Materials and results

All patients were referred to Joint international eye center of Shantou University and The Chinese University of Hong Kong. Surgical methods were scleral patch graft, combined autologous conjunctival pedicle transposition at the same time if necessary. Allogeneic scleras, which were glycerol cryopreservation, were provided by the eye bank of Joint international eye center of Shantou University and The Chinese University of Hong Kong. The minimum age of the patient was 3 years old, and the maximum was 74 years old. The average age was 50 years old. Three 

Figure 1 Scleral staphyloma after corneal dermoid resection. (A) Pre-op; (B) UBM pre-op; (C) post-op. UBM, ultrasound biomicroscopy.

Figure 2 Scleral staphyloma after pterygium excision and conjunctival autograft without MMC. (A) Pre-op; (B) post-op. MMC, Mitomycin C.

Figure 3 Scleral staphyloma after traumatic cataract surgery. (A) Pre-op; (B) UBM pre-op; (C) post-op. UBM, ultrasound biomicroscopy.

Figure 4 Scleral staphyloma after cataract surgery. (A) Pre-op; (B) anterior segment optical coherence tomography (AS-OCT) pre-op; (C) post-op; (D) 1 month post-op.

Anatomically corneal dermoids have been classified into three grades: Grade I limbal or epibulbar dermoid are lesions with a superffcial tumor measuring less than 5 mm. Grade II limbal dermoids are of larger size and extend into the corneal stroma down to Descemet’s membrane. Grade III limbal dermoids involve the whole cornea and structures of the anterior chamber. Visual acuity may be reduced due to the presence of coexisting amblyopia, astigmatism, and obscuration of the visual axis by the tumor. Irritation by the protruding cilia may also be a presenting feature. In the past, several different surgical techniques for the removal of dermoids have been described ⁽³⁾. These techniques include bare excision, amniotic membrane transplantation, and even lamellar and penetrating keratoplasty. The adequate choice depends on the location and size of the lesion. Major risks of the excision of the limbal dermoid are intraoperative perforation, postoperative epithelial defects and peripheral vascularization of the cornea ⁽³⁾. Lamellar keratoplasty is reported to result in the improvement of visual acuity, but may also lead to graft opaciffcation, graft ectasia, corneal donor melt, and astigmatism ^(4,5). The conventional method of treatment for dermoids is a simple excision or a shaving operation. However, complications including postoperative scars with neovascularization or pseudopterygium have been frequently noted ⁽⁶⁾. The prerequisite is superficial tumors and the remaining corneoscleral is thick enough. In this 3-year-old young girl, she presented scleral staphyloma 1 year after pterygium surgery. We speculate that the main cause may be a thin remaining sclera. In addition, the growth and development of the eye cannot be ignored.
Pterygium excision with conjunctival autograft is a commonly performed procedure for the treatment of primary and recurrent pterygia. Scleral necrosis and melting can occur after pterygium surgery due to the use of adjunctive irradiation, mitomycin C, or excessive cauterization of the sclera ⁽²⁾. It is also believed to be a delayed-type hypersensitivity response to surgical trauma or ischemia that exposes tissue antigens, thereby sensitizing the immune system ⁽⁷⁾. In this case, no radiation or mitomycin C was used, and No systemic history was reported. The patient presented foreign body sensation and prick pain on the operational eye 2 weeks postoperatively. No evidence of infectious scleritis presented. We speculate that Sclera cauterization and ischemia may play an important role. It could not alleviate the symptoms after systemic medicine. An operation was strongly requested because local discomfort seriously affects her life. 
Cataract surgery was another cause of sclera staphyloma, even though very rare. Sutured incision was malaligned and the top of the iris prolapsed, formed an incarceration. Although the IOP was low, the tissues including the sclera, choroid, or the iris protruded, expanding outward and ffnally forming a scleral staphyloma that resembled a purple black grape-shaped bulge, all secondary to postoperative damage to the eyeball wall that led to reduced resistance ⁽¹⁾. This may be the main reason for the formation of the anterior scleral staphyloma in those patients. The cases we report has similar characteristics to that described by Zheng and associates ⁽¹⁾ that showed formation of a ciliary staphyloma induced by a corneoscleral tunnel incision cracking following cataract surgery.
Zheng Q ⁽¹⁾ reported successfully treat sclera staphyloma by combined anterior sclera staphylectomy and vitrectomy. The patient might present greater postoperative astigmatism. In addition, it might increase the chance of retinal detachment. Yalçindag ⁽⁸⁾ reported to repair sclera staphyloma with dehydrated dura mater patch graft. Ozcan ⁽⁹⁾ reported successfully treat scleral defects using fascia lata, cornea, and sclera as graft materials. However, both dura mater and fascia lata were not easy got in our hospital. Polat ⁽¹⁰⁾ reported successfully use of an autologous lamellar scleral graft to repair a scleral melt, but it was limited to a relatively small graft. All our patients were still slow progress, and Symptoms could not be relieved even after systemic medicine. The operation of Sclera patch graft was performed in all four patients, three of them combined autologous conjunctival pedicle transposition. In the at least half a year follow-up, the BCVA of all the four patients were no worse than that of preoperative. Ocular symptoms disappeared, including eye pain, foreign body sensation, and so on. Unfortunately, the fourth patient showed partial sclera dissolution 1 month postoperative. We speculate that the main cause may be sclera rejection and ischemia. Fortunately, scleral dissolution did not aggravate after the systemic use of postoperative topical corticosteroids, immunosuppressants and Chinese traditional medicine for systemic vasodilatory. Surgical intervention was not accepted and the patient is still in follow-up.
Our study has some limitations, including its retrospective design, the small number of patients, and the lack of a control group. Despite this, we can conclude that scleral staphyloma must be considered in the patients following corneal dermoid, pterygium, and cataract surgery, even rare. Allogeneic scleral patch is one of the methods for treating scleral staphyloma. However, scleral rejection and dissolution should be considered postoperatively.