Cataract surgery is a common and successful procedure designed to restore vision by replacing the eye’s clouded lens. As with any surgical intervention, a period of fasting, known as “nil per os” (NPO), is required before the operation to ensure patient safety. Although the surgery is typically brief and often uses only local anesthesia, preparation rules regarding food and drink are specific and must be followed precisely. Adhering to these pre-operative instructions is necessary for a successful surgery and a smooth recovery.
Why Pre-Surgery Fasting Is Required
The primary reason for fasting before any procedure is to prevent a dangerous complication called pulmonary aspiration. Aspiration occurs when stomach contents, such as food or acidic fluids, are regurgitated and inhaled into the lungs. This can lead to severe issues, including aspiration pneumonia, which is difficult to treat and can be life-threatening.
Although most cataract surgeries use topical anesthesia or a local nerve block, a sedative is often given to help the patient relax and remain still. If a patient has food or fluid in their stomach while sedated, protective reflexes like coughing and swallowing are temporarily suppressed. This suppression increases the risk of stomach contents entering the airways. The fasting protocol is a universal safety standard applied to all patients undergoing procedures involving sedation or anesthesia.
Detailed Rules for Food and Drink
Standard guidelines for elective surgery recommend a specific two-part NPO protocol. For solid foods, including light meals, consumption must stop at least six hours before the scheduled procedure. This timeframe allows the stomach sufficient time to empty its contents completely.
A separate, shorter rule applies to clear liquids, which are allowed up to two hours before the procedure. Clear liquids include plain water, black coffee or tea without milk or cream, apple juice, and sports drinks without pulp. The stomach processes these liquids much faster than solids, making the two-hour window safe. Adhering to these minimum fasting times balances safety with avoiding prolonged dehydration or discomfort associated with the older “NPO after midnight” rule.
Managing Medications Before Surgery
Confusion often surrounds whether to take essential morning medications on the day of surgery. The general instruction for most regularly taken medications (e.g., those for blood pressure or cholesterol) is to take them as usual with a small sip of water. This is allowed because maintaining necessary blood levels outweighs the minimal risk posed by the water. However, specific classes of medications require adjustments and must be discussed with the surgical team beforehand. Blood thinners, such as aspirin, may need to be stopped several days prior to surgery to minimize bleeding, and diabetic medications must be carefully managed or skipped entirely, as fasting without adjusting the dosage can cause a dangerous drop in blood sugar.
What Happens If You Do Not Fast
Failing to follow the pre-operative fasting rules will result in the cancellation or postponement of the surgery, as the surgical center cannot proceed with sedation if the patient has recently consumed food or non-clear liquids. This is a non-negotiable safety precaution to protect the patient from the risk of pulmonary aspiration. The risk of aspiration is considered too serious to ignore for an elective procedure like cataract surgery. If a patient admits to eating or drinking outside the prescribed window, the procedure will be immediately rescheduled. This delay allows the stomach adequate time to empty, ensuring the patient can safely receive the necessary sedation or anesthesia on the new date.