Clinical decision making in ophthalmology.

ecisions based on clinical examination are critical to the practice of ophthalmology. Although quite different disease processes can produce the same structural and functional outcomes, treatment decisions are often directly based on the observation of a complex of signs and symptoms. Thus, presented with a patient with sudden visual loss and/or ocular pain due to posterior uveitis, the ophthalmologist will rely on the clinical examination, in particular ophthal-moscopy, to answer three basic questions: what is wrong (diagnosis), what can we expect in the future (prognosis), and what can we do about it (effect of treatment)? But how reliable and accurate are oph-thalmoscopic observations and how useful is ophthalmoscopy to support therapeutic decisions? Stanford and co-workers, in a study published in this issue of the BJO (p 636), have tried to address some of these questions. They estimated the sensitivity and specificity of uveitis experts' interpretation of retinal photographs for the diagnosis of toxoplasma retinochoroiditis. Five experts were asked to classify the retinal photographs of 96 patients into four categories without any additional information (definitely, probably, possibly, or not toxoplasma retinochoroiditis). This is an important study as it is the first time that the diagnostic accuracy of these oph-thalmoscopic findings has been investigated. A major problem the investigators had to overcome was that it is not possible to diagnose or exclude the disease with certainty, and a statistical model was therefore used to estimate the sensitivity and specificity. The sensitivity and specifi-city were found to vary considerably among the experts, which led the authors to conclude that a considerable number of decisions to treat patients will be wrong if they are based on a single fundal examination. There are a number of broader issues that this study raises. Firstly, the most important aim of evaluating the signs and symptoms of patients is to identify those patients for whom the expected benefit of treatment outweighs the expected harm. For example , the best treatment for patients with toxoplasma retinochoroiditis is considered to be antibiotics in combination with systemic corticosteroids. As this treatment is associated with serious potential adverse effects, an accurate distinction between patients with and without toxo-plasma retinochoroiditis is of utmost importance. On reflection however, this " stepping stone approach " (jumping from complaints to diagnosis and then from diagnosis to treatment) is in many cases rather artificial. A more pragmatic approach seems to occur in clinical practice, when the role …