Nutcracker syndrome, 237 Nutritional anemias, 778 Nystagmus, 124 –125 , 157 , 159 –160 O Oasthouse urine disease, 333 Obstruction, 87 Obstructive shock history and physical examination findings, 76 POCUS findings, 76 Obstructive sleep apnea syndrome (OSAS), 960 –962 , 962 f Occlusion dermatitis, 463 Occult injury, 620 , 623 , 627 , 629 Occult pneumonia, 358 Occult spinal dysraphism, cutaneous manifestations, 1355 Ocular albinism, 465 Ocular chemical injury clinical assessment, 1400 clinical recognition, 1400 evidences, 1400 management, 1400 –1401 treatment goals, 1400 Ocular damage, 698 Ocular trauma, 1263 –1272 blow-out fracture clinical recognition, 1268 evidences, 1267 management, 1268 treatment goals, 1267 triage considerations, 1268 corneal and conjunctival injury, 1270 clinical recognition, 1270 evidences, 1270 fluorescein-staining corneal defect, 1270 management, 1270 treatment goals, 1270 triage considerations, 1270