Biomaterial Database

[Significance of the corneal thickness in non-contact tonometry]. 1991

M Gräf

Univ.-Augenklinik Giessen.

In this study the Reichert non-contact tonometer (NCT II) was compared with the Goldmann applanation tonometer (GAT) in 25 subjects (50 eyes; pressure range 9-17 mmHg). The relationship NCT/GAT fulfilled the conditions required for legal verification. Marked differences between the readings of both instruments can be caused by anomalous central corneal thickness, because non-contact tonometry is influenced more than conventional applanation tonometry by the corneal thickness. Starting from a central thickness of 0.51 mm, the NCT is assumed to underestimate the actual intraocular pressure in eyes with thinner and to overestimate it in eyes with thicker cornea by 1 mmHg per 0.01 mm difference of corneal thickness. This value changes with individual corneal tissue qualities and is not valid especially in presence of corneal edema.

UI	MeSH Term	Description	Entries
D007429	Intraocular Pressure	The pressure of the fluids in the eye.	Ocular Tension,Intraocular Pressures,Ocular Tensions,Pressure, Intraocular,Pressures, Intraocular,Tension, Ocular,Tensions, Ocular
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D003315	Cornea	The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)	Corneas
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D014065	Tonometry, Ocular	Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)	Ocular Tonometry
D015715	Corneal Edema	An excessive amount of fluid in the cornea due to damage of the epithelium or endothelium causing decreased visual acuity.	Corneal Edemas,Edema, Corneal,Edemas, Corneal