• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of brjopthalBritish Journal of OphthalmologyVisit this articleSubmit a manuscriptReceive email alertsContact usBMJ
Br J Ophthalmol. Jan 2001; 85(1): 85–87.
PMCID: PMC1723674

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


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.

Full Text

The Full Text of this article is available as a PDF (115K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • GOLDMANN H, SCHMIDT T. Uber Applanationstonometrie. Ophthalmologica. 1957 Oct;134(4):221–242. [PubMed]
  • GOLDMANN H, SCHMIDT T. [Further contribution to applanation tonometry]. Ophthalmologica. 1961 Jun;141:441–456. [PubMed]
  • Hansen FK, Ehlers N. Elevated tonometer readings caused by a thick cornea. Acta Ophthalmol (Copenh) 1971;49(5):775–778. [PubMed]
  • Herndon LW, Choudhri SA, Cox T, Damji KF, Shields MB, Allingham RR. Central corneal thickness in normal, glaucomatous, and ocular hypertensive eyes. Arch Ophthalmol. 1997 Sep;115(9):1137–1141. [PubMed]
  • Ehlers N, Bramsen T, Sperling S. Applanation tonometry and central corneal thickness. Acta Ophthalmol (Copenh) 1975 Mar;53(1):34–43. [PubMed]
  • Whitacre MM, Stein RA, Hassanein K. The effect of corneal thickness on applanation tonometry. Am J Ophthalmol. 1993 May 15;115(5):592–596. [PubMed]
  • Argus WA. Ocular hypertension and central corneal thickness. Ophthalmology. 1995 Dec;102(12):1810–1812. [PubMed]
  • Johnson M, Kass MA, Moses RA, Grodzki WJ. Increased corneal thickness simulating elevated intraocular pressure. Arch Ophthalmol. 1978 Apr;96(4):664–665. [PubMed]
  • Copt RP, Thomas R, Mermoud A. Corneal thickness in ocular hypertension, primary open-angle glaucoma, and normal tension glaucoma. Arch Ophthalmol. 1999 Jan;117(1):14–16. [PubMed]
  • Stodtmeister R. Applanation tonometry and correction according to corneal thickness. Acta Ophthalmol Scand. 1998 Jun;76(3):319–324. [PubMed]
  • Marx W, Madjlessi F, Reinhard T, Althaus C, Sundmacher R. Mehr als vier Jahre Erfahrung mit der elektronischen intraokularen Nadel-Druckmessung bei irregulären Hornhäuten. Ophthalmologe. 1999 Aug;96(8):498–502. [PubMed]
  • Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986 Feb 8;1(8476):307–310. [PubMed]

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.

Articles from The British Journal of Ophthalmology are provided here courtesy of BMJ Group


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...