Related Experiment Video
Updated: Dec 21, 2025
Video-rate Scanning Confocal Microscopy and Microendoscopy
Published on: October 20, 2011
[Pachymetry with a video slit lamp]
Marcus-Matthias Gellrich1, Karsten Hufendiek2
1Augenarztpraxis, Lehmbergstr. 31, 25548, Kellinghusen, Deutschland. FILM.Gellrich@t-online.de.
Background And Objective:
Presentation and application of a method for pachymetry with the slit lamp based on the concept of a defined optical section.
Methods And Patients:
The visible width of an optical section on slit lamp examination with a 45° angle between the slit beam and the central corneal surface was determined in 103 eyes (68 with glaucoma and 35 in patients with keratoconus). The measurements were compared to the pachymetric values previously determined elsewhere for these eyes in order to establish a proportionality factor for calculation of corneal thickness from slit lamp measurements.
Results:
From a linear regression between the external pachymetry and visible width of the optical section in the split lamp, 1.71 was determined to be the factor of proportionality. Applying this factor to single measurements, 82 out of 103 eyes had a maximum difference of 40 µm compared to the external pachymetric values.
Conclusion:
Based on a defined optical section at the slit lamp, clinically relevant estimates can be made for central corneal thickness in diseases, such as glaucoma or keratoconus. The difference to the externally measured pachymetric values was within the range of diurnal changes in corneal thickness for 80% of the eyes. Similar to other pachymetric procedures, the reliability of determination of the corneal thickness with the slit lamp also increases when applied intraindividually or for the same eye in the course of time.
