Purchase this article with an account.
G. P. Williams, T. Saeed, S. T. Evans, S. J. Curnow, P. Nightingale, S. Rauz; Validation of a Fornix Depth Measurer in the Assessment of Ocular Mucous Membrane Pemphigoid Staging (ocMMP). Invest. Ophthalmol. Vis. Sci. 2009;50(13):1538.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Documentation of forniceal foreshortening in cicatrising conjunctivitis such as ocular Mucous Membrane Pemphigoid (ocMMP), is important in assessing disease stage and progression. We previously showed that lower fornix shortening is frequently documented subjectively or by utilising a slit-light beam; whereas the degree of upper forniceal obliteration is seldom assessed. Measurement of the fornices using tools such as the fornix depth measurer (FDM) have been described, but their current design limits upper fornix measurement. The purpose of this study was to custom-design a FDM to evaluate the upper fornix, and to assess intra- and inter-observer variability in gauging lower fornix depth.
A polymethylmethacrylate FDM was constructed using industry-standard jewellery software and machinery. Independent evaluation of central lower fornix depth in patient’s with/without ocular-surface inflammatory diseases was undertaken by 2 observers. Percentage loss of lower fornix was estimated subjectively, and calculated with the FDM (in mm and corrected to published age-specific lower fornix depths in normal eyes). Upper central fornix depth was also measured. All readings were in triplicate, and agreement calculated using the Bland-Altman comparison.
51 eyes were evaluated. There was 100% intra-observer agreement to within 1mm for each observer for lower and upper fornix measurement. The mean difference in % fornix depth measurement using the FDM for observer 1 and 2 was 1.19% and with a continuity correction, the 95% limits of agreement were between -15 and + 20%. 86% (44/51) measurements taken by the two observers agreed by +/-10% of total lower fornix depth (i.e. approx. ±1mm). Only 63% (32/51) of the subjective measurements by two observers agreed by ±10% of total lower fornix depth. For the upper fornix, 92% (47/51) of measurements by two observers were within ±2 mm i.e. approx ±10% of the total fornix depth.
Determining disease progression in cicatrising conjunctivitides such as ocMMP relies upon accurate documentation of disease in particular, shrinkage of the fornices. Our custom-designed FDM is well tolerated by patients. The FDM demonstrates low intra- and inter-observer variability enabling repeatable and reproducible measurements of lower fornix depths. Furthermore, it has potential to measure upper fornix depth, currently not routinely employed in clinical assessment.
This PDF is available to Subscribers Only