(HealthDay News) — Community optometrists have moderate inter-observer agreement for grading limbal anterior chamber depth (LACD), while equivalent agreement is seen for specialist optometrists and ophthalmologists, according to a study published in the March issue of Ophthalmic & Physiological Optics.

Anish Jindal, OD, from City University London, and colleagues conducted a two-phase study to assess inter-observer agreement for measuring LACD. In the first phase, 100 U.K. community optometrists graded eight digital slit-lamp images of anterior chamber angles using the original van Herick four-point grading scale. In the second phase, LACD of the right eye was graded by hospital-based glaucoma specialist optometrists and glaucoma subspecialist ophthalmologists using a seven-point percentage grading scale in 57 patients with suspected glaucoma.

The researchers observed moderate inter-observer agreement for community optometrists, with a mean weighted kappa (κw) of 0.50 for grading photographic images. Ninety-two percent of observations were within one grade of the actual grade, but there was a 13% false negative error rate for grading of narrow angles. Pairwise comparisons between optometrists and ophthalmologists in phase 2 showed moderate to substantial agreement (mean κw, 0.54 to 0.65), with a false negative rate of 1.9%. Equivalent grading accuracy was seen for specialist optometrists and ophthalmologists.

“The augmented seven-point percentage grading scale is intuitive and potentially offers greater accuracy for grading narrow angles than the traditional four-point scale for grading LACD,” the authors write.

The study was partially funded by a grant from Pfizer Ophthalmology.

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