Acute Primary Angle Closure Caused by Plateau Iris after Ritodrine Use in a Primigravid Woman Successfully Treated with Clear-Lens Extraction: A Case Report

Acute primary angle closure (APAC) is rare in young adults (those under approximately 40 years old) and pregnant women. Here, we report the case of a 37-year-old primigravid woman with APAC caused by plateau iris after the use of ritodrine (a β2 stimulator) that was successfully resolved by clear-lens extraction five months after delivery. The patient presented with pain in her right eye after ritodrine infusion for threatened premature labor at 23 weeks of gestation. Her visual acuity was 20/40, and her intraocular pressure (IOP) was 31 mmHg in her right eye. The patient was diagnosed as having APAC with plateau iris based on ultrasound biomicroscopy (UBM) findings of irido-angle touch, anterior dislocation of the ciliary process, and an absent ciliary sulcus. The effectiveness of treatment with pilocarpine eyedrops was limited, and argon laser peripheral iridoplasty did not succeed in reducing IOP. An immediate resolution was achieved with clear-lens extraction. IOP has since stayed within 14-16 mmHg without any medication for seven years. This is the first reported case of APAC complicated with plateau iris after ritodrine use in a pregnant woman. This condition is rare in young adults, making it difficult to diagnose; however, UBM can be of great help. In this case, clear-lens extraction led to a successful outcome. Our case suggests that attention should be paid to drug associations when APAC occurs with plateau iris.