Are We There Yet? Celebrating the Centennial of the Schiøtz Tonometer

Intraocular pressure assessment after laser in situ keratomileusis: a review

This paper aims to review the current methods available for the measurement of intraocular pressure after myopic laser in situ keratomileusis for the correction of myopia. Searches were performed for studies that assessed or compared various methods of intraocular pressure assessment. There were 20 eligible studies that explored the use of pneumotonometry, pressure phosphene tonometry, rebound tonometry, dynamic contour tonometry, statistical modeling, mathematical formulae, ocular response analyzer and even measuring intraocular pressure on the nasal cornea. Our review shows that an ideal method would be one that is independent of corneal factors. Dynamic contour tonometry and pressure phosphene tonometry held promise in research settings. More studies need to be done to validate the new methods of intraocular pressure assessment, especially in glaucoma patients. It is important to empower laser in situ keratomileusis patients with knowledge of these difficulties and potential implications for the future.

Poor agreement between Goldmann and Pascal tonometry in eyes with extreme pachymetry

AIM

To compare the intraocular pressure (IOP) measurements obtained using the Pascal dynamic contour tonometer (PDCT) with the standard Goldmann applanation tonometry (GAT) and to correlate them with the central corneal thickness (CCT) in a non-glaucomatous population.

METHODS

We prospectively measured IOP using PDCT and GAT in random order in 100 normal eyes. CCT was analysed with an ultrasonic pachymeter in each case. Statistical analysis of baseline and stratified data included intraclass correlation coefficient (ICC), Lin correlation, and Bland-Altman analysis to evaluate the agreement between both techniques.ResultsGAT was used first in 51 eyes and PDCT in 48 cases. Mean IOP was 14.8 mm Hg with GAT and 20.3 mm Hg with PDCT. Mean pachymetry was 553.23 micrometres (microm) (SD: 4.7 microm). Global agreement of IOP between GAT and PDCT was 0.09 by ICC and 0.170 by Lin correlation. When CCT values ranged between 540 and 545 microm, the agreement between both tonometers was optimal (ICC 0.54 and Lin 0.61). Outside these pachymetry values, agreement between both tonometers diminished dramatically.

CONCLUSION

Statistically significant agreement between both devices was reached only at intermediate pachymetry readings in contrast with other studies that show excellent global agreement between GAT and PDCT.