What effect can a thicker cornea have when measuring IOP by Goldmann tonometry?

Studies have shown a relation between CCT and IOP in eyes with normal and abnormal corneas, when measured by Goldmann applanation tonometry. This has led to the association of increased corneal thickness and falsely elevated tonometer readings.

Why is Goldmann applanation tonometry the gold standard?

Intraocular pressure (IOP) is a critical clinical parameter in the diagnosis and management of glaucoma. Goldmann applanation tonometry (GAT) has been considered as the gold standard for clinical IOP measurement due to its low intra- and inter-observer variability1.

What does Applanation tonometry measure?

This test measures fluid pressure in your eye. The test involves using a slit lamp equipped with forehead and chin supports and a tiny, flat-tipped cone that gently comes into contact with your cornea. The test measures the amount of force needed to temporarily flatten a part of your cornea.

Is having a thick cornea bad?

“In other words, if patients have elevated IOP and thick corneas but normal visual fields and discs, their risk of glaucoma damage is probably low,” he continued. “Their high IOP is probably an artifact of their thick corneas and it’s probably wrong to commit them to a lifetime of unnecessary treatment.”

What is the average corneal thickness?

An average cornea is between 540 µm and 560 µm. A thick cornea is 565 µm or more, with a very thick cornea being greater than 600 µm.

How accurate is TonoPen?

Tonopen more accurately estimated pressure with an average MAE of 5.72 at the central cornea, compared with MAE of 10.83 at the central cornea for iCare (P<0.03).

Is schiotz tonometer accurate?

Our study demonstrated that the Schiotz tonometer may be a useful tool to measure IOP in keratoprosthesis eyes and is more accurate than the Tono-pen, with an absolute median error of 5.4 mm Hg or less compared with true IOP determined by digital manometry. The formulas above may allow for even greater accuracy.

What is the normal intraocular pressure?

Measuring Eye Pressure Normal eye pressure ranges from 12-22 mm Hg, and eye pressure of greater than 22 mm Hg is considered higher than normal. When the IOP is higher than normal but the person does not show signs of glaucoma, this is referred to as ocular hypertension.

Does corneal thickness change with age?

The examination of pachymetric features of the cornea revealed that corneal thickness at the thinnest point of the cornea (Pachy min) decreased significantly with age (p < 0.001) (Table 2). In line with this, corneal volume in the central 10 mm also decreased significantly with age (p < 0.001).