What is a contraindication for using tricyclic antidepressants (TCAs)?

Narrow angle glaucoma is indeed a contraindication for the use of tricyclic antidepressants (TCAs). This is because TCAs can cause pupillary dilation, which may lead to increased intraocular pressure, worsening the condition in individuals with narrow angle glaucoma. Patients with this eye condition have an obstruction in the drainage of the aqueous humor in the eye, and the dilation can precipitate an acute attack, leading to severe pain and potential vision loss.

On the other hand, major depressive disorder and bipolar disorder are conditions for which TCAs might be prescribed, albeit with careful monitoring in the case of bipolar disorder to prevent manic episodes. Chronic insomnia is often treated with medications that can also include TCAs, though they are not typically the first-line treatment for insomnia alone. Therefore, contrary to the other options, narrow angle glaucoma poses a significant risk that contraindicates the use of TCAs.