Dr Sanborn has written regarding 3 patients included in the Central Vein Occlusion Study who had bilateral occlusions at the time of their first visit to a physician.1 The protocol of the Central Vein Occlusion Study did not include an elaborate medical evaluation. The protocol does address the issue of including 2 eyes from the same patient by stating that only those patients who had central vein occlusion in both eyes at the time of the initial visit could be considered candidates to have both eyes included in the study. Eyes with the onset of central vein occlusion up to 12 months prior to the initial visit were eligible for the study. None of these 3 patients had the onset of central vein occlusion "simultaneously." However, in each instance, the individual eyes were deemed eligible and, therefore, investigators were permitted to include both eyes of these 3 study patients.
Clarkson JG, for the Central Vein Occlusion Study Group. Bilateral Central Retinal Vein Occlusions—Reply. Arch Ophthalmol. 1998;116(2):260-261. doi: