Hypotony-related complications, not numerical hypotony, should alarm the clinician

Chronic hypotony, defined as a pressure of ≤5 mmHg for >3 months, may occur after glaucoma surgery (1,2). Despite being traditionally regarded as a criterion for failure in clinical studies, chronic hypotony causes vision loss in a minority of patients (1).

Hypotony complications, such as macular folds and choroidals, may threaten the vision. Risk factors for developing hypotony complications include young age, male gender, high myopia, and previous vitreoretinal surgery (3-5). In predisposed eyes, hypotony complications may occur even in the absence of numerical hypotony, suggesting that numerical hypotony is not sufficient nor necessary to develop complications (5).

While chronic hypotony does not mean clinical failure per se, hypotony complications may lead to poor outcomes.

Contributor: Alessandro Rabiolo, MD FEBO,Glaucoma Fellow, Moorfields Eye Hospital, London

References
1. Tseng VL, Kim CH, Romero PT, et al. Risk Factors and Long-Term Outcomes in Patients with Low Intraocular Pressure after Trabeculectomy. Ophthalmology 2017;124(10):1457-65 doi: 10.1016/j.ophtha.2017.05.014Online First: Epub Date|.
2. Yun S, Chua B, Clement CI. Does Chronic Hypotony following Trabeculectomy Represent Treatment Failure? J Curr Glaucoma Pract 2015;9(1):12-5 doi: 10.5005/jp-journals-10008-1176Online First: Epub Date|.
3. Fannin LA, Schiffman JC, Budenz DL. Risk factors for hypotony maculopathy. Ophthalmology 2003;110(6):1185-91 doi: 10.1016/S0161-6420(03)00227- 6Online First: Epub Date|.
4. Saeedi OJ, Jefferys JL, Solus JF, Jampel HD, Quigley HA. Risk factors for adverse consequences of low intraocular pressure after trabeculectomy. J Glaucoma 2014;23(1):e60-8 doi: 10.1097/IJG.0000000000000008Online First: Epub Date|.
5. Rabiolo A, Leadbetter D, Anand N. Hypotony-associated Complications After Deep Sclerectomy: Incidence, Risk Factors, and Long-term Outcomes. J Glaucoma 2021;30(7):e314-e26 doi: 10.1097/IJG.0000000000001882Online First: Epub Date|.

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