contact lens case reports

Treating Serious Ocular Injuries

BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDR�, FCLSA
July 1999

In most cases, ocular chemical injuries are relatively minor and can easily be treated by irrigation. In other cases, a splash of an alkaline or acidic solution into an eye causes an immediate change in pH, often resulting in severe damage to the external ocular tissues. Alkali injuries generally are more damaging to the eye than those caused by acids. On the ocular surface, alkalis destroy cell membranes and denature collagen. This weakened state facilitates the alkalis' rapid penetration into the deeper layers of the cornea as well as into the aqueous and vitreous. The severity of an alkaline injury depends upon the anion concentration, the duration of exposure and the pH of the solution. (Significant injuries occur at a pH of 11.0 or higher).

Case History

M.M. is a 32-year-old male who suffered an alkali injury OU in 1985. He has since undergone an extra capsular cataract extraction and an intraocular (IOL) implant OU, as well as three corneal transplants OD and four OS. Additionally, he had bilateral tube shunts implanted for management of his IOP.

The corneal transplant OD has been stable since 1994, with an uncorrected visual acuity of 20/400, but he continues to suffer from recurrent epithelial defects and uncontrolled IOPs in his left eye. Since that time, the left transplant has been free of epithelial defects, with a visual acuity of hand motion, and an IOP of 40 mm Hg (Fig. 1).

FIG. 1: Patient's left eye following four graft failures.

FIG. 2: Photokeratoscopy of the patient's right eye (note the significant irregular astigmatism).

FIG. 3: Patient's right eye with the aspheric RGP lens.

Slit lamp exam revealed an intact but irregular corneal surface (Fig. 2). There were 360š of host neovascularization extending to the graft-host interface, except at the 3 o'clock position, where a mild pannus was present. Minor punctate staining and slight stromal haze were present in the central cornea.

A Successful Fit

M.M. was diagnostically fit with the AS-2OH aspheric RGP lens (Contex). The final lens parameters were 6.90 -8.00 9.2, with a visual acuity of 20/30 (Fig. 3). He continues to be successful with the contact lens on a regimen of preservative-free artificial tears every hour, Cell-U-Visc (Allergan) at night and a maximum wearing time of 12 hours per day. He is being routinely followed every 3 months for signs of graft rejection and we are continuing to monitor his IOPs.

Corneal transplantation following a severe chemical injury may be a patient's only option for visual rehabilitation. In cases of alkali burns, multiple graft rejections are often the rule, rather than the exception. Correcting with contact lenses must be approached with caution in order to limit mechanical and physiologic trauma to the delicate graft.

Patrick Caroline is an associate professor of optometry at Pacific University and an assistant professor of ophthalmology at the Oregon Health Sciences University.

Mark Andr� is director of contact lens services at the Oregon Health Sciences University.