Gene therapy for glaucoma

Gene editing could be used to treat millions of glaucoma patients. Glaucoma is a leading cause of blindness, characterized by high pressure inside the eye. Patients often rely on daily eye drops to lower intraocular pressure, but the drops may cause significant complications including bradycardia, metabolic acidosis, and kidney stones. In addition, many patients fail to keep up with the eye drops. Yang Sun and colleagues used the CRISPR gene editing technique to knock down two genes associated with the production of aqueous humor—the fluid inside the eye—in mice. Specifically, the authors used Cas13d, one of a family of RNA-targeting CRISPR effectors, to edit mRNAs coding for aquaporin 1 (AQP1) and carbonic anhydrase type 2 (CA2) in the ciliary bodies of mouse eyes. Cas13d-treated mice had significantly lower intraocular pressure than untreated control mice in both wild-type and glaucoma mouse models. The gene editing treatment does not permanently change the DNA of eye cells, and thus is reversible and adjustable. According to the authors, to develop a treatment for humans, timing, dosage, and a noninvasive administration method would have to be worked out. The treatment would likely be required only monthly or even less often.