Acute Angle Closure in Knobloch Syndrome.

We report cases of acute angle closure in 2 young highly myopic siblings with Knobloch syndrome. To our knowledge, this is the first report of acute angle closure in Knobloch syndrome. Both patients were homozygous for a likely pathogenic variant in COL18A1. Both responded to treatment with cyclophotocoagulation and remained stable despite declining or being medically unfit for clear lens extraction. We argue that the recent implication of heterozygous mutations in COL18A1 in familial angle closure supports the argument that acute angle closure in these 2 patients was likely to be a thus far unreported feature of Knobloch syndrome. In addition, these cases also support the hypothesis that pathogenic variants in COL18A1 may be a risk factor for acute angle closure.