SCLERAL MELT

Signs and Symptoms

Scleral melt—also known as scleral ischemia or scleral necrosis—is an uncommon condition that typically presents in older adults. In most cases, scleral melt represents a late complication of ophthalmic surgery and in such instances is more appropriately referred to as surgically induced scleral necrosis (SINS).1 It may also occur as a sequela of chemical or thermal trauma to the eye, or rarely as an isolated complication of systemic autoimmune disease.2 Clinically, the condition may be seen as a focal area of scleral thinning between the corneal limbus and the insertion of the extraocular muscles, with the dark blue/black coloration of the underlying uvea visible beneath the lesion. A variable degree of adjacent conjunctival inflammation may accompany scleral melt, depending upon the etiology and associated pathology.

Individuals presenting with scleral melt generally report symptoms of mild to moderate discomfort. Foreign body sensation, stinging and blurred vision are common, as are excessive lacrimation and possibly photophobia. Rarely do patients complain of intense ocular pain. No racial predilection has been identified. Women do appear to be affected more often than men.3 A history of systemic autoimmune disease is another common finding; some of the associated conditions may include rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa, inflammatory bowel disease, Wegener’s granulomatosis, relapsing polychondritis, diabetes mellitus and thyroid disorders.1-4

Pathophysiology

The most common predisposing factor in cases of scleral melt is prior ocular surgery. There is a particularly high association with pterygium excision, especially in those cases where either adjunctive radiation or chemotherapy was used.1,5,6 Scleral melt has also been described after cataract extraction, trabeculectomy, strabismus surgery, vitrectomy, retinal detachment repair, intravitreal implant surgery, orbital/ocular radiation and “eye-whitening” procedures.2,3,7-12 Alternatively, the patient may report a prior incident involving a severe chemical or thermal burn to the ocular surface. Scleral melt may occur as soon as one day or as late as 50 years after the antecedent trauma.13-15 Less commonly, scleral melt is encountered as a sequela of severe ocular surface disease (e.g., keratoconjunctivitis sicca), ocular infection, systemic vasculitis or connective tissue disorders.16-20

Scleral melt is presumed to represent a delayed-onset hypersensitivity response to localized ischemia involving the episcleral blood vessels.6 Such ischemia can be precipitated by surgical trauma (especially when accompanied by beta irradiation or mitomycin C therapy), chemical or thermal injury or less commonly, by severe autoimmune disease or vasculitis.2 The exact mechanism of damage is poorly understood, but enzymes produced by polymorphonuclear cells and stimulated by surgical manipulation are likely implicated, leading to destruction of collagen and proteoglycans that comprise the scleral stroma.1,10,18 Evidence to support these hypotheses include the success of systemic immunosuppression in the treatment of scleral melts, as well as the presence of immune complexes in the episcleral vessel walls among such patients.16,21 Research has identified elevated levels of both tumor necrosis factor alpha (TNF-) and MMP-9 in patients with surgically-induced scleral necrosis.22

Management

Therapeutic intervention in cases of scleral melt depends on a number of factors, most notably the disposition of the patient and the risk of global perforation. For those cases that are relatively asymptomatic and not in danger of rupture, periodic observation (e.g., every four to six months) along with liberal use of ophthalmic lubricants may be all that is required.2 However, patients in the postoperative period, such as pterygium resection with adjunctive antimetabolite, who present with a mild scleral melt should be evaluated sooner, preferably at one week. More severe cases may require the application of surgical patch grafts to maintain tectonic support of the globe.2

Tenonplasty, a surgical procedure involving excision of necrotic superficial tissue along with dissection and advancement of viable underlying Tenon’s capsule, is performed initially to reestablish the blood supply to the ischemic sclera. Then, donor sclera tissue or a lamellar corneal graft is typically transplanted to the wound and covered with either an amniotic membrane or a conjunctival flap.2,23,24 Postoperatively, treatment with topical corticosteroids (e.g., 1% prednisolone acetate QID) and prophylactic antibiotics (e.g., 0.5% moxifloxacin TID) helps control subsequent inflammation and infection.2 There has been some conjecture regarding the appropriatness of corticosteroids due to the belief that they may potentiate collagenases. Additionally, corticosteroids and NSAIDs have also been noted to cause scleral melt.

