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Br J Ophthalmol. Jan 2001; 85(1): 85–87.
PMCID: PMC1723674

Correlation between central corneal thickness, applanation tonometry, and direct intracameral IOP readings

Abstract

BACKGROUND—Several authors reported incorrect high intraocular pressure (IOP) values in eyes with a thick cornea using applanation tonometry. This hypothesis was checked by comparing applanation tonometry with direct intracameral manometry.
METHODS—73 patients, scheduled for intraocular surgery, were enrolled. Immediately before surgery, the following were registered: (i) central corneal thickness (CCT), (ii) applanatory IOP (Perkins/Tonopen), and (iii) intracameral IOP.
RESULTS—The difference between applanatory and intraocular measurements was completely independent of CCT (y=−3.43+3.8x; where y is the difference between applanatory and intracamerally measured IOP (mm Hg) and x is CCT (mm); r2=0.002; p=0.72).
CONCLUSIONS—There is no systematic error of applanation tonometry with increasing CCT. Therefore it is inadequate to recalculate IOP based on regression formula of applanatory IOP versus CCT.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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Figures and Tables

Figure 1
Cannula placed in the anterior chamber.    
Figure 2
Difference between IOPappl and intracameral cannula correlated with CCT. Readings differing by more than 10 mm Hg are marked as circles. y = −3.43+3.8*CCT, r2=0.002; p=0.72, n=73.

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