Most corneal topographers are slope-based instruments, measuring corneal slope based on light reflected by the cornea acting as a mirror. This mirror method limits corneal coverage to about 9 mm diameter. Both refractive surgery and contact lens fitting actually require a larger coverage than is obtainable using slope-based instruments. Height-based instruments should be able to measure a cornea/sclera area that is twice the size (four times the area) of slope-based topographers with an accuracy of a few microns. We have been testing a prototype of a new model height-based topographer manufactured by Euclid Systems. We find that single shots can produce a corneal coverage of up to 16 mm vertical and 20 mm horizontal. The heights and slopes in the corneal region have good replicability. Although the scleral region is noisier, it is the only topographer available able to measure scleral topography that is critically important to contact lens fitting. There are a number of improvements to the Euclid software and hardware that would enable it to fill an important niche in eye care and eye research.

Date Published: 13 June 2002
PDF: 10 pages
Proc. SPIE 4611, Ophthalmic Technologies XII, (13 June 2002); doi: 10.1117/12.470589

Published in SPIE Proceedings Vol. 4611:
Ophthalmic Technologies XII
Fabrice Manns; Per G. Soederberg; Arthur Ho, Editor(s)