What is the clinical significance of pupillary dilation in a patient taking fluoxetine (selective serotonin reuptake inhibitor) without visual symptoms, and is it a potential indicator of predisposition to angle closure glaucoma?

From the Guidelines

I would recommend continuing fluoxetine while awaiting the ophthalmology evaluation, as pupillary dilation alone without visual symptoms is not typically a reason to discontinue the medication. Fluoxetine can occasionally cause mydriasis (pupil dilation) due to its serotonergic effects, but this is generally not indicative of angle closure glaucoma risk, as noted in the context of primary angle-closure disease 1. True angle closure glaucoma presents with eye pain, blurred vision, halos around lights, nausea, and headache - symptoms your patient is not experiencing.

Key Considerations

• The patient's symptoms do not align with those of angle closure glaucoma, which includes eye pain, blurred vision, and other visual disturbances 1.
• Pupillary dilation alone, without other symptoms, is not a definitive indicator of angle closure glaucoma risk.
• The ophthalmology evaluation is crucial to assess for any anatomical predisposition to angle closure, such as narrow angles.

Management Approach

• If the eye exam reveals narrow angles, consider switching to an alternative antidepressant with less anticholinergic activity, such as sertraline or escitalopram.
• Document the pupillary changes and ophthalmology findings in the patient's chart.
• Ensure follow-up after the eye appointment to review any recommendations from the ophthalmologist.
• Reassure the patient that isolated pupillary dilation without other symptoms is generally not concerning but warrants the evaluation they've already scheduled, based on the most recent guidelines for primary angle-closure disease management 1.

From the Research

Pupillary Dilation and Fluoxetine

• Pupillary dilation is a potential side effect of fluoxetine, a selective serotonin reuptake inhibitor (SSRI) 2, 3.
• SSRIs, including fluoxetine, can cause mydriasis, which may promote closure of angles in susceptible patients, potentially leading to angle-closure glaucoma 2, 3.
• The risk of angle-closure glaucoma is higher in patients with narrow iridocorneal angles, which are more common in people with hypermetropia, older individuals, and those with an Asian background 4, 5.

Angle-Closure Glaucoma Risk

• Recent exposure to antidepressant drugs, including SSRIs like fluoxetine, has been associated with an increased risk of acute angle-closure glaucoma (AACG) 6.
• The odds ratio for any antidepressant exposure in the period immediately preceding AACG was 1.62 (95% confidence interval, 1.16-2.26) 6.
• Patients with predisposing factors, such as a shallow anterior chamber depth or short axial length, are at higher risk of developing AACG when taking certain medications, including SSRIs 4.

Management and Prevention

• Ophthalmological consultations should be considered before starting and during treatment with any SSRI in patients with glaucomatous risk factors, especially those who are elderly 3.
• A laser peripheral iridotomy may be beneficial for patients with narrow iridocorneal angles, either prophylactically or to relieve an acute angle-closure episode 5.
• Physicians prescribing SSRIs should be aware of their potentially sight-threatening adverse effects and inform patients of the warning symptoms, such as elevated intraocular pressure, headache, nausea, blurry vision, and halos around lights 4.