COLA18A probably plays a major role in determining the retinal structure as well as in the closure of the neural tube. Defects in COL18A1 are a cause of Knobloch syndrome type 1 (KNO1). An autosomal recessive disorder defined by the occurrence of high myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities and occipital encephalocele. Belongs to the multiplexin collagen family. 3 isoforms of the human protein are produced by alternative promoter. Note: This description may include information from UniProtKB.