Eye Injury Risk from Water Stream Impact Essay

Ocular injuries caused by solid projectiles have been described in the literature (Duma, 2005; Kennedy, 2006; Kennedy, 2007). However, the impact of a high-velocity water stream on the globe has not been previously quantified. Such pressurized water jets can be found in children’s water toys, squirt guns, and interactive water fountains. As the velocity of these water streams increases, product capabilities, and therefore popularity, likewise increase. In addition to those on the market, water gun enthusiasts custom build powerful guns in order to maximize flow rate, often in excess of 55 ft/s. Interactive water fountains (also called wet decks, splash pads, spray pads, or spray parks) are found in public areas and water parks throughout the country. The attractions feature synchronized jets of water, typically directed vertically from nozzles in the ground. While playing, it is possible for a child to look into the nozzle in anticipation of the next spurt of water which could in theory cause an eye injury. However, the increasing popularity of these fountains has not been matched by appropriate regulation. The CDC recommends that health departments update pool codes to include interactive water features that do not have standing water (Prevention, 2007) due to a series of outbreaks of gastroenteritis (Minshew, 2000). The lack of research and injury assessment has delayed the process, as most states have not established codes. Current available legislation is listed in Table 1. The primary focus of concern in current legislation is centered on the filtration system and prevention of spread of bacterial infection. This concern has taken attention away from the potential for mechanical injury due to a high-velocity water jet directed toward a child’s eyes, ear, or mouth. This study consisted of five parts: Part I includes previous research and case studies that have been reviewed to begin to understand the need for water eye injury research and the previous efforts made to investigate this injury mechanism. In Part II, a range of objects and devices were analyzed to determine water characteristics and the associated injuries. A summary table of the results was produced. In Part III, projectile impact tests were performed with three different projectiles and a range of velocities to measure normalized energy and internal pressure within the eye. For Part IV, water jet impacts were performed with three nozzle diameters and a range of water velocities to measure internal eye pressure to assess injury. In Part V, data from Part III were used to determine a correlation between normalized energy and internal eye pressure to then calculate normalized energy for the measured internal eye pressure during the water jet impacts (Part IV). Previously developed injury risk curves for corneal abrasion, hyphema, lens dislocation, retinal damage and globe rupture were applied to the calculated normalized energy to determine injury risk for the water jet impacts. Nozzle type, size, and maximum velocity are a critical part of an interactive water fountain’s performance, but until relationships between these factors and injury have been established, it is hard to place numerical guidelines on their design. This report aims to quantify the incidence and mechanics of water-induced eye injuries and benchmark the fluid mechanics of current water systems and toys. Documented cases of high-velocity water-induced eye injuries confirm the potential danger of these water blasts (Table 2). Many of the reported incidents occurred in the workplace and involve pressure washers, agricultural irrigation sprinklers, or fire hoses. While studies of water-induced eye injuries on humans have not been conducted, animal studies have linked high-velocity water jets to eye damage. Fish (Oncorhynchus tshawytscha) exposed to submerged water jets at velocities ranging from 40 to 65 ft/s were examined for injury. Nearly half of all fish suffered eye injuries (bulged, hemorrhaged, or missing) at velocities of 55 ft/s and above (Deng, 2005). In a similar study, fish were released at velocities from 0 to 70 ft/s and the authors found velocity to be positively correlated to severity of injury (Nietzel, 2000). Minor severity was noted when there was a visible injury that had no threat to life and major severity was noted when the injury was a threat to life and persisted throughout time.