Hypotony following the use of topical carbonic anhydrase inhibitors in glaucoma patients: a case report and review of literature

Introduction and importance: Topical carbonic anhydrase inhibitors (CAIs) are widely used to lower intraocular pressure (IOP) by suppressing aqueous production. Though generally safe, hypotony is an extremely rare adverse effect. Understanding, this reaction is clinically relevant, particularly in surgically complex glaucoma eyes. Case presentation: We report a monocular 70-year-old patient with congenital glaucoma who developed marked hypotony shortly after initiating topical dorzolamide 2%. The patient presented with blurry vision and ocular discomfort, with examination showing an IOP of 4 mm Hg measured using Goldmann applanation tonometry. Ancillary imaging ruled out cyclodialysis cleft and choroidal or retinal pathology. Clinical discussion: Dorzolamide was immediately discontinued, resulting in the complete recovery of IOP to 18 mm Hg within 2 weeks, while other antiglaucoma medications were continued unchanged. Subsequent exposure to other CAIs resulted in similar hypotensive responses, supporting a medication-related mechanism. No hypotony maculopathy or structural complications developed. Conclusion: This case underscores the importance of considering CAI-induced hypotony in patients with prior glaucoma surgeries or prolonged low IOP. Early recognition and prompt medication withdrawal can prevent permanent structural damage and preserve vision. The accompanying literature review highlights CAIs, particularly dorzolamide, as a rare but significant cause of hypotony.