A variety of other surgical techniques have also been piloted, with varying success.24,25 The concurrent use of immunosuppressive agents such as oral cyclophosphamide, azithioprine, cyclosporin A and tacrolimus may be helpful to prevent graft rejection in difficult cases.26 Hyperbaric and normobaric oxygen therapy have also been used in patients who failed to respond as desired to medical or surgical intervention.27,28

In cases of scleral melt that do not have an obvious traumatic or iatrogenic etiology, and especially in those cases that involve the limbal and peripheral corneal regions, a medical workup to rule out associated systemic disease is essential. According to a landmark study, as many as 63% of scleral melt cases are associated with an underlying medical disorder, of which the most common group is connective tissue diseases such as rheumatoid arthritis, Wegener’s granulomatosis, or polyarteritis.29-31

Clinical Pearls

Scleral melt is a serious and challenging clinical problem, as it threatens the integrity of the eye. Even asymptomatic cases likely warrant a surgical consultation to assess the potential for perforation.

Numerous conditions can masquerade as scleral melt. These include benign entities such as senile scleral plaques and dellen, as well as more serious conditions including ciliary body melanoma and scleromalacia perforans.

Scleromalacia perforans can be differentiated from scleral melt in that patients with the former are generally asymptomatic and present with bilateral involvement. In addition, the eyes are usually otherwise quiet in patients with a chronic history of rheumatoid arthritis.

1. Doshi RR, Harocopos GJ, Schwab IR, Cunningham ET Jr. The spectrum of postoperative scleral necrosis. Surv Ophthalmol. 2013;58(6):620-33.

2. Casas VE, Kheirkhah A, Blanco G, et al. Surgical approach for scleral ischemia and melt. Cornea. 2008;27(2):196-201.

3. Tamhankar MA, Volpe NJ. Atypical necrotizing scleritis after strabismus surgery. J AAPOS. 2008;12(2):190-2.

4. Ozcan AA, Bilgic E, Yagmur M, et al. Surgical management of scleral defects. Cornea. 2005;24(3):308-11.

5. Aydin A, Aksoy Y, Unal MH, Ersanli D. Necrotizing scleritis after pterygium surgery using mitomycin C. J Fr Ophtalmol. 2012;35(1):74-5.

6. Jain V, Shome D, Natarajan S, et al. Surgically induced necrotizing scleritis after pterygium surgery with conjunctival autograft. Cornea. 2008;27(6):720-1.

7. Das S, Saurabh K, Biswas J. Postoperative necrotizing scleritis: a report of four cases. Middle East Afr J Ophthalmol. 2014;21(4):350-3.

8. Huang CY, Lin HC, Yang ML. Necrotizing scleritis after strabismus surgery in thyroid eye disease. J AAPOS. 2013;17(5):535-6.

9. Morley AM, Pavesio C. Surgically induced necrotising scleritis following three-port pars plana vitrectomy without scleral buckling: a series of three cases. Eye (Lond). 2008;22(1):162-4.

10. Georgalas I, Koutsandrea C, Papaconstantinou D, et al. Scleral melt following Retisert intravitreal fluocinolone implant. Drug Des Devel Ther. 2014;8:2373-5.

11. Leung TG, Dunn JP, Akpek EK, Thorne JE. Necrotizing scleritis as a complication of cosmetic eye whitening procedure. J Ophthalmic Inflamm Infect. 2013;3(1):39.

12. Moshirfar M, McCaughey MV, Fenzl CR, et al. Delayed manifestation of bilateral scleral thinning after I-BRITE procedure and review of literature for cosmetic eye-whitening procedures. Clin Ophthalmol. 2015;9:445-51.

