Can This Patient Use Intranasal Corticosteroids (INCS)?
Yes, this patient can safely use intranasal corticosteroids (INCS) - the concern about her "narrow drainage tube" (trabeculectomy) relates to intraocular corticosteroids, not intranasal formulations, which have negligible systemic absorption and minimal risk of affecting intraocular pressure.
Understanding the Clinical Context
The patient's "narrow drainage tube" refers to a trabeculectomy, a glaucoma filtration surgery that creates an alternative drainage pathway for aqueous humor. The ophthalmology referral is to assess whether she has glaucoma or is at risk for elevated intraocular pressure (IOP).
Why INCS Are Safe in This Context
The critical distinction is between topical/intraocular corticosteroids versus intranasal corticosteroids:
Intraocular and topical ophthalmic corticosteroids carry significant risk of IOP elevation, particularly in patients with glaucoma or post-trabeculectomy. IOP elevations occur in a significant proportion of patients with prolonged corticosteroid use and require close monitoring 1.
Intranasal corticosteroids have minimal systemic bioavailability (typically <1-2%) and do not achieve clinically significant intraocular concentrations. They are not associated with the same IOP elevation risks as ophthalmic formulations.
Evidence Regarding Corticosteroid-Induced Ocular Hypertension
The risk hierarchy for steroid-induced IOP elevation is:
Highest risk: Intravitreal corticosteroids and corticosteroid implants, which are particularly associated with IOP elevations 2
High risk: Topical ophthalmic corticosteroids, which can cause IOP elevation in 17-36% of post-trabeculectomy patients 3. Steroid response can occur within the first 4 weeks after trabeculectomy 3.
Moderate risk: Prolonged systemic corticosteroids (oral/IV), which can cause severe corticosteroid-induced ocular hypertension requiring surgical intervention 4
Minimal to no risk: Intranasal corticosteroids, which lack sufficient systemic absorption to affect IOP
Post-Trabeculectomy Considerations
For patients who have undergone trabeculectomy:
Topical ophthalmic steroids are actually beneficial and superior to placebo in controlling IOP after trabeculectomy, with lower mean IOP (14.5 vs 19.3 mmHg) and better surgical success rates (94% vs 43%) at 5 years 5.
However, topical steroids must be carefully monitored and eventually tapered, as 23% of post-trabeculectomy eyes show steroid-induced IOP rise in the first 4 weeks 3.
The steroid response rate decreases over time, with only 3 of 8 previously responsive eyes showing persistent responsiveness on re-challenge 3.
Common Pitfalls to Avoid
Do not confuse intranasal corticosteroids with ophthalmic corticosteroids - they have entirely different risk profiles for IOP elevation.
Do not withhold necessary INCS therapy based on glaucoma history alone, as the systemic absorption is insufficient to cause clinically significant IOP changes.
Do ensure the patient avoids topical ophthalmic corticosteroids without ophthalmology supervision, as these carry genuine risk of IOP elevation, particularly in patients with compromised drainage (post-trabeculectomy, glaucoma) 1, 3.
Monitor for inadvertent ophthalmic steroid use - patients may not distinguish between nasal sprays and eye drops, so clear patient education is essential.
Practical Recommendation
Proceed with INCS as clinically indicated for the patient's nasal/sinus condition. Ensure she attends her ophthalmology appointment to assess baseline IOP and glaucoma status, but this should not delay or prevent appropriate INCS therapy. Document that you have counseled her to avoid topical ophthalmic corticosteroids without ophthalmology approval 1.