Af. Spencer et Sa. Vernon, REPEATABILITY AND REPRODUCIBILITY OF OPTIC DISC MEASUREMENT WITH THE ZEISS 4-MIRROR CONTACT-LENS, Ophthalmology, 103(1), 1996, pp. 163-167
Background: A simple clinical quantitative method of optic disc diamet
er measurement using a 4-mirror gonioscope contact lens has been descr
ibed recently. Methods: Intraobserver and interobserver variations are
assessed on 77 eyes of 41 patients. Of these eyes, 63 had refractive
errors within 3 diopters of emmetropia. The disc was measured by proje
cting a slit beam of known height onto the disc. Results: Intraobserve
r variation: the coefficient of variation was 3.04% for observer 1 (ex
perienced) and 4.76% for observer 2 (novice) The mean of the three mea
surements by the two observers was not significantly different (P = 0.
2318). For observer 1, the mean variance of the eyes with higher refra
ctive errors did not differ significantly from the eyes with lower ref
ractive errors. Interobserver variation: the coefficient of variation
was 4.52%. The measurements for the novice were slightly larger for th
e smallest discs and slightly smaller for the largest discs (regressio
n analysis P = 0.0209). Conclusion: Repeatability and reproducibility
for this method are comparable with other methods of measurement. Unti
l experienced with the technique, the authors recommend that the mean
of three readings is used.