Potential Toxicity of Mitomycin C

CW, Huang HT, Bair JS, Lee CC. Trabeculectomy with simultatopical application of mitomycin-C in refractory glaucoma. J Ocul Phar-

1. Chen neous

To the Editor. \p=m-\Chenet al1 and Palmer2 recently reported on the use of mitomycin C as adjunct chemotherapy during glaucoma filtration surgery. Both investigations followed similar protocols in which the episclera was soaked with a solution of 0.2 to 0.4 mg/mL of mitomycin C for 5 minutes before creating a sclerostomy. The authors concluded that a single, intraoperative application of mitomycin C favorably affected the outcome of trabeculectomy surgery. Although their studies have no concurrent control groups, two randomized controlled trials comparing fluorouracil with topical mitoSee also pp 1693 and 1725.

mycin are underway (Association for Research in Vision and Ophthalmology, 1991). No intraocular toxicity was reported using this protocol. Although retinal toxicity has been demonstrated after intravitreal injection of mitomycin C in the rabbit model,3 no studies have addressed intraocular toxicity following injection into the anterior chamber. We studied the intraocular toxicity of mitomycin C following intracameral injection because of the demonstrated potency of this medication, and the anticipated use of mitomycin C in glaucoma surgery. Materials and Methods. —Our study design was approved by The Johns Hopkins University (Baltimore, Md) Committee on the Use and Care of Animals. Four New Zealand white rabbits were anesthe¬ tized with intramuscular injections of ketamine hydrochloride (35 to 45 mg/kg) and xylazine hydrochloride (5 to 10 mg/kg). Intracameral injections of 50 µ]., of mitomycin C (0.5 mg/mL of balanced salt solution) were made through a corneal paracentesis in four eyes, and an identical volume of balanced salt solution was similarly injected into the anterior chamber of the contralateral eye to serve as a control. All four eyes injected with mitomycin C demonstrated a severe inflammatory response within 24 hours. Within 72 hours, the four corneas exposed to mitomycin C were opaque and markedly thickened. Although one edematous cornea spontaneously cleared within 10 days after injection, the remaining three eyes showed progressive, irreversible bullous keratopathy. Histopathologic study performed 2 weeks after injection revealed corneal edema with complete absence of normal corneal endothelium, engorgement of iris blood vessels with necrosis of the iris and ciliary body, and acute inflammatory cells in the anterior chamber. The retina appeared normal on clinical and histologie examinations. No toxicity was seen in the control eyes.

Comment.— Mitomycin C demonstrates severe toxicity when one drop of the recommended topical dose is placed directly in the anterior chamber. Such severe effects might occur if mitomycin C was applied after creating the scleros¬ tomy, or if it was injected subconjunctivally during the post¬ operative period. Those surgeons who use mitomycin C rec¬ ommend irrigation of the episclera after its application. This appears wise if the toxicity indicated in experimental rabbits is likely to occur in humans. Robert J. Derick, MD Louis Pasquale, MD Harry A. Quigley, MD Henry Jampel, MD Baltimore, Md

macol. 1990;6:175-182. 2. Palmer SS. Mitomycin

as

adjunct chemotherapy

with

Ophthalmology. 1991;98:317-321.

trabeculectomy.

3. Peyman GA, Greenberg D, Fishman GA, Fiscella R, Thomas A. Evaluation of toxicity of intravitreal antineoplastic drugs. Ophthalmic Surg.

1984;15:411-413.

Hyphema Caused by Air Bag To the Editor.\p=m-\Rimmer and Shuler1 recently reported the first case of severe ocular trauma occurring in a patient who was "protected by a driver's-side air bag." I describe herein a patient who, rather than being protected by the air bag, suffered an ocular injury directly attributable to the air bag.

Report of a Case.\p=m-\A 34-year-old woman driving between 40 and 65 km/h skidded into another car on wet pavement. She was wearing a three-point lap-shoulder seat belt when the air bag inflated. The car sustained damage to the front end, but the passenger compartment and windows were intact. The patient presented to the emergency department with abrasions and contusions primarily centered in the middle of her face. Her unaided visual acuity was 20/200 OD and hand movement in the left eye. Abrasions were present on both eyelids, slightly greater on the left than on the right. She had corneal epithelial abrasions over the superior half of both corneas, associated with stromal thickening and striae of Descemet's membrane. The right eye had 1 + anterior chamber cellular reaction; the left eye had a 20% hyphema and an irregular unreactive pupil. She was hospitalized, treated with bed rest and binocular patching, and bled again before being discharged. A small retinal hemorrhage was thereupon noted, but no retinal tears were found. A small angle recession was also noted on gonioscopy. Sixteen days after the injury, her pinhole vision was 20/30 +2 OU. Intraocular pressures were never elevated, and her vision improvement coincided with resolution of the hyphema in the left eye and of the corneal abrasions and corneal edema. Comment. —In the case described by Rimmer and Shuler, there was a question of whether the eye injury was due directly to the air bag or to the air bag forcing the patient's head against the driver's side window. The case I have de¬ scribed, with the bilateral eye injuries and central symmetri¬ cal facial abrasions, implicates the air bag as the cause of the ocular injuries. In addition, given the state of the undamaged passenger compartment, speculation may arise as to whether this patient may have avoided serious ocular damage had the air bag not inflated. Given its recent introduction to the mass market, there is no doubt that more ocular injuries attributed to air bags will be noted. Perhaps further refinements of the air bags will allow them to keep their well-established attri¬ butes while eliminating their potential for causing ocular

injuries.

Ken E.

Mishler, MD

Pompton Lakes, NJ 1. Rimmer S, Shuler J. Severe ocular trauma from Arch Ophthalmol. 1991;109:774.

a

driver's-side air

bag.

The Lens Opacities Case-Control Study

To the Editor. \p=m-\Weread with interest the article by Leske et

al1 in the February 1991 issue of the Archives. The authors identified ingestion of gout medications as a risk factor for the

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Potential toxicity of mitomycin C.

Potential Toxicity of Mitomycin C CW, Huang HT, Bair JS, Lee CC. Trabeculectomy with simultatopical application of mitomycin-C in refractory glaucoma...
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