Conjunctival suture granuloma following glaucoma surgery

INTRODUCTION

Conjunctival suture granuloma is a localized inflammatory reaction that typically results from a localized foreign body reaction to retained or partially absorbed suture material. The pathogenesis of suture granulomas is a granulomatous inflammatory response to the foreign body material, with lymphocytes and multinucleated giant cells surrounding and encasing synthetic suture fibers.^[1] While conjunctival suture granulomas are typically linked to nonabsorbable sutures such as polyester and nylon, cases have also been reported following the use of absorbable materials such as Vicryl polyglactin suture.^[2,3] Risk factors of conjunctival pyogenic granuloma formation in general include conjunctival surgery and pregnancy, and granulomas are more common in children and young adults; however, the exact cause remains unknown.^[3]Possible outcomes of pyogenic granuloma can include spontaneous regression, recurrence, or rarely infection.^[4]

In glaucoma filtering surgeries, such as trabeculectomy or glaucoma drainage device (GDD) implantation, conjunctival closure is a critical step in ensuring a watertight seal and preventing post-operative hypotony or infection. Absorbable suture materials such as Vicryl are commonly used to approximate the conjunctival margins in glaucoma surgery as they provide adequate tensile strength to hold the membrane in place without requiring removal of the suture.^[5]

This case series describes the rare entity of conjunctival suture granuloma formation following glaucoma surgery with conjunctival closure with 8-0 Vicryl suture. These cases demonstrate the possibility of an inflammatory reaction from absorbable suture that may occur after glaucoma surgery and make surgeons aware of this complication that may mimic infection.

CASE SERIES

Case 1

A 91-year-old Caucasian woman with pseudoexfoliative glaucoma underwent a 13 mm by 16 mm valved Ahmed Glaucoma Valve Model FP7 placement with 8-0 Vicryl conjunctival closure in the right eye. Preoperatively, the patient was on bimatoprost daily, dorzolamide-timolol twice a day, and brimonidine twice a day in both eyes. Selective laser trabeculoplasty was performed in the right eye; however, the intraocular pressure remained elevated at 46 mmHg 1 week after the procedure while on the topical intraocular pressure-lowering drops and ketorolac. Thus, a GDD was indicated for intraocular pressure control. The conjunctiva was white and quiet preoperatively, while the cornea had 1+ Descemet folds and 2+ anterior basement membrane dystrophy (ABMD) in the right eye.

The implant was placed in the following fashion: First, a corneal traction suture was placed with 7-0 Vicryl. The superotemporal quadrant was opened with conjunctival and Tenon’s peritomy. The drainage device was sutured 8 mm from the limbus with 7-0 Vicryl, trimmed, and then entered the anterior chamber through a 23-gauge needle entrance site. A piece of half-moon split-thickness cornea was secured over the drainage device with 7-0 Vicryl. The conjunctiva was closed with 8-0 Vicryl on a blood vessel (BV) needle with a running suture technique. Pre-operative visual acuity was 20/200 in the right eye. On post-operative day 1, the visual acuity was 20/200 in the right eye, the intraocular pressure was 11, and the tube was well covered on examination. On postoperative day 2, she had mucoid discharge and lash crusting, but the conjunctiva was intact with the tube well covered. She was placed on doxycycline 100 mg and advised to clean the lids with sterile gauze and balanced salt solution (BSS). She was continued on the standard post-operative regimen of topical moxifloxacin and prednisolone acetate 4 times a day. On postoperative day 6, the patient reported occasional foreign body sensation. Examination revealed purulence along the suture line without signs of endophthalmitis [Figure 1a]. The suture was intact and there was no wound leak. At this time, visual acuity in the affected eye was 20/200. The patient was placed on topical moxifloxacin 0.5% every hour (h) and oral moxifloxacin 400 mg daily. On post-operative day 7, there were white ropey changes on the lateral suture line consistent with granuloma. 0.2 mL of 0.5% subconjunctival moxifloxacin was administered and she was continued on topical moxifloxacin 0.5% every 2 h. She was continued on topical prednisolone acetate 1% 4 times a day. Bacterial cultures taken from the conjunctival site on postoperative day 6 had no growth in 2 days.

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Figure 1: (a) Suture granuloma on post-operative day 6. (b) Conjunctival appearance on post-operative day 13. (c) Healed conjunctiva at 1-month post-operative.

