Which of the following is not a principal form of topical ophthalmic medication?

Topical ophthalmic medications are specifically formulated to be administered directly to the eye or surrounding areas to treat various ocular conditions. The principal forms of these medications typically include suspensions, ointments/gels, and inserts, all of which are designed for local application to the eye.

Pills, on the other hand, are systemic medications taken orally. They are not intended for local application and do not deliver medication directly to the eye. While oral medications can affect ocular conditions, they do so through systemic absorption and are not categorized as topical ophthalmic medications. Thus, the identification of pills as not being a principal form aligns with the intended administration routes for topical treatments specifically designed for eye care.