Optometry Research Today is a free monthly online journal that collates and summarizes the latest research about Optometry, including details on myopia, optometric practice, therapy.

Technical Note: grading the vertical cup:disc ratio and the effect of scaling.

Bennett R, Spry PG, Fenerty CH, Harper RA

Ophthalmology Department, Nottingham University Hospitals NHS Trust, Nottingham NG7 2UH, UK.

PURPOSE: To evaluate the effect of scaling on sensitivity to change for grading the vertical cup:disc ratio (CDR). METHODS: Vertical CDR was assessed by six observers (three ophthalmologists and three optometrists) on 43 stereo disc photographs. Repeated observations were made for both 0.1 and 0.05 interval scales. Paired differences were calculated for all observers and each observer separately. Mean and standard deviation of differences and agreement statistics were used to compare scales. RESULTS: Five observers demonstrated a reduction in the spread of differences (mean difference 0.19 to 0.15) and all observers demonstrated a reduction in concordance using the finer scale (mean concordance 54% to 39%). CONCLUSION: The use of a finer scale reduces test-retest variability and increases sensitivity to change when estimating the vertical CDR. Use of this scale does not require any additional resource and it may be easily implemented in routine clinical practice.

Published 24 October 2007 in Ophthalmic Physiol Opt, 27(6): 619-25.
Full-text of this article is available online (may require subscription).

© 2005-2008 Optometry Research Today. All Rights Reserved.