N Feltgen1, D Leifert, J Funk. 1. Department of Ophthalmology, Albert-Ludwigs- University Freiburg, Germany. feltgen@aug.ukl.uni-freiburg.de
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); r(2) = 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.
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); r(2) = 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.
Authors: P-A Tonnu; T Ho; T Newson; A El Sheikh; K Sharma; E White; C Bunce; D Garway-Heath Journal: Br J Ophthalmol Date: 2005-07 Impact factor: 4.638
Authors: Per Hallberg; Anders Eklund; Kenneth Santala; Timo Koskela; Olof Lindahl; Christina Lindén Journal: Med Biol Eng Comput Date: 2006-07-26 Impact factor: 2.602