Fundus photography

Fundus photographs of the right eye (left image) and left eye (right image), seen from front so that left in each image is to the person's right. Each fundus has no sign of disease or pathology. The gaze is into the camera, so in each picture the macula is in the center of the image, and the optic disk is located towards the nose. Both optic disks have some pigmentation at the perimeter of the lateral side, which is considered non-pathological.

The left image (right eye) shows lighter areas close to larger vessels, which is regarded as a normal finding in younger people.

Fundus photography (also called fundography^[1]) is the creation of a photograph of the interior surface of the eye, including the retina, optic disc, macula, and posterior pole (i.e. the fundus).^[2][3]

Fundus photography is used by optometrists, ophthalmologists, and trained medical professionals for monitoring progression of a disease, diagnosis of a disease (combined with retinal angiography), or in screening programs, where the photos can be analysed later.

Compared to ophthalmoscopy, fundus photography generally needs a considerably larger instrument, but has the advantage of availing the image to be examined by a specialist at another location and/or time, as well as providing photo documentation for future reference. Modern fundus photographs generally recreate considerably larger areas of the fundus than what can be seen at any one time with handheld ophthalmoscopes.

Instruments and techniques

Fundus photography is performed by a fundus camera, which basically consists of a specialized low power microscope with an attached camera.

Practical instruments for fundus photography perform the following modes of examination:

• Color, where the retina is illuminated by white light and examined in full color.
• Red-free, where the imaging light is filtered to remove red colors, improving contrast of vessels and other structures.
• Angiography, where the vessels are brought into high contrast by intravenous injection of a fluorescent dye. The retina is illuminated with an excitation color which fluoresces light of another color where the dye is present. By filtering to exclude the excitation color and pass the fluorescent color, a very high-contrast image of the vessels is produced. Shooting a timed sequence of photographs of the progression of the dye into the vessels reveals the flow dynamics and related pathologies. Specific methods include sodium fluorescein angiography (abbreviated FA or FAG) and indocyanine green (abbreviated ICG) angiography.

Indications

Fundus photography is used to detect and evaluate symptoms of retinal detachment or eye diseases such as glaucoma.

In patients with headaches, the finding of swollen optic discs, or papilledema, on fundus photography is a key sign, as this indicates raised intracranial pressure (ICP) which could be due to hydrocephalus, benign intracranial hypertension (aka pseudotumor cerebri) or brain tumor, amongst other conditions. Cupped optic discs are seen in glaucoma.

In patients with diabetes mellitus, regular fundus examinations (once every 6 months to 1 year) are important to screen for diabetic retinopathy as visual loss due to diabetes can be prevented by retinal laser treatment if retinopathy is spotted early.

In arterial hypertension, hypertensive changes of the retina closely mimic those in the brain, and may predict cerebrovascular accidents (strokes).

See also

• Dilated fundus examination
• Optical coherence tomography, commonly used for imaging the structure of the retina

References

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