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PJ Harasymowycz, AS Hafez, MR Lesk; The validation of importing the disc area contour line in Heidelberg Retina Tomography: Do disc area measurements change following IOP reduction? . Invest. Ophthalmol. Vis. Sci. 2002;43(13):257.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To measure optic disc area (DA) changes using Heidelberg Retina Tomography (HRT) after intra-ocular pressure (IOP) reduction in glaucoma. Methods:A prospective study of glaucoma and ocular hypertensive patients undergoing an IOP reduction of at least twenty percent. Patients had HRT before and after IOP reduction. Three masked observers of varying experience drew the contour line of the optic discs on both pre- and post-IOP reduction mean topography images. Each observer redrew the contour line on ten images. Inter- and intra-observer, as well as pre- and post-IOP reduction values were compared using ANOVA and paired t-tests. Results:Fifteen glaucomatous and fifteen ocular hypertensive eyes (n=30) were included. Each observer examined a total of seventy images. The mean IOP reduction was 39 percent. The mean DA measurements showed no statistical difference between initial and redrawn disc outlines for all three observers (p≷0.1). When comparing all three examiners, inter-observer mean DA values were similar for both pre and post IOP reduction images (p=0.838, and p=0.922, ANOVA). Although there was a trend towards smaller DA measurements after IOP reduction (0.7-1.5%), these were not statistically significant (p=0.568, p=0.169, and p=0.063, from novice to most-experienced observer respectively). Conclusion:There is good intra- and inter-observer reliability for HRT DA measures. No statistically significant change in disc area measurements on HRT exams before and after large IOP reduction was found. These findings validate importing disc area contour lines from previous HRT exams.
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