It would be churlish to be critical of this book. To have reached its fourth edition in 11 years, and have the previous edition reprinted three times suggests that it is doing something right. It is indeed a very useful reference book for optometrists and others with an involvement in optical science. The appeal to the student is its comprehensive nature: to have geometrical optics formulas alongside ocular anatomy makes it a daily companion. For the experienced practitioner too, it provides a concise reminder of dimly remembered definitions, and proof that there is always something new to learn. When I looked up the description given by colleagues of their method of measuring pupil size, I found …