If, in the routine examination of eyes, systematic tests are made of ocular muscle balance, anomalies of convergence and divergence are often found. Paralysis of divergence, however, is a condition which appears infrequently. In the available literature there are fifty recorded cases. When one considers that nine were seen by Duane1 and nine by Alger,2 the condition cannot be so rare as the small number of reported cases would indicate. It is possible that many are overlooked and pass unrecognized, because little reference to this subject is made in textbooks of ophthalmology and neurology.
The occurrence of this unusual paralysis in two members of a family (father and daughter) is mentioned in the literature by Stoelting.3 It seems a rather curious coincidence that the patients in two of the cases reported here are sisters (cases 1 and 2). The patient in case 3 had had paralysis