Because of prolonged ocular surface morbidities, corneal perforations in severe SJS still face great challenge of recurrence, and the final visual function is always pessimistic. In this series of 10 patients, the corneal perforations were successfully repaired with MSTK and conjunctival flap in 9 patients. Tarsorrhaphy was required for remedial reason in one patient with conjunctival flap failure to adhere to the corneal lesion. All corneal grafts remained stable during the follow-up of no less than 1 year, and improved vision was acquired in more than 50% of the cases.
Efficacy of AMT in treating small corneal perforation has been well established but unable to promote corneal stability in patients with severe corneal thinning
. Also, because the amniotic membrane cannot control corneal melting effectively in dry eyes
, it does not seem to work well in patients with SJS
[6, 10], which was further confirmed in 6 patients in this study. Conjunctival flaps could be used for small eccentric corneal perforations
, but could not seal large corneal perforations associated with corneal melting because the leap would continue under the flap
[19, 20]. Things were the same for 7 patients in this study. Tissue adhesives are effective for corneal perforations in a diameter of less than 2 mm but not for those chronic, deep ulcers, and the toxicity may worsen inflammatory reaction
Traditional orthotopic PK, using a large-diameter graft, could achieve comparable anatomical and functional success in treating corneal perforation. But in patients with severe SJS, the corneal grafts are facing high risk of immune rejection, persistent epithelial defection, infection, graft melting, and resultant recurrence of corneal perforation
. Tugal-Tutkun et al. reported PK, with grafts of 7.5 mm to 14 mm, for cicatrizing conjunctival diseases in 13 eyes, among which three out of four grafts in patients with SJS failed and required additional procedures
. Theoretically, the smaller the size of a corneal graft, the greater is the chance of its survival. Soong et al. reported 3 cases of fistulous wound leaks after cataract surgery successfully treated with small diameter corneal grafts for tectonic reasons
. Similar procedures were performed by Chern in treating various peripheral corneal disorders with small-diameter, round, eccentric PK
. We previously modified this technique by preserving the deep stroma, Descemet’s membrane, and the endothelium of the corneal bed as much as possible, so that glycerin-cryopreserved grafts could be used with ultimate transparency
. But all the corneal grafts used in the reported cases had the same size as corneal lesions, and all the eyes had a relative fertile ocular surface. The single case with ocular surface disorder reported by Chern et al. developed epithelial keratopathy and required further treatment
. In this study, two patients had been treated with repeated small corneal graft transplantation, but both failed in graft melting and recurrence of corneal lesions. Therefore, small corneal grafts in patients with severe ocular disorders still risk graft failure.
Corneal perforations in SJS are usually developed from corneal melting, and there is commonly an irregular corneal lesion, much larger than corneal perforation, which is usually apparent on HD-OCT examination (Figure
1A). If corneal grafts are prepared according to the corneal ulcer, certainly much larger than the perforation, the risk of graft failure would inevitably increase. In view of the characteristics of corneal perforation in SJS, we hypothesized that the diameter of corneal graft could be further reduced just to repair the perforation. In our experience, grafts can be well sutured as long as the thickness of the edge of the recipient bed is more than two-thirds of the cornea. Hence, instead of trying to cover the entire ulcer, we selected a trephine according to the shortest path through the central ulcer in which the remaining stromal thickness was more than two-thirds of the cornea (Figure
1B and C). In this study, all the 10 corneal grafts were successfully transplanted to the recipients, which indicate the feasibility of corneal transplantation with a reduced-size corneal graft.
Due to the fact that the corneal graft was much smaller than the ulcer, a ‘ditch’ was left around the graft (Figure
1C*). The epithelium of the recipient was expected to step across the ditch to cover the graft, which was a difficult task in the eye with severe ocular surface disorder. To prevent secondary infection and to enable repair of the ditch between the graft and the corneal bed, an effective epithelial barrier must be provided. Also, a sufficient source of nutrients was necessary to ensure the survival of corneal graft. AMT, with the function of promoting epithelialization and decreasing inflammation, neovascularization and fibrosis
, was a potential selection. But its function would disappear with the amniotic membrane melting within one month after transplantation. Tarsorrhaphy could improve re-epithelialization and prevent corneal melting
, but it is not acceptable for most patients for poor cosmetic appearance. Moreover, it could interfere with the observation of corneal lesions. So tarsorrhaphy was selected only when there were no other choices. Conjunctival flap, rich in blood vessels, is effective in treating refractory corneal ulcers. Although cosmetic appearance was poor over a period of time after surgery, the conjunctival flap would have a marked regression after healing of corneal lesions
, and there is not any difference between conjunctival flap blood vessels and corneal neovascular results from severe SJS. Ultimately, the cosmetic appearance and impairment of corneal clarity after conjunctival flap covering are acceptable for most patients. Therefore, in this study, conjunctival flap was used for protective reasons. No one complained about the cosmetic appearance of conjunctival flap.
In this case series, MSTK combined with conjunctival flap achieved favorable effects. The success of this combined procedure may be attributed to the following aspects. First, the corneal graft was quite small, which resulted in a lower risk of immune rejection and melting. Second, the corneal graft restored the integrity of the eye and added a rigid barrier between the aqueous humor and the conjunctival flap, which facilitated adherence of conjunctival flap to the corneal lesions. Third, the conjunctival flap helped to prevent secondary infection by covering the space around the small-diameter corneal graft. Fourth, the flap aided in the absorption of necrotic tissues and promoted vascularization of the wounded cornea
, thus preventing graft melting and the extension of remaining ulcers. In the only case with conjunctival flap failure, corneal epithelial reconstruction was delayed, and an additional procedure was required, which indicates the importance of conjunctival flap in this combined procedure.
Due to the complexity of corneal perforations in SJS, most patients may have poor visual acuity after treatment, and additional treatment for improving eyesight can be performed. Moreover, conjunctival flaps could not be obtained for protective necessities in patients who do not have enough healthy conjunctivas. Hence, permanent tarsorrhaphy would eventually be resorted to.