Essentials of Veterinary Ophthalmology. Kirk N. Gelatt

vision (penguin) and light conditions (owl). The scientific literature reports visual acuity values for numerous other species such as giraffes, elephants, rhinoceros and marsupials that are beyond the scope of this book.

      ^b Most articles report visual acuity in cycles/degree. These values have been converted to Snellen units by the author (R.O.) as most readers are more familiar with this latter scale. Values for Snellen acuity <20/200 have been rounded.

      ^c Anatomical methods of assessment include counting the density or cones and/or RGCs; electrophysiological methods are based on recordings of the pattern electroretinogram or pattern visual evoked potentials.