Scleral dellen after bilateral adjustable suture medial rectus muscle resection

Scleral Dellen After Bilateral Adjustable Suture Medial Rectus Muscle Resection Dave H. Lee, MD, Michael A. Herion, MD, Donald R. Unwin, MD, and Oscar A. Cruz, MD alone would be sufficient. The conjunctiva was undermined Ocular complications after strabismus surgery in a large study population were recently reported.1 The most frequent of these complications included pseudoptosis, corneal dellen, conjunctival folds, and punctate epithelial keratopathy. We report the occurrence of a rare complication, scleral dellen, occurring in a healthy 30-year-old man after bilateral adjustable suture medial rectus muscle resection for residual exotropia.

and mobilized over the area of scleral thinning. The patient’s eye was patched overnight. Despite aggressive lubrication, there was a slow re-recession of the conjunctiva that showed an area of persistent scleral thinning. The patient underwent repeat conjunctivoplasty, performed identically to the initial procedure. This resulted in excellent coverage of the defect with conjunctiva. During the next 2 months, there was complete resolution of the scleral defect.

CASE REPORT

DISCUSSION

A 30-year-old white man was referred for evaluation of progressively worsening exotropia and diplopia. He was otherwise healthy and had no previous ocular or systemic surgeries. Examination showed visual acuity of 20/20 in both eyes, normal slit lamp and dilated fundus examination in both eyes, and 35 prism diopters of an intermittent right exotropia. The patient underwent a 7.5-mm bilateral lateral rectus recession through a limbal peritomy using a “bowtie” adjustable suture technique. By 2 months after surgery, the patient developed a 35–prism diopter residual exotropia despite orthoptic convergence exercises. A bilateral medial rectus resection of 6.0 mm was then carried out through a limbal peritomy using a “bowtie” adjustable suture technique. Early postoperative alignment was excellent. On postoperative day no. 6, the patient returned complaining of a 3-day history of a “blue dot” on the medial aspect of his left eye. This was associated with minimal pain and was relieved with over-the-counter medications. Examination showed visual acuity of 20/20 in both eyes. Slit lamp biomicroscopy of the left eye revealed recessed conjunctiva medially with an area, 1.9 mm ⫻ 1.5 mm, of severe scleral thinning between the limbus and the adjustable Vicryl (Ethicon Inc, Somerville, NJ,) suture knot (Figure 1). Because of the impressive extent of this lesion, scleral patch grafting was considered. However, our external disease specialist agreed that with the low risk of perforation in scleral dellen, conjunctivoplasty with aggressive lubrication

Scleral dellen results from local dehydration of the scleral tissues much like local desiccation of the cornea results in the more commonly recognized corneal dellen.2 Thinning of the scleral tissues with resultant exposure of the underlying uvea leads to the bluish color. Although perforation of the globe appears imminent in these patients, to the best of our knowledge, there are no such reports in the literature. In fact, scleral dellen is a benign condition. The importance of recognizing scleral dellen as a possible complication after ocular surgery lies primarily in its differentiation from other eye-threatening complications, notably, surgically induced necrotizing scleritis (SINS). This condition has been reported to occur after a variety of ocular operations including strabismus surgery, pterygium excision, and cataract extraction.3-5 Many of the features that distinguish SINS from scleral dellen are summarized in a review by Donoghue et al.6 These include pain on presentation, marked local inflammation, association with systemic disease, and longer time after surgery before presentation of typical clinical features. Treatment usually requires prolonged immunosuppressive therapy. Once a diagnosis of scleral dellen is made, appropriate definitive treatment may be initiated. The goal of therapy in this condition is rehydration of the sclera. This can often be achieved with aggressive topical lubrication alone. Some patients may be refractory to such treatment secondary to physical impediments to proper tear film distribution. In our patient, we felt that the recessed conjunctiva and adjacent Vicryl suture acted as such an impediment. Mobilization of the conjunctiva creates an even surface for lubrication as well as a protective barrier for the sclera. It is easy to perform and may be done in the office using topical anesthesia. Patching may also be of some value.7 Scleral dellen may be preventable by paying careful attention to surgical technique. When purposefully recessing the conjunctiva in surgery involving a limbal peritomy, the edges of conjunctiva should be as flat as possible. This

From the Department of Ophthalmology, Saint Louis University Eye Institute, St. Louis, Missouri. Submitted August 23, 2002. Revision accepted December 11, 2002. Reprint requests: Oscar A. Cruz, MD, Saint Louis University Eye Institute, 1755 S Grand Blvd, St. Louis, MO 63104. Copyright © 2003 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/2003/$35.00 ⫹ 0 doi:10.1016/S1091-8531(03)00004-1

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FIG 1. A, Left eye 6 days after bimedial rectus resection on an adjustable Vicryl suture for residual exotropia showing an area, 1.9 mm ⫻ 1.5 mm, of severe thinning of the sclera between the limbus and knot of Vicryl suture. B, Closer view of scleral dellen.

is particularly true in a resection, where the conjunctiva is naturally elevated. Alternatively, a fornix-based adjustable suture technique can be employed.8 Despite aggressive management and an ultimately excellent outcome, it is unclear why our patient had a prolonged recovery relative to other cases in the literature.2,7 Disruption of the episcleral vessels has been implicated as a contributing factor in the formation of scleral dellen.2 This was supported in part by an unrestricted grant from Research to Prevent Blindness. References 1. Scharwey K, Graf M, Becker R, Kaufmann H. Healing process and complications after eye muscle surgery. Ophthalmologe 2000;97(1): 22-6.

2. Sharma P, Arya AV, Prakash P. Scleral dellen in strabismus surgery. Acta Ophthalmologica 1990;68:493-4. 3. Kaufman LM, Folk ER, Miller MT, Tessler HH. Necrotizing scleritis following strabismus surgery for thyroid ophthalmopathy. J Pediatr Ophthalmol Strabismus 1989;26:236-8. 4. Galanopoulos A, Snibson G, O’Day J. Necrotising anterior scleritis after pterygium surgery. Aust N Z J Ophthalmol 1994;22(3): 167-73. 5. Beatty S, Chawdhary S. Necrotizing sclerokeratitis following uncomplicated cataract surgery. Acta Ophthalmol Scand 1998;76:382-3. 6. O’Donoghue E, Lightman S, Tuft S, Watson P. Surgically induced necrotising sclerokeratitis (SINS)-precipitating factors and response to treatment. Br J Ophthalmol 1992;76:17-21. 7. Hicks RR, Irvine AR, Spencer WH, Yuhasz Z. Scleral dellen. Arch Ophthalmol 1975;93:88-9. 8. Wright KW, McVey JH. Conjunctival retraction suture for fornix adjustable strabismus surgery. Arch Ophthalmol 1991;109:138-41.