Considerations for randomizing 1 eye or 2 eyes

Evaluation of the presence of double-organ bias in published randomised controlled dacryocystorhinostomy studies

OBJECTIVE

The aim of this study is to show whether journals pay attention to double-organ bias in studies on dacryocystorhinostomy (DCR) treatment. Most statistical tests are based on the assumption that each data entry is independent of the other. However, we wanted to understand whether the eye, which is a double organ in the human body, is a cause of bias and whether sufficient attention has been paid to it in published articles.

DESIGN

A PubMed search was conducted between November 1997 and November 2021 in the field of ophthalmology and otolaryngology with the terms 'dacryocystorhinostomy' and the limitations of 'people' and 'randomly controlled studies'. Publications containing DCR were searched. The publications published in the 15 journals with the highest impact were selected. The scope of the journal, the scope of the authors, the relevance of the articles, the presence of randomisation, the type of study (drug, endoscopic surgery, laser surgery and external surgery) and the statistical approach to bilateral organ bias were evaluated by two independent observers.

RESULTS AND MAIN OUTCOME MEASURES

A total of 83 publications were found by Pubmed search. Fifty-six publications were included in the study. Double-organ bias was present in 41% (n = 23) of the cases. Of the 23 biased publications, 46.4% were found to be in the Quartile 1 group. Quartile 4 journals showed bias in only four journals.

CONCLUSION

Double-organ bias can also be seen in journals with high impact factors and published in recent years. Journals may need to pay more attention to double-organ bias in the publication acceptance process.

Endpoints for clinical trials in ophthalmology

With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.