Eyeglass wear presents an additional risk factor for ocular injury during airbag inflation. Frame damage and lens shatter provide potential for both blunt and penetrating types of ocular injury.
Previous studies have demonstrated that in glia and astrocytes Mn(II) is distributed with ca. 30-40% in the cytoplasm, 60-70% in mitochondria. Ca(II) ions were observed to alter both the flux rates and distribution of Mn(II) ions in primary cultures of chick glia and rat astrocytes. External (influxing) Ca(II) ions had the greatest effect on Mn(II) uptake and efflux, compared to internal (effluxing) or internal-external equilibrated Ca(II) ions. External (influxing) Ca(II) ions inhibited the net rate and extent of Mn(II) uptake but enhanced Mn(II) efflux from mitochondria. These observations differ from Ca(II)-Mn(II) effects previously reported with "brain" (neuronal) mitochondria. Overall, increased cytoplasmic Ca(II) acts to block Mn(II) uptake and enhance Mn(II) release by mitochondria, which serve to increase the cytoplasmic concentration of free Mn(II). A hypothesis is presented involving external L-glutamate acting through membrane receptors to mobilize cell Ca(II), which in turn causes mitochondrial Mn(II) to be released. Because the concentration of free cytoplasmic Mn(II) is poised near the Kd for Mn(II) with glutamine synthetase, a slight increase in cytoplasmic Mn(II) will directly enhance the activity of glutamine synthetase, which catalyzes removal of neurotoxic glutamate and ammonia.
* BACKGROUND AND OBJECTIVES: The effectiveness of air bags as a safety device in decreasing fatalities and reducing morbidity in frontal impact motor vehicle accidents has been well established. However, case reports have surfaced documenting ocular injuries related to air bag inflation. The purpose of this study was to identify and analyze ocular injuries sustained during air bag inflation.
* PATIENTS AND METHODS: Hospital emergency room records were reviewed retrospectively for a period of 4 years for patients who had sustained ocular injuries in motor vehicle accidents. Those injuries associated with air bag inflation were analyzed as to the nature of the injury, type of vehicle, speed, and visual morbidity.
* RESULTS: Fourteen cases of ocular injury related to air bag inflation were identified. Hyphema (nine cases) and cornea abrasion (eight cases) were the most common. Three cases, all patients who had been wearing glasses, sustained serious and permanent ocular damage.
* CONCLUSION: While air bags are an unequivocal safety feature, ocular injuries do occur that are related to air bag inflation. Eyeglass wear may present an additional risk factor.
[Ophthalmic Surg Lasers 1995;26:542-548.]
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