A 52-year-old Indian man with hyperopia and shallow anterior chambers presents with recurrent episodes of transient blurred vision and mild eye discomfort, each lasting 1–2 hours and resolving spontaneously. Gonioscopy shows appositional angle closure without peripheral anterior synechiae. In contrast, his brother has a similar presentation but with permanent vision loss and fixed posterior synechiae on gonioscopy. Which finding best distinguishes the brother's condition (chronic angle-closure glaucoma) from the patient's condition (subacute/intermittent angle-closure)?