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Complications have ranged from hyphema,2 posterior capsular rupture,2–3,6 vitreous hemorrhage,3 retinal detach-ment,6 macular contusion,2 and corneal perforation.5

Luer-lock adaptors were developed to prevent inadvertent cannula release. In this case the viscoelastic used had a luer-lock adaptor, but it was the adaptor that separated from the syringe and projected, with the attached cannula, into the anterior chamber, disrupting the posterior capsule. This case was reported to the manufacturer, and the syringe and cannula were submitted for investigation. After review no equipment malfunction was noted. The US Food and Drug Administration has 6 reports of the luer-lock adaptor and cannula becoming detached from the syringe of the same viscoelastic, and in several cases this resulted in puncturing of the posterior capsule, requiring a vitrectomy.7 This is the first Canadian report of a similar complication.

To our knowledge this is the second report of release of a viscoelastic cannula during cataract surgery. In the case of Prenner et al.6 no mention was made of the viscoelastic can-nula design. Although a luer lock, as present in our case, should decrease the chance of detachment, it is possible that the luer-lock connection weakened with the force used to attach the cannula or as a result of pressure when the visco-elastic was injected through the cannula. Other viscoelastics

have a cannula-locking ring that is secured over the cannula, decreasing the possibility of detachment. This case high-lights the importance of checking the design of the visco-elastic cannula connection; for those lacking a locking ring, the surgeon should carefully check the cannula prior to use.

REFERENCES

1. Munshi V, Sampat V, Pagliarini S. Zonular dialysis and vitreous loss with a J-shaped hydrodissection cannula during phacoe-mulsification. J Cataract Refract Surg 2005;31:450–1.

2. Rumelt S, Kassif Y, Koropov M, et al. The spectrum of iatrogenic intraocular injuries caused by inadvertent cannula release during anterior segment surgery. Arch Ophthalmol 2007;125:889–92.

3. Dinakaran S, Kayarkar VV. Intraoperative ocular damage caused by a cannula. J Cataract Refract Surg 1999;25:720–1.

4. Bradshaw SE, Shankar P, Maini R, Ragheb S. Ocular trauma caused by a loose sliplock cannula during corneal hydration. Eye 2006;20:1432–4.

5. Wiggins MN, Uwaydat SH. Cannula ejection into the cor-nea during wound hydration – video report. Br J Ophthalmol 2008;92:181.

6. Prenner JL, Tolentino MJ, Maguire AM. Traumatic retinal break from viscoelastic cannula during cataract surgery. Arch Ophthal-mol 2003;212:128–9.

7. US Food and Drug Administration. Maude database. Avail-able at: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cf-MAUDE/search.CFM.

Y.M. Buys,* M. Firat,† M.H. Brent**University of Toronto, Toronto Western Hospital, and

†Medical Engineering, University Health Network, Toronto, Ont.

Correspondence to Y.M. Buys, MD: y.buys@utoronto.ca

Can J Ophthalmol 2009;44:102–3doi:10.3129/i08-157

Fig. 1—Cannula attached to luer lock and de-tached from viscoelastic syringe.

Recurrent Meesmann’s corneal dystrophy: treatment with keratectomy and mitomycin C

A 35-year-old Caucasian man was first seen for an un-usual punctate keratitis with symptoms of foreign

body sensation and photophobia OD for several months. There was no significant ocular history. Best-corrected Snellen visual acuity (BCVA) was 20/40 OD and 20/30 OS. Intraepithelial microcysts and mild punctate epithelial erosions were noted in both corneas, with increased con-centration in the interpalpebral fissure area. The remainder of the ocular examination was unremarkable. Meesmann’s corneal dystrophy was diagnosed but with relatively good visual acuity; only the conservative measure of artificial tear use was offered.

At a 3-month follow-up, visual symptoms had worsened (Fig. 1), and BCVA had decreased to 20/70 OD. Photo-

therapeutic keratectomy (PTK) with the VISX STAR Ex-cimer Laser (Advanced Medical Optics, Santa Ana, Calif.) was performed. The epithelium was removed manually before the laser treatment. The excimer laser was set for a 4 mm circular ablation zone where the lesions were most concentrated and at a treatment depth of 10 μm. There was no surgical complication. Fluorometholone and ofloxacin were used topically postoperatively, yet recurrence was al-ready noted 2 weeks posttreatment. The patient’s BCVA deteriorated to 20/200 OD with central corneal haze. A manual keratectomy was done, removing the epithelium and subepithelial fibrosis, and resulted in a smooth, clear central cornea. BCVA improved to 20/50 OD with symp-tomatic relief 1 month postoperative. A subsequent similar manual keratectomy was performed in the left eye because BCVA had reduced to 20/60 OS. Again, fluorometholone and ofloxacin were used topically postoperatively.

