Fig. 4. Dimensions of optic disc and relationship between disc and center of the fovea. Average dimensions and standard deviations given in millimeters. (Straatsma BR, Foos RY, Spencer LM: The retina: Topography and clinical correlations. In: Transactions of the New Orleans Academy of Ophthalmology: Symposium on Retina and Retinal Surgery. St Louis: CV Mosby, 1969.)