Figure 1 shows a well-defined flat, round, yellow lesion inferior to the optic disc and approximately 1.5 disc diameters in size. This is the appearance of the left retina of an asymptomatic 28-year-old man with good visual acuity (6/9 Snellen). The rest of his fundus was unremarkable. The right eye was normal. The differential diagnosis of such a lesion would include hard exudates; a mass lesion, for example, an osteoma; an inflammatory lesion such as a Toxoplasma or Toxocara scar; and retinal pigment epithelial atrophy