Perspective on CCT and IOP
Here we offer two nearly parallel systems for approximating
“true” IOP when the Goldmann reading is modified by the corneal
thickness data.
The first system is a micron-to-mm Hg ratio: “As a rough guide,
it can be taken that a 10 micron difference in CCT means approximately
a 0.5mm Hg difference between the measured and the true IOP
with Goldmann tonometry.”1
The second system is the following corneal thickness-to-IOP
correction value approximation:2
Corneal thickness
|
Correction Value
(mm Hg) |
445 |
+7 |
455 |
+6 |
465 |
+6 |
475 |
+5 |
485 |
+4 |
495 |
+4 |
505 |
+3 |
515 |
+2 |
525 |
+1 |
535 |
+1 |
545 |
0 |
555 |
-1 |
565 |
-1 |
575 |
-2 |
585 |
-3 |
595 |
-4 |
605 |
-4 |
615 |
-5 |
625 |
-6 |
635 |
-6 |
645 |
-7 |
1. Shah S. Accurate intraocular pressure measurement-the myth
of modern ophthalmology? Ophthalmology 2000 Oct;107(10):1805-7.
2. Doughty MJ, Zaman ML. Human corneal thickness and its impact
on intraocular pressure measures: a review and meta-analysis
approach. Surv Ophthalmol 2000 Mar-Apr;44(5):367-408.
|
