What Is Fundus Photography?
Fundus photography captures high-resolution color images of the posterior segment of the eye -- the retina, optic disc, macula, and retinal blood vessels. These photographs serve as objective documentation of the retinal status at a specific point in time, allowing the doctor to monitor changes over repeated visits and communicate findings to specialists or insurance reviewers.
The CPOA typically captures fundus photographs as a routine part of the comprehensive eye examination or as a dedicated diagnostic test for patients with retinal disease, diabetes, hypertension, glaucoma, or other conditions requiring documentation.
Types of Fundus Cameras
Nonmydriatic Fundus Camera
The nonmydriatic camera is designed to photograph the retina through an undilated pupil using infrared alignment light and a brief flash to capture the image. Most modern fundus photography for screening and routine documentation uses nonmydriatic cameras.
- No dilation drops required -- faster workflow, less patient inconvenience.
- Captures a 45-degree field of view (standard) centered on the optic disc or macula.
- Image quality may be limited in patients with small pupils, dense cataracts, or poor media.
Mydriatic Fundus Camera
When the doctor orders mydriatic photography, dilating drops are instilled to widen the pupil (typically 6-8 mm) before imaging. This significantly improves image quality and allows wider-field photography. Required for detailed macular imaging, disc stereophotography, and documentation of subtle peripheral findings.
CPOA Role in Fundus Photography
Before Photography
- Determine if dilation is ordered: If mydriatic photography is ordered, instill dilating drops (tropicamide 1%, phenylephrine 2.5%) as directed and wait 15-30 minutes for full dilation before photographing.
- Dim the room: Low room lighting helps dilate the pupil naturally, even for nonmydriatic photography.
- Explain the procedure: "We are going to take pictures of the back of your eye. You will see a bright flash when the picture is taken -- this is normal and will not hurt your eye."
- Enter patient data: Name, date, and which eye(s) to photograph into the camera software.
Capturing Images
- Position the patient at the fundus camera with chin in chin rest and forehead against bar.
- Align the camera with the patient's pupil using the joystick -- the pupil reflex should appear centered in the camera's view.
- Focus the image using the internal focusing dial -- the retinal vessels should be sharp before taking the photo.
- For standard 2-field photography: capture one disc-centered image and one macula-centered image per eye.
- Review image quality immediately after capture. Check for adequate illumination, focus on the disc margin and macular reflex, absence of artifacts (lashes, blink artifacts, media opacity).
- Retake any substandard images before the patient leaves.
💡 Clinical Tip: Instruct the patient to look slightly in a specific direction to center different parts of the retina. For a disc-centered image, ask the patient to look directly at the internal fixation light. For a macula-centered image, ask the patient to look slightly inward (toward their nose on the side being photographed) to shift the macula into the center of the frame.
Normal Fundus Landmarks
Knowing what to expect in a normal fundus image helps the CPOA recognize obviously abnormal images that need to be flagged:
- Optic disc: Round to oval, well-defined margins, pink color with a central pale cup.
- Cup-to-disc ratio (CDR): The ratio of the central pale cup diameter to the total disc diameter. Normal is less than 0.5. A CDR greater than 0.6, or asymmetry between eyes, suggests glaucoma suspect.
- Macula: Located temporal to the disc. The foveal reflex (a bright pinpoint reflection at the center of the macula) should be visible in younger patients.
- Retinal vessels: Arteries (brighter red, narrower) and veins (darker, wider). Artery-to-vein ratio approximately 2:3.
⚠️ Common Mistake: Accepting an out-of-focus image because the patient was difficult to photograph. A blurry fundus photo cannot be evaluated clinically and effectively counts as no documentation. Take the time to refocus and recapture -- a sharp image is the minimum acceptable standard.
Documentation of Fundus Photos
- Store images in the patient's electronic health record linked to the correct eye and date.
- Note in the chart: "Fundus photos taken OD OS, 2-field, nonmydriatic" (or mydriatic if dilated).
- Flag any obviously abnormal findings for the doctor's immediate attention (flame hemorrhage, disc pallor, large cup, drusen, bright spots).
Key Takeaways
- Fundus photography documents the retina, optic disc, and macula for monitoring and diagnosis.
- Nonmydriatic cameras photograph without dilation; mydriatic cameras produce better quality with dilated pupils.
- The CPOA sets up the patient, aligns and focuses the camera, captures disc and macula-centered images, and reviews quality.
- Standard 2-field photography captures one disc-centered and one macula-centered image per eye.
- A normal disc is round, well-defined, pink with a central cup (CDR less than 0.5).
- Out-of-focus or artifactual images must be recaptured -- blurry photos have no clinical value.