Just as different fads that seize the imagination of the general publi
c are often carried to excess, so diagnostic or therapeutic fads may t
ake over in the practice of medicine. Analysis of 33 surveys of the ca
uses of uveitis reported by ophthalmologists over the course of 120 ye
ars shows how some diagnoses such as syphilis and tuberculosis fell fr
om favor because tests ruled out these diseases, whereas others such a
s toxoplasmosis became popular because of the finding of the organism
in a few cases by a famous ophthalmic pathologist. Yet others (pars pl
anitis, sarcoidosis) were not even causes of disease, but rather merel
y descriptive, or the ocular component of a systemic disease whose eti
ology and pathogenesis remain unknown. We will examine the waxing and
waning of these diagnostic categories and the impressive confidence of
some clinicians in their own diagnostic acumen as they made diagnoses
often unsupported by objective evidence.