A 58-year-old client with type 2 diabetes mellitus is scheduled for fluorescein angiography to assess for diabetic retinopathy progression. Which instruction should the nurse provide to the client before the procedure?

Informing about allergies, especially to iodine or shellfish, is crucial due to risk of allergic reactions to fluorescein dye. Other instructions like fasting or avoiding bright lights are not typically required.

Understanding Fluorescein Angiography
Fluorescein angiography is a diagnostic procedure used to evaluate the blood vessels in the retina and choroid. A water-soluble dye called fluorescein is injected intravenously, typically into an arm vein. As the dye circulates through the retinal vasculature, a specialized camera with appropriate filters takes serial photographs. This allows the healthcare provider to visualize blood flow, identify areas of ischemia, detect microaneurysms, and pinpoint abnormal vessel growth such as neovascularization, which is a hallmark of proliferative diabetic retinopathy ^[1]. The procedure is critical for staging diabetic retinopathy and guiding treatment decisions to prevent vision loss.

Analyzing the Correct Instruction
The most critical pre-procedure safety check is a thorough allergy assessment, making option 3 the correct instruction. The nurse must specifically ask about allergies, with a focus on iodine and shellfish.

Why the focus on iodine and shellfish?
This is a common point of confusion. The fluorescein dye used in this procedure is not an iodine-based radiocontrast agent like those used in CT scans or cardiac catheterization. However, a documented allergy to iodine or shellfish is a crucial piece of information to report. The clinical significance lies in the fact that a history of a severe anaphylactic reaction to any substance identifies a patient who is at a generally higher risk for hypersensitivity reactions to other injectable agents, including fluorescein. While the molecular structures are different, the patient's predisposition to a severe immune response is the key safety concern. The healthcare provider will use this information to weigh the risks and benefits, and to ensure that emergency resuscitative equipment and medications are readily available before proceeding.

Why Other Options Are Not the Priority

Option 1: Inform the healthcare provider of any history of kidney stones.
This is not a primary concern for fluorescein angiography. Fluorescein dye is primarily metabolized by the liver and excreted by the kidneys, but it is not nephrotoxic and does not carry the same risk of contrast-induced nephropathy as iodinated contrast media. A history of kidney stones is not a contraindication to the procedure.

Option 2: Inform the healthcare provider of any history of glaucoma.
A history of glaucoma is important for many eye examinations, particularly those involving pupil dilation. While the pupil is often dilated for fluorescein angiography to improve the view of the retina, the procedure itself does not involve injecting dye into the eye or increasing intraocular pressure. The dye is injected into a peripheral vein, making a history of glaucoma a less critical pre-procedure safety check compared to a potential for an anaphylactic reaction.

Option 4: Inform the healthcare provider of any history of cataracts.
A cataract is an opacification of the eye's natural lens. While a dense cataract can physically obstruct the clinician's view of the retina, making the images harder to interpret, it does not pose a safety risk to the patient during the injection of the fluorescein dye. This is a consideration for image quality, not a pre-procedure safety instruction that takes precedence over allergy assessment.

The core nursing responsibility before any procedure involving an injectable agent is to identify potential risks for a hypersensitivity reaction. A reported allergy to iodine or shellfish serves as a critical red flag for a patient who may be atopic and prone to severe reactions, necessitating heightened vigilance and preparation .