A physician and emergency equipment must be on hand. The dye goes into a vein, so the whole body receives it. Most patients feel nothing worse than momentary nausea. Rarely, a patient has a severe allergic reaction. Because that reaction can begin within seconds, help and supplies have to be in the room already. Fetching them after the dye is in is far too late.
The rest of the setup follows the purpose of the test. The camera carries special filters that make the dye glow as it fills the vessels. Pictures are taken in rapid sequence, so each one is timed. The test shows blocked vessels, leakage, and new vessel growth in the back of the eye. For that view the pupil must be dilated, not left small, so undilated pupils would ruin the study. Fasting and warming the dye are not textbook rules for this test. One allergy rule is worth knowing. Indocyanine green dye is usually easier to tolerate, but it is avoided in patients allergic to iodine or shellfish. That dye is used mainly to study the choroid, the vessel layer under the retina.
Treat every injected dye study as a small procedure. Dilate the pupil, warn the patient that she may feel briefly sick, and never start until the doctor and the emergency cart are there. Ask about past dye tests and past reactions before the needle is uncapped. Preparing a patient safely for dye photography belongs to the COA supplemental testing content area.
Incorrect Answers
- B. A long fast is not required for this study. Nausea can happen either way, and an empty stomach does nothing to prevent an allergic reaction to the dye.
- C. Fundus photography needs dilating eyedrops so the camera can see a wide field of retina. Small pupils would block the pictures, and the timed series could not be repeated later.
- D. Warming the dye is not a safety step in the textbook. It does nothing about the one real danger of the study, which is a sudden allergic reaction to the dye.
Testing Pearls
- Keep a physician and emergency equipment present for any injected dye study.
- Fluorescein can cause brief nausea and, rarely, a severe allergic reaction.
- Avoid indocyanine green in patients allergic to iodine or shellfish.
- Dilate the pupils before fundus photography of any kind.
- The study reveals blockage, leakage, and new vessel growth in fundus vessels.
References
- American Academy of Ophthalmology. Ophthalmic Medical Assisting: An Independent Study Course. Chapter 10, Adjunctive Tests and Procedures.
