Tetrahydrozoline Eye Drops Are NOT Recommended for Subconjunctival Hemorrhage
Tetrahydrozoline (THZ) eye drops should not be used for subconjunctival hemorrhage, as they can cause significant conjunctival toxicity and inflammation with chronic use, and subconjunctival hemorrhage is a self-limited benign condition that requires no active treatment beyond observation and reassurance. 1
Why Vasoconstrictors Are Inappropriate
Mechanism of Harm
- Chronic use of decongestant eye drops containing tetrahydrozoline causes three distinct patterns of conjunctival inflammation: conjunctival hyperemia (rebound redness), follicular conjunctivitis, and eczematoid blepharoconjunctivitis 1
- Patients using these preparations daily develop conjunctivitis after a median of 3 years of use, with symptoms taking a median of 4 weeks to resolve after discontinuation 1
- The pharmacological, toxic, and allergic mechanisms of these drops produce both acute and chronic forms of conjunctival inflammation 1
Natural History of Subconjunctival Hemorrhage
- Subconjunctival hemorrhage is a benign, self-limited disorder that resolves spontaneously without treatment 2
- The condition represents a common cause of acute ocular redness but poses no threat to vision or ocular health 2
- Major risk factors include trauma and contact lens use in younger patients, while hypertension, diabetes, and arteriosclerosis are more common causes in elderly patients 2
Appropriate Management Approach
Observation Only
- No topical medications are indicated for uncomplicated subconjunctival hemorrhage - the blood reabsorbs naturally over 1-3 weeks
- Artificial tears may be used if the patient experiences mild irritation, but preservative-free formulations are preferred to avoid ocular surface toxicity 3
When Further Evaluation Is Needed
- Recurrent or persistent subconjunctival hemorrhage warrants systemic evaluation including workup for hypertension, bleeding disorders, systemic and ocular malignancies, and medication side effects 2
- Long-term topical corticosteroid use substantially increases the prevalence of spontaneous subconjunctival hemorrhage due to steroid-induced vascular fragility 4
Important Clinical Caveat
While oxymetazoline (a different vasoconstrictor) has been studied for preventing subconjunctival hemorrhage during intravitreal injections when applied 30 minutes before the procedure 5, this is an entirely different clinical scenario than treating an established subconjunctival hemorrhage. The prophylactic use of vasoconstrictors before procedures does not translate to therapeutic benefit for existing hemorrhages.
Key Pitfall to Avoid
Do not prescribe "redness relief" drops for subconjunctival hemorrhage - patients may continue using these over-the-counter preparations chronically, leading to rebound hyperemia and chronic conjunctivitis that is far more problematic than the original benign hemorrhage 1