Late hypotony as a complication of viscocanalostomy: a case report

We report a long-term hypotony syndrome after deep sclerectomy, associated with intermittent rise in intraocular pressure (IOP) due to steroid response.

A 55-year-old woman with high myopia (RE -9.25, LE -10.50) suffering from uncontrolled pigment open-angle glaucoma, despite laser trabeculoplasty and a cyclodestructive procedure, underwent an uneventful viscocanalostomy.

Intraocular pressure was between 9 and 17 mm Hg with local steroid medication 5 times a day, but became unstable with steroid reduction to 3 times a day and the patient developed hypotonous IOP (3-5 mm Hg) in the fourth postoperative month. With intensification of local steroid therapy, IOP rose to 49 mm Hg, and a reduction in medication was followed by hypotony. The instability of IOP with steroid medication could not be controlled and the IOP response due to steroids diminished with time; a long-term hypotony syndrome with maculopathy developed. Surgical inspection 10 months later with repeated preparation of the scleral flap showed (like ultrasound biomicroscope examination) a normal status after viscocanalostomy, without signs of leakage.

Late hypotony syndrome should be considered as a potential complication of viscocanalostomy, perhaps especially in cases of myopia and former cyclodestructive procedures. In our case, despite nonpenetrating glaucoma surgery, the steroid response at first observed indicated additional outflow via the trabecular meshwork. After some months it could not be provoked any longer, leaving us to consider whether a gradual change in the trabecular meshwork hinders steroid medication changing aqueous outflow facility.