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Pachymetry of the cornea
Last reviewed: 23.04.2024
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Pachymetry is the measurement of the thickness of the cornea. It is an indirect sign of the integrity of the corneal endothelium. The largest thickness of the cornea is near the limbus (0.7-0.9 mm). Normally, the thickness of the cornea in the center is 0.49-0.56 mm; its increase of more than 0.6 mm may indicate a pathology of the endothelium.
In humans, the average thickness of the cornea varies in a wide range. In men, this figure is 542 μm, in women it is 551 μm. The average value of the daily fluctuation of the corneal thickness in humans is about 6 μm. The measurement data obtained with pachymetry depend on the method of investigation by which the pachymetry was made. These methods are divided into two types: optical and ultrasonic. Optical methods of pachymetry are non-contact. They are used only with a transparent cornea. Ultrasonic methods of pachymetry are divided into contact and immersion methods of measurement.
Despite the variety of equipment and technology, which is designed to measure the thickness of the cornea, the average values can vary in a wide range. Normally, the average thickness of the cornea is 490 - 581μm with the use of an optical pachymeter, and 519 - 536μm - when using the interferometric method. When using the Orbscan system, the normal average corneal thickness will be between 531 and 602 μm.
It should be noted that the average thickness of the cornea should not depend on the principle that is used in such a method of study as pachymetry.
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