. Taking DAT as a reference, CCT was a predictor of IOP with TPAvia®, that is, for every 10 μm increase in CCT, a 0.5 mmHg increase in IOP measured with TPAvia® and for each 1mm increase in AL is expected. An increase of 1.1 mmHg is expected with TPAvia® if the other factors are fixed.
Conclusions :
Central corneal thickness and AL are associated with the differences between IOP measurements done with DAT and TPAvia®, however TPAvia® tonometer presents higher IOP values.
This is a 2020 ARVO Annual Meeting abstract.