Doctoral Dissertations

Wavelet analysis of electroretinograms and its clinical application


"The electroretinogram (ERG) is a powerful clinical technique used in clinics around the world to diagnose and monitor the health of the retina. The ERG is the record of the electrical activity of the retina in response to light. Under scotopic conditions (for low light levels, approximately less than 10 scotopic trolands), the human ERG in response to a flash of white light has a specific form: an initial negative deflection called the a-wave, followed by a positive deflection called the b-wave which then falls back to zero. Superimposed on the b-waves are a few high frequency oscillatory potentials. Daubechies D4 wavelets were used to do an eight scale multiresolution analysis of these waves. The most important wavelet coefficients that contribute to the various components of the ERG were identified using the following procedure: (i) Contribution of each wavelet coefficient to the L¹-norm of the wave is determined; (ii) Only coefficients which contribute at least 2.5% of the maximum contribution are retained; (iii) From this reduced set only those coefficients that contribute to signals within 2 standard deviation from the norm are retained as the best basis; (iv) ERG signals were reconstructed using these best basis; (v) The coefficients that contribute to different components of the ERG were directly read from scalograms of these reconstructed waves. Best basis were obtained for normal ERGs as well as ERGs obtained from patients with Rod-cone dystrophy and Duchenne muscular dystrophy. The differences in the basis sets are used to hypothesize the differences in the physiological mechanisms involved in the production of these pathological ERGs"--Abstract, page iii.


Lakshminarayanan, V.
Story, J. Greg

Committee Member(s)

Peacher, Jerry
Flores, Ricardo
Watkins, Steve Eugene, 1960-



Degree Name

Ph. D. in Physics


University of Missouri--St. Louis. Department of Physics
University of Missouri--St. Louis. School of Optometry
University of Missouri--St. Louis Research Board


Dissertation completed as part of a cooperative degree program with the University of Missouri--Rolla and the University of Missouri--St. Louis.


University of Missouri--Rolla

Publication Date

Spring 2002


xii, 120 pages

Note about bibliography

Includes bibliographical references (pages 116-119).


© 2002 Srinivasa Varadharajan, All rights reserved.

Document Type

Dissertation - Citation

File Type




Subject Headings

Wavelets (Mathematics)

Thesis Number

T 8076

Print OCLC #


Link to Catalog Record

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