Structural correlations between brain magnetic resonance image‐derived phenotypes and retinal neuroanatomy by Sun, Z, Zhang, B, Smith, S, Atan, D, Khawaja, AP, Stuart, KV, Luben, RN, Biradar, MI, McGillivray, T, Patel, PJ, Khaw, PT, Petzold, A, Foster, PJ, the UK Biobank Eye and Vision Consortium