%0 Journal Article %A G. V. Catford %T Lecture Notes on Ophthalmology %D 1981 %R 10.1136/bjo.65.11.801-a %J British Journal of Ophthalmology %P 801-801 %V 65 %N 11 %U https://bjo.bmj.com/content/bjophthalmol/65/11/801.2.full.pdf