title: Ocular hemorrhages in neonatal porcine eyes from single, rapid rotational events.
abstract: OBJECTIVE
  To characterize ocular hemorrhages from single, rapid head rotations in the neonatal pig.
  
  
  METHODS
  Three- to 5-day-old anesthetized piglets (n=51) underwent a single, rapid (117-266 rad/s) head rotation in the sagittal (n=13), coronal (n=7), or axial (n=31) planes. Six hours after injury, the animals were euthanatized and perfusion fixed, and the brain and eyes were harvested for gross and histopathologic examination by masked neuro- and ocular pathologists.
  
  
  RESULTS
  Ocular hemorrhage was found in 73% of animals (51% bilateral). Intraocular hemorrhage was primarily located near the vitreous base (70% of injured animals had ciliary body hemorrhage, and 11% had peripheral retinal hemorrhage). Hemorrhages were also found in the anterior chamber (11%), vitreous (5%), and optic nerve (disc, 8%; nerve sheath, 57%). Rapid axial head rotations resulted in a higher incidence of intraocular hemorrhage than coronal or sagittal head rotations, but the difference did not reach statistical significance (P=0.06). Control eyes had no injuries.
  
  
  CONCLUSIONS
  Optic nerve sheath and ciliary body hemorrhages were common in piglets that experienced a single, rapid head rotation. Retinal hemorrhage was present in a smaller number of animals. Most intraocular hemorrhages were located in regions of strong vitreous attachment, suggesting that this animal model will be useful in investigating the effect of vitreoretinal adhesion on ocular hemorrhage caused by inertial head rotations. Extrapolation of this model to the human infant should not be made until the effect of anatomic differences between the human and pig on the occurrence and patterns of ocular injuries is further investigated.
authors.affiliation: Department of Bioengineering, Scheie Eye Institute, University of Pennsylvania, and Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. bcoats@seas.upenn.edu
authors.forename: Brittany
authors.initials: B
authors.lastname: Coats
authors.forename: Gil
authors.initials: G
authors.lastname: Binenbaum
authors.forename: Robert L
authors.initials: RL
authors.lastname: Peiffer
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Forbes
authors.forename: Susan S
authors.initials: SS
authors.lastname: Margulies
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000867:Anterior Chamber / Q000293:injuries / Q000473:pathology; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000150:complications* / Q000473:pathology; D004195:Disease Models, Animal; D006257:Head; D020221:Optic Nerve Injuries / Q000473:pathology; D012160:Retina / Q000293:injuries* / Q000473:pathology*; D012166:Retinal Hemorrhage / Q000209:etiology* / Q000473:pathology*; D012399:Rotation; D013045:Species Specificity; D013552:Swine; D014822:Vitreous Body / Q000293:injuries / Q000473:pathology