Fundus Photography

Why photograph the retina

The examination through a dilated pupil shows the retina live, but memory and drawings are poor at detecting slow change. A photograph fixes the appearance of a hemorrhage, a drusen cluster, a pigmented lesion or the optic nerve's cup so that next year's image can be laid beside it. Progression of diabetic retinopathy, growth of a nevus, or subtle change in an optic nerve is far easier to judge from paired images than from recollection. The photographs also travel: they are sent to referring doctors and to specialists when a second opinion is needed.

The photograph

You rest your chin on the camera and look at a target while a flash captures the image, one eye at a time. Traditional cameras image the central retina and need a dilated pupil; wide-field systems capture most of the retina in a single image and often work through a small pupil. The flash is bright but brief, and the after-image fades in a minute.

What it is used for

• Diabetic eye exams: grading retinopathy and comparing year to year
• Macular degeneration: documenting drusen and pigment change
• Glaucoma: recording the optic nerve head for comparison alongside OCT
• Retinal nevi, freckles and other lesions that need monitoring for change
• Hypertensive and vascular changes in the retina
• Documentation before and after retinal treatment

Photography and OCT together

A photograph shows the retinal surface in color; OCT shows the layers beneath it in cross section. A macular photograph records the extent of drusen, while OCT shows whether fluid has appeared under them. The two are ordered together in most retinal conditions.