contact lens case reports
It's All Fun and Games with Eye-Protecting RGP Lenses
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
JC is a 35-year-old female patient with a 12-year history of successful RGP lens wear. Her present lens specifications are OD: 41.50 2.25 9.5, OS: 41.75 1.75 9.5 with VAs of 20/20 OU. Her habitual wearing time is 14 to 16 hours a day.
On November 14, 1999, a 3.0mm piece of a large metal staple that the patient had been removing from a box broke and struck her left eye. The projectile hit her left RGP lens, breaking it into four pieces (Figure 1). The patient removed three of the pieces immediately following the injury; the fourth was retrieved from the upper fornix at the time of her examination.
Figure 1. JC's fractured RGP lens
Slit lamp examination revealed two small epithelial defects in the lower third of the cornea surrounded by diffuse epithelial edema (Figure 2). There appeared to be no corneal involvement below the epithelium. The anterior chamber OS had 1+ cells, and the pupil responses were normal. Visual acuity with glasses was OD 20/20, OS 20/40. The patient was treated with appropriate antibiotics and asked to return the next day for follow-up.
Figure 2. Epithelial defects secondary to the lens fracture
The next day her visual acuity with glasses was OD 20/20, OS 20/25. The epithelial defects were 95 percent healed, with only slight corneal edema remaining around the site of the injury. Ophthalmoscopy of the right eye was within normal limits. The left eye, however, revealed a posterior vitreous detachment, most likely related to the previous day's trauma. Subsequent follow-ups showed the cornea completely healed with no residual scarring. The patient's lens was replaced, and she eventually resumed her habitual wearing schedule.
Contact Lenses and Corneal Trauma
Traumatic fracture of a rigid contact lens is a rare event. In this case, the patient's rigid gas permeable lens may have served an important role in protecting her cornea from a severe penetrating injury. The presence of an RGP lens can both slow down the velocity of an airborne projectile, and distribute the projectile's force over a significantly larger area before the contact lens breaks into multiple pieces.
It is therefore not surprising that ophthalmic literature cites numerous examples in which patients' eyes were protected while wearing rigid contact lenses. In a 1975 report, Rengstorff and Black cited 125 cases in which the presence of contact lenses protected the eyes. Their series reported no cases in which an eye was seriously injured by a contact lens when hit by a projectile.
Although wearing rigid contact lenses may help protect the eyes from potentially harmful projectiles, be sure to caution patients that contact lenses are not a substitute for safety eyewear.
Patrick Caroline is an associate professor of optometry at Pacific University and an assistant professor of ophthalmology at the Oregon Health Sciences University.
Mark André is director of contact lens services at the Oregon Health Sciences University.