OPTIC DISC MEASUREMENT - A COMPARISON OF INDIRECT OPHTHALMOSCOPIC METHODS

Aims-Two methods of indirect-ophthalmoscopic estimation of optic disc size, the 78 dioptre lens and optic disc biometer were evaluated. Meth ods-Twenty nine eyes of 29 patients were measured by both methods and compared with optic disc size calculated using the three planimetric c orrections described by Bengtsson and Krakau. Results-The closest agre ement with the clinical measurements was found using correction 3. The re 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 als o a significant difference between the two clinical methods (p<0.0001) . Both methods showed acceptable intraobserver variation (GoV 2.45% an d 3.13% respectively) . Conclusion-Overall, both methods give larger m easurements 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 d isc size when compared with planimetry.