TY - JOUR T1 - Optic disc measurement: a comparison of indirect ophthalmoscopic methods. JF - British Journal of Ophthalmology JO - Br J Ophthalmol SP - 910 LP - 915 DO - 10.1136/bjo.79.10.910 VL - 79 IS - 10 AU - A F Spencer AU - S A Vernon Y1 - 1995/10/01 UR - http://bjo.bmj.com/content/79/10/910.abstract N2 - AIMS--Two methods of indirect ophthalmoscopic estimation of optic disc size, the 78 dioptre lens and optic disc biometer were evaluated. METHODS--Twenty nine eyes of 29 patients were measured by both methods and compared with optic disc size calculated using the three planimetric corrections described by Bengtsson and Krakau. RESULTS--The closest agreement with the clinical measurements was found using correction 3. There was a significant difference between both the 78 D lens (p < 0.0001) and the biometer (p = 0.0027) and the planimetric results. There was also a significant difference between the two clinical methods (p < 0.0001). Both methods showed acceptable intraobserver variation (CoV 2.45% and 3.13% respectively). CONCLUSION--Overall, both methods give larger measurements than planimetry; the 78 D lens by 0.41 mm and the biometer by 0.15 mm. Neither method gives a satisfactory estimation of optic disc size when compared with planimetry. ER -