EyeWorld Asia-Pacific September 2016 Issue

September 2016 64 EWAP cornea Views from Asia-Pacific Vilavun PUANGSRICHARERN, MD Chief of Cornea Service, King Chulalongkorn Memorial Hospitals Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University Rama IV Road, Pathumwan, Bangkok 10330, Thailand Tel. no. +66-22564424 Fax no. +66-22528290 vilavun@hotmail.com M itomycin 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. Mitomycin-C is an antineoplastic agent. It has an irreversible effect on inhibiting cell replication. Due to its action on suppressing fibrolastic activity, I use MMC in three main indications: 1. Pterygium surgery 2. Ocular surface Neoplasia 3. Ocular surface reconstruction 1. Pterygium surgery MMC is very effective in cases with higher risk for recurrence; younger age (<40 years), multiple recurrent pterygium (more than two recurrences), large and fleshy pterygium, and patients whose activity is mostly exposed to UV—but not in simple cases. Technique: Intraoperative single application After massive subconjunctival tissue has been removed, the sclera is covered with a plastic sheet to avoid direct contact of the drug to the bare sclera. Small pieces of sponge, soaked with MMC at the concentration of 0.02% are placed beneath the conjunctival edge with exposure to the remaining subconjunctival tissue. The sponges are left for 3 minutes and discarded with care. The subconjunctival space is washed thoroughly with a large amount of BSS before conjunctival or amniotic membrane graft is performed. Complications Complications are devastating. These are scleral melts and necrosis, scleral plaque, infectious scleritis (mostly caused by Pseudomonas spp.), and infectious endophthalmitis in extreme cases. Tips for preventing these complications • Always protect the bare sclera from direct exposure to the drug (using a plastic sheet). Apply MMC directly to the subconjunctival tissue without touching it. • Squeeze out the excessive MMC solution from the sponges to avoid spillage. • Check the concentration and exposure time. • Wash tissue thoroughly after the application. • Never use as topical drop postoperatively. 2. Ocular surface neoplasia Indications are 1) massive involvement of tumor on the ocular surface when surgi- cal resection is not applicable and 2) as adjunctive therapy after complete tumor resection (with or without free margin of tumor). Technique and how to avoid complications • Topical application of 0.02% MMC, 3 times a day for 1 week, followed by 1 week free for at least 3 cycles • The concentration can be increased to 0.04% MMC • Always prescribe preservative-free artificial tears during the course • Ocular surface toxicities such as punctate keratitis, epithelial defects should be observed especially in older patients 3. Ocular surface reconstruction (OSR) Intraoperative single application of 0.02–0.04% MMC can be used in cases of OSR when there are increasing chance of inflammation and fibrosis. Examples are cases of Stevens–Johnson syndrome, chronic chemical injuries, or a variety of limbal stem cell deficiencies Editors’ note: Dr. Vilavun declared no relevant financial interests. Johan HUTAURUK, MD Director, Jakarta Eye Center Jl. Terusan Arjuna Utara No. 1, Kedoya, Daerah Khusus, Ibukota Jakarta 11520, Indonesia Tel. no. +62-21-2922-1000 johan.hutauruk@cbn.net.id H aving seen the devastating complications of scleral melting after pterygium surgery using mitomycin-C (MMC), I never use MMC for primary pterygium. The use of MMC in my opinion should be limited to recurrent pterygium, and only on eyes which have at least two recurrences, so for the third surgery I will consider using MMC. Necrotizing scleritis which can lead to scleral perforation is a potentially blinding condition which is the most difficult complications of MMC to manage. Pterygium is usually easy to remove with a very low risk of blindness even with the recur- rence problem. We should be very cautious of using topical MMC for recurrent pterygium as a single intraoperative use of MMC is safer than postoperative daily application. Prevention of corneal haze The use of MMC in my practice is a routine for every patient with corneal surface ablation with PRK or PTK. Haze formation with loss of transparency and surface irregularities will certainly decreased the visual acuity, and there are many articles reported the risk of haze formation after corneal refractive surface surgery. Last year in 2015, the total LASIK procedures in our center were 3,848 eyes, but the number of cases with surface ablation were only 11 eyes. The most com- mon indication for surface ablation in our center is for the retreatment after LASIK complications (decentered ablation, flaps irregularities, etc.) and since the residual corneal thickness is not enough to smoothen the corneal surface, PRK is certainly a good option to fix this condition using the topography-guided program of LASIK machines. Although not every patient will develop haze without MMC, we continue to find it increasingly safe to prevent haze. The laser ablation profiles in modern excimer machines deliver less thermal damage than older versions, which may reduce the risk of haze; nevertheless, I always use MMC for all of my cases with surface ablation. Regarding the concentration and timing in my practice, MMC is applied at a con- centration of 0.02 mg/ml (0.02%) for 20 seconds over the ablated stromal bed, followed by a copious irrigation of saline. Most of my cases are for retreatment after LASIK so the depth of tissue ablation is less than the flap thickness after removal of epithelium to maintain the safety margin of the residual stromal bed. Editors’ note: Dr. Hutauruk declared no relevant financial interests. Harnessing - from page 63