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Recurrence was again seen bilaterally within 2 months. The patient’s condition worsened; OD BCVA was count-ing fingers at 1.2 m. However, the left eye responded well, with BCVA at 20/40. To treat the right eye, a third kera-tectomy was carried out manually, again removing epithel-ium and subepithelial fibrotic tissue, with adjuvant topical mitomycin C (MMC) therapy. The area treated was again the central 4 mm. Care was taken to avoid the limbal stem cells. MMC at 0.3 mg/mL was placed over the cornea with Weck-cel sponge (Medtronic ENT, Jacksonville, Fla.) for 90 seconds after epithelial debridement. A higher concen-tration than is typical after excimer laser use was chosen because of the recurrent nature of the condition. The cor-nea was then irrigated copiously with saline. Two weeks postoperative, the patient had a BCVA of 20/50. The epi-thelial cystic lesions and punctate erosions were reduced sig-nificantly. At the 3-year follow-up, Meesmann’s dystrophy remained stable with BCVA of 20/30 OD (Fig. 2) but had slowly worsened in the left eye, which has not yet been treated with MMC, to a BCVA of 20/70.

Recurrence of a superficial dystrophy after PTK treat-ment is observed frequently.1 The next accepted method of treating recurrent, severe forms of Meesmann’s dystrophy is penetrating keratoplasty; however, recurrence has also been reported to occur.2 We hereby report a novel attempt of treating severe, recurrent Meesmann’s corneal dystrophy with topical MMC. MMC modulating the corneal re-sponse to injury and treatment of corneal dystrophies had

previously been noted in the literature.3 MMC is a potent DNA cross-linker. It has been suggested that MMC may work by preventing proliferation of stromal keratocytes or epithelial cells in the treatment of anterior corneal dystro-phies.4–5 The exact mechanism of action of MMC on anter-ior dystrophies such as Meesmann’s is not known but it may reduce epithelial or epithelial–stromal interaction of pro-duction of keratin proteins felt to be involved in the clinical manifestations of this disorder.6 Although MMC is known to inhibit fibroblasts, it is also used in epithelial tumors, such as breast7 and esophageal8 tumors, suggesting there are almost certainly effects on epithelial tissue as well. The use of topical MMC in conjunction with keratectomy may pre-vent the recurrence or mediate stabilization of Meesmann’s corneal dystrophy. The duration of effect, exact optimal dosage, and concentration of MMC is as yet unknown.

REFERENCES

1. Fagerholm P. Phototherapeutic keratectomy: 12 years of experi-ence. Acta Ophthalmol Scand 2003;81:19–32.

2. Cogan DG, Kuwbabara T, Donaldson D, Collins E. Microcyst-ic dystrophy of the cornea. A partial explanation for its patho-genesis. Arch Ophthalmol 1974;92:470–4.

3. Lee ES, Kim EK. Surgical do’s and don’ts of corneal dystrophies. Curr Opin Ophthalmol 2003;14:186–91.

4. Marcon AS, Rapuano CJ. Excimer laser phototherapeutic kera-tectomy retreatment of anterior basement membrane dystrophy and Salzmann’s nodular degeneration with topical mitomycin C. Cornea 2002;21:828–30.

5. Ayres BD, Hammersmith KM, Laibson PR, Rapuano CJ. Phototherapeutic keratectomy with intraoperative mitomycin C to prevent recurrent anterior corneal pathology. Am J Oph-thalmol 2006;142:490–2.

6. Nishida K, Honma Y, Dota A, et al. Isolation and chromosomal localization of a cornea-specific human keratin 12 gene and de-tection of four mutations in Meesmann corneal epithelial dys-trophy. Am J Hum Genet 1997;61:1268–75.

7. Massacesi C, La Cesa A, Marcucci F, et al. Capecitabine and mitomycin C is an effective combination for anthracy-cline- and taxane-resistant metastatic breast cancer. Oncology 2006;70:294–300.

8. Darnton SJ, Archer VR, Stocken DD, Mulholland PJ, Casson AG, Ferry DR. Preoperative mitomycin, ifosfamide, and cisplatin followed by esophagectomy in squamous cell car-cinoma of the esophagus: pathologic complete response induced by chemotherapy leads to long-term survival. J Clin Oncol 2003;21:4009–15.

Jacky Y.T. Yeung,* William G. Hodge†

*University of Toronto, Toronto, Ont., and †University of Western Ontario, London, Ont.

Correspondence to William G. Hodge, MD: william.hodge@sjhc.london.on.ca

Can J Ophthalmol 2009;44:103–4doi:10.3129/i08-179

Fig. 1—Meesmann’s corneal dystrophy OD just before first surgical treatment.

Fig. 2—Meesmann’s corneal dystrophy OD, 3 years post–manual keratectomy with topical mitomycin C adjuvant therapy.