Abstract
The use of the 90 dioptre fundus lens in conjunction with slit-lamp biomicroscopy as a method of estimating optic size was evaluated in a series of 37 patients. The measurements taken from the Haag-Streit slit-lamp were compared with values obtained planimetrically in order to assess a conversion factor and also the reliability of the method. This technique is a quick and easy method of obtaining an estimate of optic nerve head size in the clinic, but cannot replace more accurate methods of optic disc planimetry.