EyeWorld Asia-Pacific September 2016 Issue

EWAP CORNEA 63 September 2016 Views from Asia-Pacific LIM Li, MD Senior Consultant and Head (Clinical and Education), Corneal and External Eye Disease Service, Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 U ses of Mitomycin C in Corneal Surgery Mitomycin C is an alkylating agent with cytotoxic and antiproliferative effects. It has long been used in glaucoma surgery to prevent scarring and resultant bleb failure. In corneal surgery, mitomycin C has been used in pterygium surgery, in the treatment of corneal intraepithelial neoplasia, and in excimer laser surface ablations. By reducing the risk of postoperative corneal haze in excimer laser surface ablation techniques such as PRK, LASEK, and epiLASIK, mitomycin C has played an important role in the current revival of these procedures. It is usually applied at a concentration of 0.2 mg/ml (0.02%) for about 20 to 60 seconds over the ablated stroma. For low to moderate myopia, some studies show that lower concentrations (0.01%, 0.002%) could also be effective in preventing haze. The concern on the use of mitomycin C at this dosage is its effect on the corneal endothelium. However, most studies show that the corneal endothelium is not affected. Mitomycin-C (commonest concentration 0.02%) has also been used to reduce the recurrence of pterygium in the bare sclera excision technique of pterygium surgery. This could be in the form of an intraoperative application (0.02%) for 2–3 minutes or as postoperative eyedrops (0.02%) 4 times a day for a week duration. However, the use of mitomycin C is associated with vision-threatening complications, including scleral thinning, ulceration, and delayed conjunctival epithelialization. Hence, conjunctival autografting or aminiotic membrane transplant is to be preferred in pterygium surgery and the use of mitomycin C should be avoided. A few years ago, an eye-whitening procedure was developed in Korea1 as a cosmetic procedure for conjunctival hyperemia. This involved medial and lateral wide conjunctival excisions with removal of tenon capsule. Postoperatively, MMC 0.02% was used 4 times daily for 2 to 5 days. In an independent review,2 the complication rate was found to be high including serious complications such as scleral thinning and calcific plaques. This procedure has subsequently been discontinued in Korea. Be on the lookout for patients who have had eye-whitening procedures performed as the complications could develop years after the procedure. I recently performed bilateral scleral patch grafts for bilateral scleral melt/calcific plaque formation for a 43-year-old Chinese female who had a bilateral eye- whitening procedure performed in China 3 years ago (figures 1–4). References 1. Kim BH. Regional conjunctivectomy with postoperative Mitomycin C to treat chronic hyperemic Conjunctiva. Cornea . 2012;31:236–244 2. Lee S, Go J et al. Cosmetic Regional Conjunctivectomy with Postoperative Mitomycin C Application With or Without Bevacizumab Injection. Am J Ophthalmol. 2013;156:616–622. Editors’ note: Dr. Lim declared no relevant financial interests. Figure 1. Right nasal scleral melt with calcific plaque Figure 3. Left temporal scleral melt Figure 2. Right scleral patch graft Figure 4. Left temporal scleral patch graft continued on page 64