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Exploring the Vitreoretinal Interface: A Key Instigator of Unique Retinal Hemorrhage Patterns in Pediatric Head
Helen H Song1, Wallace B Thoreson1, Pengfei Dong2
1Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Truhlsen Eye Institute, Omaha, NE, USA.
Insights
Infant shaking can cause retinal hemorrhages. Animal and computer models show shaking generates significant retinal stress, particularly during angular acceleration, potentially leading to vitreoretinal separation.
Area of Science:
- Ophthalmology
- Biomechanics
- Pediatric Trauma
Background:
- Retinal hemorrhages in children can result from various traumas, including accidental and nonaccidental head injuries.
- Understanding the biomechanical forces involved is crucial for diagnosing and preventing such injuries.
Purpose of the Study:
- To investigate the stress patterns in the eye during linear and angular accelerations.
- To simulate stresses during repetitive infant shaking and assess their potential to cause retinal damage.
Main Methods:
- Experiments were conducted on sheep and primate eyes to measure the tension stress required for retinal separation from the vitreous.
- A finite element model of a pediatric eye was developed to computationally measure tension stresses during simulated shaking.
Main Results:
- The tension stress for retinal separation in animal eyes ranged from 1 to 5 kPa.
- Computer simulations predicted shaking could generate 3 to 16 kPa of stress at the vitreoretinal interface.
- Angular acceleration produced higher, localized stress along retinal vasculature compared to linear acceleration's diffuse stress.
Conclusions:
- Simulated infant shaking can generate retinal tension stress exceeding the threshold for vitreoretinal separation.
- Angular acceleration is more likely to cause localized stress along retinal vasculature, while linear acceleration causes more diffuse stress.
Purpose:
Various types of trauma can cause retinal hemorrhages in children, including accidental and nonaccidental head trauma. We used animal eyes and a finite element model of the eye to examine stress patterns produced during purely linear and angular accelerations, along with stresses attained during simulated repetitive shaking of an infant.
Methods:
Using sheep and primate eyes, sclerotomy windows were created by removing the sclera, choroid, and retinal pigment epithelium to expose the retina. A nanofiber square was glued to a 5 mm2 area of retina. The square was pulled and separated from vitreous while force was measured. A finite element model of the pediatric eye was used to computationally measure tension stresses during shaking.
Results:
In both sheep and primate eyes, tension stress required for separation of retina from vitreous range from 1 to 5 kPa. Tension stress generated at the vitreoretinal interface predicted by the computer simulation ranged from 3 to 16 kPa during a cycle of shaking. Linear acceleration generated lower tension stress than angular acceleration. Angular acceleration generated maximal tension stress along the retinal vasculature. Linear acceleration produced more diffuse force distribution centered at the poster pole.
Conclusions:
The finite element model predicted that tension stress attained at the retina during forcible shaking of an eye can exceed the minimum threshold needed to produce vitreoretinal separation as measured in animal eyes. Furthermore, the results show that movements that involve significant angular acceleration produce strong stresses localized along the vasculature, whereas linear acceleration produces weaker, more diffuse stress centered towards the posterior pole of the eye.
