Performance of Confocal Scanning Laser Tomograph Topographic Change Analysis (TCA) for Assessing Glaucomatous Progression

¹ Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
² Optometry and Visual Science, City University, London, United Kingdom

^* To whom correspondence should be addressed. E-mail: cbowd{at}eyecenter.ucsd.edu.

	Abstract

Purpose: To determine the sensitivity and specificity of confocal scanning laser ophthalmoscope Topographic Change Analysis (TCA, using Heidelberg Retina Tomograph, HRT) parameters for discriminating between progressing glaucomatous and stable healthy eyes. Methods: 0.90, 0.95 and 0.99 specificity cut-offs for various (n=70) TCA parameters were developed using 1000 permuted topographic series derived from Heidelberg Retina Tomograph (HRT) images of 18 healthy eyes from Moorfields Eye Hospital, imaged at least four times. Cut-offs were then applied to topographic series from 36 eyes with known glaucomatous progression (by optic disc stereo-photograph assessment and/or standard automated perimetry Guided Progression Analysis, GPA) and 21 healthy eyes from the UCSD Diagnostic Innovations in Glaucoma Study (DIGS), all imaged at least four times, to determine TCA sensitivity and specificity. Cut-offs also were applied to 210 DIGS patient eyes imaged at least 4 times with no evidence of progression (non-progressors) by stereo-photography or GPA. Results: The TCA parameter providing the best sensitivity/specificity trade-off using the 0.90, 0.95 and 0.99 cut-offs was the largest clustered superpixel area within the optic disc margin (CAREA^disc mm²). Sensitivities/specificities for classifying progressing (by stereo-photography and/or GPA) and healthy eyes were 0.778/0.809, 0.639/0.857 and 0.611/1.00, respectively. In non-progressor eyes, specificities were 0.464, 0.570 and 0.647 (i.e., lower than in the healthy eyes). Additionally, TCA parameter measurements from non-progressing eyes were similar to those from progressing eyes. Conclusions: TCA parameters can discriminate between progressing and longitudinally followed healthy eyes. Low specificity in apparently non-progressing patient eyes suggests early progression detection using TCA.

Key Words: glaucoma posterior segment, optic disc, scanning laser ophthalmoscopy, progression

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