Delayed-Onset, Recurrent Hyphema after Microhook ab interno Trabeculotomy

Trabeculotomy (LOT) and related goniotomy surgeries can be divided into two classes based on the excision or incision of the trabecular meshwork. Previously, blood reflux from Schlemm’s canal (SC) after long-standing glaucoma surgery was reported in eyes treated with excisional LOT. The current case is one of delayed-onset hyphema after incisional LOT. An 87-year-old woman with bilateral normal-tension glaucoma had undergone microhook ab interno LOT (μLOT) combined with small incisional cataract surgery in both eyes 4 years previously. At the scheduled 4-year follow-up visit, numerous red blood cells floating in the anterior chamber, angle hyphema, and opening of the LOT cleft were observed in the right eye. No possible cause of hyphema such as rubeosis, Swan syndrome, or uveitis-glaucoma-hyphema syndrome was identified. This case suggests that SC can remain open for an extended time even after incisional LOT such as μLOT.