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Application of Shape-based Analysis Methods to OCT Retinal Nerve Fiber Layer Data in Glaucoma

Gunvant, Pinakin BS Optom, PhD, FAAO* †; Zheng, Yufeng PhD; Essock, Edward A. PhD† §; Parikh, Rajul S. MS; Prabakaran, Selvaraj BS Optom; Babu, Jonnadula Ganesh BS Optom; Shekar, Garudadri Chandra MD; Thomas, Ravi MD

doi: 10.1097/IJG.0b013e318050ab65
Original Studies

Purpose (1) To evaluate the performance of shape-based analysis [wavelet-Fourier analysis (WFA) and fast Fourier analysis (FFA)] applied to retinal nerve fiber layer (RNFL) thickness values obtained from the optical coherence tomograph (OCT) to discriminate healthy and glaucomatous eyes. (2) To compare the performance of the shape-based metrics to that of the standard OCT output measures (Inferior Average and Average Thickness).

Methods RNFL values were obtained from 152 eyes of 152 individuals (83 healthy and 69 “mild”-stage perimetric glaucoma). WFA and FFA were performed on the RNFL values and linear discriminant functions for both were obtained using Fisher linear discriminant analysis. Performance was evaluated by calculating sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (ROC area).

Results The ROC area of the shape-based methods [0.94 (WFA) and 0.88 (FFA)] was greater than that of OCT metrics [0.81 (Inferior Average) and 0.74 (Average Thickness)]. Specifically, WFAs performance was significantly better than both the FFA (P=0.009) and the Inferior Average (P=0.001). Inferior average performed significantly better than Average Thickness (P=0.006).

Conclusions The ability to differentiate glaucomatous from healthy eyes using stratus OCT measurements is improved by using these analysis methods that emphasize the shape of the RNFL thickness pattern.

*Southern College of Optometry, Memphis, TN

Department of Psychological and Brain Sciences

§Department of Ophthalmology and Vision Science, University of Louisville, Louisville, KY

Alcorn State University Mississippi

L.V. Prasad Eye Institute, Hyderabad, India

Supported in part by grants from Kentucky Science and Engineering Foundation (KSEF).

Commercial interest: Edward A. Essock: Patent RNFL shape analysis Patent No. 7,139,602.

Pinakin Gunvant: Research support from Heidelberg Engineering and Carl Zeiss Meditec.

Reprints: Dr Pinakin Gunvant, BS Optom, PhD, FAAO, Southern College of Optometry, 1245 Madison Avenue, Memphis TN 38104-2222 (e-mail:

Received for publication August 11, 2006; accepted February 22, 2007

© 2007 Lippincott Williams & Wilkins, Inc.