8.2 Mydriatics, Cycloplegics & Diagnostic Ophthalmic Dyes

Mydriatics, Cycloplegics, and Diagnostic Dyes

Retina examinations often require dilation and sometimes angiographic contrast. These products are medications, not routine supplies. A technician works from an order or approved protocol and considers the patient's history, current drugs, anatomy, and prior reactions before instillation or injection.

Mydriasis and cycloplegia

Tropicamide is an antimuscarinic drug commonly used for diagnostic dilation. It relaxes the iris sphincter and ciliary muscle, so it produces mydriasis and some cycloplegia. Onset and duration vary with concentration, pigmentation, age, and other drugs.

Phenylephrine is an alpha-1 agonist that contracts the iris dilator. It does not provide cycloplegia. Systemic absorption can affect blood pressure and heart rhythm, especially with higher concentrations or susceptible patients. Verify cardiovascular history, interacting drugs, and the ordered concentration; use punctal occlusion or eyelid closure when protocol calls for it to reduce systemic absorption.

Longer-acting cycloplegics such as cyclopentolate, homatropine, or atropine have different indications and durations. No single drop is the universal best choice for every retina visit. The prescriber or standing protocol determines selection.

Angle and neurologic safety

A shallow peripheral chamber on screening is a reason to pause and notify the clinician, not an independent diagnosis of angle closure. The clinician considers gonioscopy, prior iridotomy, symptoms, and the need for dilation. After drops, urgent symptoms such as severe pain, headache, halos, nausea, a fixed mid-dilated pupil, or sudden vision reduction require immediate escalation.

Document baseline pupils before dilation when a neurologic or afferent examination is needed. Record agent, concentration, eye, time, and response.

Sodium fluorescein

Topical fluorescein supports corneal staining and applanation. Intravenous sodium fluorescein is used for retinal angiography. Verify the correct route and formulation: a topical strip or drop is not an injectable product. IV fluorescein can cause nausea, vomiting, urticaria, extravasation, and rarely a severe systemic reaction. Check prior reaction details and emergency readiness. The clinician decides whether premedication, an alternative test, or cancellation is appropriate.

Indocyanine green

ICG absorbs and emits near-infrared light and is highly protein-bound, which supports choroidal imaging through pigment and some hemorrhage. Current U.S. IC-GREEN labeling says the product contains no more than five percent sodium iodide and should be used with caution in a patient with a history of allergy to iodides because of anaphylaxis risk. It also states that reactions may occur with or without such a history.

Shellfish allergy is directed at seafood proteins and is not, by itself, an iodine allergy or automatic contraindication to ICG. Ask what product caused the reaction, the route, symptoms, severity, timing, and treatment. A prior ICG reaction or relevant iodide history goes to the clinician for risk assessment. Pregnancy, hepatic disease, or other comorbidity likewise requires clinician review rather than a memorized universal exclusion.

Safe administration workflow

Before any ordered dye or drop:

1. use two patient identifiers and confirm the eye and study;
2. verify product, route, concentration, dose, lot, expiration, and container integrity;
3. reconcile allergies and prior reactions using specific descriptions;
4. confirm IV patency for injectable dye and check emergency equipment;
5. explain expected sensations and warning symptoms without promising that a reaction cannot occur;
6. document administration and any event.

For extravasation, stop injection and follow the product and facility protocol. For airway symptoms, hypotension, rapidly progressive swelling, or multisystem reaction, stop the study and activate the emergency response. Medication treatment follows the authorized emergency protocol.

The central exam distinction is mechanism plus safety: antimuscarinic versus adrenergic dilation, topical versus intravenous fluorescein, and visible-light fluorescein versus near-infrared ICG.

Medication checks and adverse-response workflow

Before instillation, compare the authorized order with the patient, eye, drug, concentration, route, expiration, allergies or prior reactions, and relevant precautions. Inspect the bottle and tip, perform hand hygiene, avoid touching the ocular surface, and document the agent and time. Do not reuse a single-patient container across patients or override a warning because the same drops were tolerated previously.

After drops, monitor according to the drug, patient risk, and clinic protocol. New chest pain, severe headache, dyspnea, marked blood-pressure change, confusion, or allergic symptoms require immediate escalation. Ocular pain, nausea, halos, or a red eye after dilation can signal an acute pressure problem and also needs urgent review. A technician may recognize a concerning pattern but does not diagnose angle closure or independently select a reversal drug. When the pupil dilates poorly, verify timing and technique and notify the clinician rather than repeatedly dosing outside the order.