Common hypotheses for the biomechanical cause underlying neonatal retinal hemorrhage include elevated intracranial pressure (ICP) inducing venous outflow obstruction and retinal deformation. A finite element computational model of the eye, optic nerve, and orbit was simulated with particular attention to the retinal vessels to analyze stress and strain on these structures during external head compression associated with normal vaginal delivery. Pressure from maternal contractions displaced the eye backward into the orbit, and the stiff optic nerve sheath provided localized resistance to this posterior displacement at its insertion point, resulting in tensile strain of 2.5% in the peripapillary (central) retina. Correspondingly, retinal vessels experienced tensile stress of up to 2.3 kPa near the optic nerve insertion point and opposing compressive stress of up to 3.2 kPa further away. The optic nerve was longitudinally compressed and experienced a mean radial tensile strain of 2.0%. Overall, forces associated with maternal labor resulted in a pattern of eye deformation that stretched the central retina in this simulation, mirroring the classical posterior localization of neonatal retinal hemorrhage. The optic nerve increased modestly in diameter despite rising ICP, suggesting retinal deformation is a more likely mechanism for retinal hemorrhage than occlusion of the central retinal vein.

PURPOSE: With the growing popularity of badminton worldwide, the incidence of badminton-related ocular injuries is expected to rise. The high velocity of shuttlecocks renders ocular traumas particularly devastating, especially with the possibility of permanent vision loss. This study investigated the mechanism behind ocular complications through simulation analyses of mechanical stresses and pressures upon shuttlecock impact. DESIGN: Computational simulation study. PARTICIPANTS: None. METHODS: A 3-dimensional human eye model was reconstructed based on the physiological and biomechanical properties of various ocular tissues. Finite element analysis simulations involved a frontal collision with a shuttlecock projectile at 128.7 km/hour (80 mph). Intraocular pressure (IOP) changes and tissue stress were mapped and quantified in the following ocular structures: the limbus, ciliary body, zonular fibers, ora serrata, retina, and optic nerve head. MAIN OUTCOME MEASURES: Intraocular pressure and tissue stress. RESULTS: Upon shuttlecock impact, compressive force was transferred to the anterior pole of the cornea, propagating posteriorly to the optic nerve head. Deflection of forces anteriorly contributed to refractory oscillations of compressive and tensile stress of ocular tissue. Initial impact led to a momentary (<1 ms) spike in IOP 5.66 MPa (42.5 × 103 mmHg) that radially distributed for a very brief instance (<1 ms) of pressure at the trabecular meshwork of the iridocorneal angle of 1.25 MPa (9.4 × 103 mmHg). The lens had a maximal posterior displacement of 1.5 mm with peak zonular fiber tensile strain of 52%. The limbus, ciliary body, and ora serrata had a peak tensile stress of 5.16 MPa, 1.90 MPa, and 0.62 MPa, respectively. Compressive force from the sclera concentrated at the optic nerve head for a peak stress of 5.97 MPa while peak pressure from vitreous humor was 7.99 MPa. CONCLUSIONS: Shuttlecock impact led to a very brief, substantial rise in pressure and stress significant for tissue damage and subsequent complications, such as secondary glaucoma, angle recession, lens subluxation, hyphema, or retinal dialysis. Our findings offer valuable mechanistic insights into how ocular structures are affected by shuttlecock projectile impact to inform clinical assessments and treatment strategies, while highlighting the importance of protective eyewear in racket sports. FINANCIAL DISCLOSURES: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.