To describe methods that can be used to quantify and compare harm caused by surgical interventions in ophthalmology trials.

Perspective study.

A published landmark glaucoma trial was used as an exemplar. A consensus-derived classification system of severity of complications was applied to published data of the Tube Versus Trabeculectomy glaucoma trial. The severity grade of each complication was multiplied to the number of patients who incurred that complication to estimate a total harm score for each intervention. Graphical tools were also used to display the differences in complications between trial arms. A review of literature on best practice for reporting harm data was also conducted.

Analyzing treatment harm is challenging with the relatively small number of events and sample sizes used in randomized controlled trials. However, quantification and graphical representation of harm after surgery is possible. Reframing the research question to one for detecting signals of adverse reactions and use of Bayesian analyses can be useful.

Analysis of harm data in clinical trials needs further attention. A severity classification system and a total harm score can be used to quantify harm after glaucoma surgery. Graphical tools can also help interpret complication data.