Clinical biomarker in aqueous misdirection syndrome: The pupillary snap sign

Aqueous misdirection syndrome (AMS) is characterized by high intraocular pressure and a shallow anterior chamber because of anterior rotation of the ciliary processes, accumulation of aqueous within the anterior vitreous, and forward displacement of the iris–lens diaphragm (ILD). It mainly occurs in eyes with narrow iridocorneal angles, after intraocular surgery, after laser procedures, or after administration of topical miotics. There is no standardized therapy; however, zonulectomy–hyaloidectomy–anterior vitrectomy seems to be the most effective treatment. A neodymium:YAG (Nd:YAG) laser capsulotomy–hyaloidotomy is a more conservative approach that can decompress the anterior vitreous, release the aqueous, and promote backward displacement of the ILD. We present a case of AMS initially managed with Nd:YAG laser capsulotomy–hyaloidotomy. During this procedure, constriction and redilation of the pupil (ie, the pupil “snapped”) was observed, along with aqueous and vitreous prolapse in the anterior chamber. This sign might represent the moment of aqueous misdirection reversal and could be interpreted by the ophthalmologist as a useful clinical biomarker.