Impact resistance of common spectacle and safety lenses to airgun and rimfire projectiles

Paul J. Rychwalski, Eric A. Packwood, Oscar A. Cruz, John B. Holds

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Purpose: To evaluate the penetration resistance of common spectacle and safety lenses to high-velocity projectiles and to examine the current recommendations regarding the use of such lenses. Methods: The penetration threshold of glass, high-index, and polycarbonate spectacle and safety lenses was determined by firing BBs, pellets, and 0.22-caliber projectiles. The mass, diameter, velocity, and energy of each projectile were measured, and the center thickness, mass, and refractive power of each lens were recorded. The penetration threshold for each lens type was calculated, and a comparison of impact resistance was made. Results: The maximum velocity of the BB was measured at 221 m/s; pellets at 210 m/s; CB.22 rimfire projectiles at 204 m/s; and 0.22 rimfire projectiles at 290 m/s. The BB penetration thresholds were as follows: glass lenses = 84.0 m/s (2.4 J) and high-index lenses = 107.7 m/s (4.09 J). Polycarbonate spectacle and safety lenses were not penetrated by BBs regardless of their velocity; however, these lenses were penetrated by CB.22 rimfire projectiles (89.2 J). Review of the penetrated lenses showed that center thickness and refractive power was comparable between the various groups of projectiles. Conclusions: Polycarbonate offers a vastly superior degree of penetration resistance compared with other commonly used lens materials. The current recommendations regarding the use of polycarbonate in prescription and protective lenses, as endorsed by the American Academy of Ophthalmology and the American Academy of Pediatrics, must be reevaluated.

Original languageEnglish (US)
Pages (from-to)268-273
Number of pages6
JournalJournal of AAPOS
Volume7
Issue number4
DOIs
StatePublished - Aug 2003
Externally publishedYes

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Ophthalmology

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