Optical and acoustical measurement of the corneal thickness. A study on phantoms and living human eyes

Abstract

The measurement of corneal thickness serves to answer some clinical questions, such as: the early detection of corneal edema; changes in corneal thickness in glaucoma or keratoconus; operative changes in corneal thickness or curvature for refractive improvement. Early experiments for comparative measurements of the corneal thickness by optical and acoustical methods were carried out in the sixties (Lowe, 1967). In clinical routine optical methods (Jaeger, 1952) usually provide a measurement accuracy of about 0.05 mm, while the precision of ultrasonic standard equipment in general is only 0.1 mm. Nowadays specialized pachymeters are on the market which claim to be precise to +/−9 microns. The aim of this study was to determine the limitations and drawbacks of a high resolution ultrasonic counting technique for clinical practice.