13. Iovieno A, Anand S, Dart JK. Late-onset peripheral ulcerative sclerokeratitis associated with alkali chemical burn. Am J Ophthalmol. 2014;158(6):1305-9.

14. Lai T, Leibovitch I, Zadeh R, et al. Surgically induced necrotizing scleritis occurring 48 years after strabismus surgery. J Pediatr Ophthalmol Strabismus. 2005;42(3):180-2.

15. Mahmood S, Suresh PS, Carley F, et al. Surgically induced necrotising scleritis: report of a case presenting 51 years following strabismus surgery. Eye (Lond). 2002;16(4):503-4.

16. Gungor IU, Ariturk N, Beden U, Darka O. Necrotizing scleritis due to varicella zoster infection: a case report. Ocul Immunol Inflamm. 2006; 14(5):317-9.

17. Shome D, Jain V, Jayadev C, et al. Scleral necrosis in a patient with aplastic anaemia. Eye. 2007;21(7):1017.

18. Schotveld JH, Beerthuizen JJ, Zaal MJ. Scleral melting in a patient with carotid artery obstruction. Cornea. 2006;25(1):101-3.

19. Christakopoulos C, Heegaard S, Saunte JP. Surgically induced necrotizing scleritis in Wegener’s granulomatosis. Acta Ophthalmol. 2014;92(7):e588-9.

20. Gu J, Zhou S, Ding R, et al. Necrotizing scleritis and peripheral ulcerative keratitis associated with Wegener’s granulomatosis. Ophthalmol Ther. 2013;2(2):99-111.

21. Diaz-Valle D, Benitez del Castillo JM, Castillo A, et al. Immunologic and clinical evaluation of postsurgical necrotizing sclerocorneal ulceration. Cornea. 1998;17(4):371-5.

22. Seo KY, Lee HK, Kim EK, et al. Expression of tumor necrosis factor alpha and matrix metalloproteinase-9 in surgically induced necrotizing scleritis. Ophthalmic Res. 2006;38(2):66-70.

23. Ti SE, Tan DT. Tectonic corneal lamellar grafting for severe scleral melting after pterygium surgery. Ophthalmology. 2003;110(6):1126-36.

24. Esquenazi S. Autogenous lamellar scleral graft in the treatment of scleral melt after pterygium surgery. Graefes Arch Clin Exp Ophthalmol. 2007;245(12):1869-71.

25. Davidson RS, Erlanger M, Taravella M, et al. Tarsoconjunctival pedicle flap for the management of a severe scleral melt. Cornea. 2007;26(2):235-7.

26. Young AL, Wong SM, Leung AT, et al. Successful treatment of surgically induced necrotizing scleritis with tacrolimus. Clin Experiment Ophthalmol. 2005;33(1):98-9.

27. Oguz H, Sobaci G. The use of hyperbaric oxygen therapy in ophthalmology. Surv Ophthalmol. 2008;53(2):112-20.

28. Sharifipour F, Panahi-Bazaz M, Idani E, et al. Normobaric oxygen therapy for scleral ischemia or melt. J Ophthalmic Vis Res. 2012;7(4):275-80.

29. O’Donoughue E, Lightman S, Tuft S, et al. Surgically induced necrotising sclerokeratitis (SINS) – precipitating factors and response to treatment. Br J Ophthalmol. 1992;76(1):17-21.

30. Atchia II, Kidd CE, Bell RW. Rheumatoid arthritis-associated necrotizing scleritis and peripheral ulcerative keratitis treated successfully with infliximab. J Clin Rheumatol. 2006;12(6):291-3.

31. Choi W, Lee SS, Park YG, Yoon KC. A case of necrotizing keratoscleritis in primary Sjogren’s syndrome. Korean J Ophthalmol. 2011;25(4):275-7.