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Objective stray light analysis for cataract grading at the eye

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Project description

One of the most serious eye diseases is the cataract. With over 600.000 surgeries per year it is the most common surgery at the eye in Germany. The diagnostic background is a subjective cataract rating of the doctor respectively the patient. Objective methods for the diagnosis are preferable. They can be conducive to avoid unnecessary and precipitated extraction of clear eye lenses on the basis of fuzzy decision criteria. Surgical risks for the patient and cost for the health insurance can be minimized. Moreover, the assessment of the fraction of lens opacity in the visual loss with a present retinal pathology is of great importance in the diagnosis. The aim of the cooperation project is to develop a method for objectively measuring stray light influences on the visual acuity. The technological base for this project is a Hartmann-Shack wave front aberrometer.

Schematic diagram of the measurement system

Project partners

News

OSAKA- News

A modified Hartmann–Shack aberrometer for measuring stray light in the
anterior segment of the human eye

S. Schramm, B.-U. Seifert, P. Schikowski, J. Prehl, K. S. Kunert, M. Blum, A. Kaeding  und J. Haueisen, Graefe’s Archive for Clinical and Experimental Ophthalmology, Bd. 251, Nr. 8, S. 1967–1977, 2013.

From literature it is known that Hartmann-Shack Wavefront aberrometers, which are commonly used for the measurement of refraction errors of the eye, can also be used for the objective measurement of scattered light. Therefor a reflection at the fundus is created with laser beam which is multiply imaged with a matrix of micro lenses. During imaging, this reflection has to be pass the scattering media of the eye, cornea and lens. This leads to a loss of contrast and a widening of the reflection point.
The applicability of the measurement method is investigated with a study on volunteers. Several stray light parameters were defined within the Hartmann-Shack image and the age dependency was compared to other, established measurement devices like C-Quant and Pentacam. Significant correlations between Michelson Contrast and age and the other measurement devices could be shown. Thus, it is possible to record stray light parameters based on a Hartmann-Shack image.

Schematic optical path of the wavefront aberrometer

Hartmann-Shack image of an eye

Publications & patents

Publications:

  • Schramm, S., Seifert, B.U., Hauueisen, J., Schikowski, P., Prehl, J., Kaeding, A., Kunert, K.S.: Comparative Investigation in Stray Light Measurement in the Human Eye. 46. Jahrestagung der DGBMT, Jena, 16.-19. September 2012

Patents:

  • „Programmable multifunctional aperture for the analysis of optical systems“ (DE 10 2011 102 176 A1) – Offenlegungsschrift; Erfinder: Bernd-Ulrich Seifert, Stefan Schramm, Jens Haueisen