Inter-observer agreement in clinical optic disc measurement using a modified 60 D lens

Abstract

SUMMARYPurpose: To assess the inter-observer agreement of the measurement of optic disc dimensions by two observers using a modified 60 dioptre (D) fundus examination lens. Method:The vertical disc and cup diameters of 29 eyes were measured by two independent observers using a 60 D lens modified by incorporation of a 0.1 millimetre scale graticule. The vertical cup/disc ratio was calcu lated. Inter-observer agreement was assessed by calcu lation of the inter-observer differences and by the weighted kappa statistic.Results: The two observers showed good agreement for the measurement of disc diameter (mean difference -0.04; range -0.04, 0.2) and for cup diameter (mean difference -0.03; range 0.3, 0.2). Closer agreement for the vertical cup/disc ratio was achieved (mean kappa 0.96; 95% confidence limits 0.90, 1.0). The 95% confidence limit for the mean inter-observer difference in cup/disc ratio was 0.11, suggesting that a change of > 0.1 in the assessment of the cup/disc ratio by this technique is significant at the 5% level. Conclusion: High inter-observer agreement of optic disc measurement can be achieved with this technique. The method has the potential to improve the clinical evaluation of the optic disc and the precision and accuracy of the clinical measurement of other fundal structures.

Agreement between ophthalmologists and optometrists in optic disc assessment: training implications for glaucoma co-management

“…While further refinement of standard clinical assessment may be possible where a measurement technique is combined with a slitlamp based examination method [7], it is important to emphasise the need for a standardised method of assessment and documentation in co-management [15]. We conclude that, although some optometrists are capable of making valid and reliable measurements of disc status, there are considerable differences in individual performance.…”

“…The problem of observer variability in clinical optic disc observation is recognised widely [3,7,8,10,11,13,14,16,17,19,20,21]. However, few studies have compared the reliability of observations made by optometrists with those of ophthalmologists, and the findings of the studies that have made such comparisons are somewhat contradictory [1,2,6,18].…”

Magnification-corrected indirect biomicroscopy of the optic nerve head

“…The slit-lamp biomicroscopic measurement of the optic disc diameter, using a double-aspheric fundus examination lens, shows an acceptable intraobserver and interobserver variability in routine clinical disc biometry [17,8].…”

Optic Disk Size and Glaucoma

“…1,2,4,5,13, 17,52,58,102,122,131,137,138,165,167,171,182 Systematic measurement error may occur depending on the instrument and technique used. The size of an optic disk image is dependent on instrument magnification and the magnification properties of the eye.…”