A new method of quantifying the anterior chamber angle with Ultrasound Biomicroscopy (UBM)

H. Ishikawa, K. Esaki, J. M. Liebmann, Z. Stegman, Y. Uji, R. Ritch

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Purpose. To develop a method of quantifying the iridocorneal angle recess area (ARA) using UBM. Previously reported methods of quantifying angle information did not account for the variability of iris surface curvature. Method. The position of the scleral spur as detected by UBM was defined as the innermost point of a line separating ciliary muscle and scleral fibers. A perpendicular was drawn from a point on the corneal endothelium 750 μm anterior to the scleral spur to the iris surface. The ARA was defined as the triangle demarcated by this line. Area measurements were achieved in each quadrant for each image using a custom-designed program capable of tracing irregular borders. To assess ARA measurement reproducibility, two independent observers located scleral spur on 10 identical images of each eye in random order. Results. Mean patient age was 23.6 yrs, refractive error -0.50 D, and axial length 23.7 mm. Intraobserver measurement reproducibility was high (mean CV = 2.73% and 2.84% for the two observers). Although the mean p-value indicated no difference between observers (p=0.21), significant differences in interobserver reliability were found to exist in individual quadrants. Small differences in the assessment of scleral spur location contributed to disparity between the observers. Conclusion. ARA can be reliably measured using this method.

Original languageEnglish
Pages (from-to)S820
JournalInvestigative Ophthalmology and Visual Science
Volume37
Issue number3
StatePublished - 15 Feb 1996
Externally publishedYes

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