Why Drop Technique Matters
Improper drop instillation is one of the most common and underappreciated causes of treatment failure in ophthalmology. Studies consistently show that a significant proportion of patients -- including those who claim proficiency -- use incorrect technique. As a CPOA, teaching and verifying correct drop technique is one of the highest-impact patient education tasks you can perform. A drop that misses the eye is wasted medication, and touching the dropper to the eye introduces contamination.
Standard Drop Instillation Technique
The following steps describe optimal technique for instilling a topical ophthalmic drop:
- Wash hands thoroughly with soap and water before handling the drop bottle or touching the eye
- Shake the bottle if indicated (suspensions like prednisolone acetate require shaking; solutions do not)
- Position the patient: tilt head back, or have the patient lie supine. Looking up reduces the blink reflex.
- Create a pocket: gently pull down the lower eyelid with a clean finger to form the lower conjunctival fornix (the cul-de-sac)
- Instill one drop: hold the bottle 1-2 cm above the eye (not touching), squeeze gently, and allow one drop to fall into the conjunctival pocket. The patient should be looking up to avoid the drop landing on the cornea and triggering a blink.
- Close the eye gently -- do not squeeze or blink forcefully. Squeezing expels the drop from the eye.
- Punctal occlusion: with the eye closed, gently press the index finger at the medial corner of the eye (over the puncta) for 1-2 minutes. This reduces drainage through the nasolacrimal system into the nose, minimizing systemic absorption and maximizing ocular drug contact time.
- Blot excess from the eyelid margin with a clean tissue if needed
💡 Clinical Tip: The conjunctival sac holds only about 7-10 microliters. A typical eye drop is 35-50 microliters -- most of it overflows onto the cheek. Exactly one drop is sufficient; two drops do not double the drug delivery to the eye, they just increase systemic absorption via the nasolacrimal route.
Punctal Occlusion
Punctal occlusion (also called nasolacrimal occlusion or NLO) significantly reduces systemic absorption of topical ophthalmic medications. Drugs that are particularly important to occlude after instillation include:
- Timolol and other beta-blockers: systemic absorption can cause bradycardia, hypotension, and bronchospasm
- Brimonidine: systemic absorption can cause significant sedation, especially in young children
- Atropine: systemic absorption causes tachycardia, flushing, dry mouth
- Phenylephrine (10%): systemic absorption can cause significant blood pressure elevation
Instilling Multiple Drops
When multiple drops are required:
- Wait at least 5 minutes between drops. This allows the first drop to absorb before the second washes it out.
- If a gel or suspension (thicker) is being used along with a solution (thinner), instill the solution first, wait 5 minutes, then apply the gel or ointment. Viscous preparations instilled first can prevent absorption of subsequent drops.
- If applying ointment after drops, wait at least 10-15 minutes after the last drop.
⚠️ Common Mistake: Patients with multiple glaucoma drops often instill all of them in rapid succession. This is ineffective -- only the last drop remains in the eye at full concentration, and earlier drops are washed out. Educate patients to space drops by at least 5 minutes.
Ointment Application
Ophthalmic ointments (e.g., erythromycin, tobramycin, lubricating ointment) are applied to the lower conjunctival fornix:
- Pull down the lower lid to expose the fornix
- Apply a thin ribbon of ointment (about 0.5 cm) into the pocket, from inner to outer canthus
- Close the eye and gently roll the eyeball to spread the ointment
Ointments blur vision and are typically applied at bedtime for this reason. They provide longer drug contact time than drops.
Instilling Drops in Children
Instilling drops in children requires modification of technique:
- Have the child lie flat (reduces fear of falling) or sit in a caregiver's lap facing them
- Caregiver can hold the child's head between their knees while lying the child on their back
- For a child who will not open their eyes: place the drop in the inner canthal area (between the eyelids at the nose) -- when the child eventually opens their eye, the drop enters the conjunctival sac by capillary action
- Use punctal occlusion, especially with cyclopentolate or atropine, to reduce systemic effects
Bottle Contamination Prevention
- Never touch the dropper tip to the eye, eyelashes, or face
- Recap immediately after use
- Store as directed (some drops require refrigeration; check the label)
- Discard 4 weeks after opening (most multi-dose bottles, as per labeling) -- contamination risk increases over time
- Never share eye drops between patients or family members
Key Takeaways
- One drop is sufficient; the conjunctival sac holds 7-10 microliters; additional drops mostly overflow
- Look up, lower lid pulled down, drop into the pocket, close gently -- do not squeeze
- Punctal occlusion for 1-2 minutes after instillation reduces systemic absorption
- Wait 5 minutes between different drops; instill solutions before suspensions and ointments
- Never touch the dropper tip to the eye
- Discard opened multi-dose bottles after 4 weeks to prevent contamination