Abstract
Purpose: :
To test and to measure the real size of human fundus objects with the Retina-Stripe-Projector (RSP, Carl Zeiss Meditec, Jena, Germany).
Methods: :
Fundus images were taken from 52 eyes with the RSP (based on an interferometer of Baumbach). Distances between stripes were calculated according to the method of Littmann (influenced by the curvature of the cornea and ammetropia) and measured with the RSP.
Results: :
Calculated object size with Littmann method showed a ±5.47% (0.01 - 13.63%) difference in comparison to measured object size with RSP. In 51 of 52 eyes measured object size was smaller than calculated size by the Littmann method. In cases with non-axial ammetropia differences between both methods were more considerable compared to eyes with ammetropia caused by axial length. By using the corrected Littmann formula respecting the axial length, the difference between calculated and measured object size may be reduced to nearly 1%.
Conclusions: :
Fundus object size calculation by the Littmann method should be corrected in cases of non axial length ammetropia. A considerable improvement of the measured object size compared to the calculated object size may be reached by using the axial length as a further correction factor.
Clinical Trial: :
University of Jena, 1959-02/07
Keywords: imaging/image analysis: clinical • optical properties • retina