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At 1 week after presentation (6 days after subconjunctival moxifloxacin), the granuloma was improving, determined by improved injection and reduced white appearance to the suture line on slit lamp examination, as demonstrated in Figure 1b. The patient was deemed to have a conjunctival suture granuloma and was maintained on topical moxifloxacin and prednisolone 4 times a day. In post-operative week 3, the granuloma continued to improve with reduced inflammatory appearance. Her topical moxifloxacin was stopped, and prednisolone was decreased to twice a day. At post-operative month 1 follow-up, there was resolution of the granuloma with well-healed, quiet conjunctiva. The suture was dissolving. She was tapered off topical prednisolone therapy by decreasing from twice a day to once a day at post-operative month 1. At post-operative month 5, the patient was misusing prednisolone at 4 times a day instead of once a day and had an intraocular pressure spike to 34 mmHg. The prednisolone was stopped at this visit and her intraocular pressure was decreased with topical therapy and oral acetazolamide. There was no recurrence of the granuloma throughout the follow-up period through 1-year post-operative. Slit-lamp photograph of the conjunctiva at 1-year post-operative is shown in Figure 1c. One year postoperatively, her vision is unchanged at 20/200 in the affected eye.

Case 2

A 66-year-old African American man with severe primary open-angle glaucoma underwent Combined 13 × 16 mm Ahmed Glaucoma Valve Model FP7 placement with phacoemulsification and intraocular lens placement with 8-0 Vicryl conjunctival closure. Pre-operative visual acuity in the affected eye was count fingers at 1 foot. The patient was on brimonidine 3 times a day in both eyes, dorzolamide-timolol twice a day in both eyes, latanoprost once daily in both eyes, and netarsudil once daily in both eyes; however also had a history of non-compliance with variability in intraocular pressure measurement. The intraocular pressure was 23 mmHg in the right eye. GDD with phacoemulsification was indicated for long-term intraocular pressure control in the setting of severe glaucoma with intermittent medication non-compliance. Preoperatively, meibomian gland dysfunction was present with quiet conjunctiva and clear cornea.

The GDD was placed in the following fashion after the phacoemulsification portion of the procedure was completed and the corneal incision was closed with 10-0 nylon suture: First, a corneal traction suture was placed with 7-0 Vicryl suture. The superotemporal quadrant was opened with a conjunctival and Tenon’s peritomy, and the GDD was placed approximately 10 mm posterior to the limbus with 7-0 Vicryl sutures at two fixation points. The GDD was cut to the appropriate length and entered into the anterior chamber through a 23-gauge needle tract. Half-thickness donor sclera was sutured over the GDD with 7-0 Vicryl suture. The conjunctiva was closed with 8-0 Vicryl suture on a BV needle with a running suture technique.

On post-operative day 1, examination was notable for subconjunctival hemorrhage superiorly, with no suture leak. On post-operative day 5, he experienced eye discomfort, photophobia, and his visual acuity was reduced to hand motion in the affected eye. Slit-lamp examination was notable only for chemosis at this time; thus, the patient was monitored closely on a routine post-operative treatment regimen of topical 0.5% moxifloxacin and 1% prednisolone acetate 4 times a day. On post-operative day 11, examination revealed an inflamed conjunctiva with purulence along the suture [Figure 2a]. There was no evidence of endophthalmitis or any change in visual acuity from the previous visit. He was not reliably receiving his topical prednisolone and moxifloxacin at his facility. 0.2 mL of 0.5% subconjunctival moxifloxacin was administered. Culture was not obtained. At post-operative day 12, examination was unchanged and appeared consistent with a pyogenic granuloma to the Vicryl suture. His visual acuity was count fingers at 6 inches. 0.2 mL of subconjunctival triamcinolone acetonide 40 mg/mL was administered, and the topical prednisolone acetate was increased to 6 times a day. The facility was called and instructed on the proper medication regimen. At post-operative month 1, the patient was comfortable with a quiet conjunctiva, dissolving suture, and resolution of suture granuloma [Figure 2b]. Visual acuity in the affected eye had improved to count fingers at 5 feet. The topical prednisolone acetate was decreased to 3 times a day. There was no recurrence at post-operative month 2. The patient was then lost to follow-up.

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Figure 2: (a) Appearance of conjunctiva at initial presentation at 11-day post-operative. (b) Healing conjunctiva at 1-month post-operative.

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DISCUSSION

Suture granuloma formation is rare, with only a handful of cases reported.^[6,7] We report two cases of suture granuloma formation in the immediate post-operative period following GDD with Vicryl suture closure. One case improved with topical prednisolone, while the other necessitated subconjunctival triamcinolone. Conjunctival surface infection must be considered in the differential early in the course of a granuloma, and these cases were treated initially with topical antibiotics as well as subconjunctival moxifloxacin due to concern for infection. Case 2 was treated with both subconjunctival moxifloxacin and subsequently subconjunctival triamcinolone. The implication from these cases is that conjunctival surface inflammation after glaucoma surgery may be related to granuloma formation even with absorbable suture closure; thus, granuloma must be considered as a possibility during the post-operative course. Steroid therapy resolved the granuloma in these cases.

To the authors’ knowledge, two cases have been reported in the literature of conjunctival granuloma following glaucoma surgery. One case presented a 4-month post-operative period after an Aurolab aqueous drainage implant with a granuloma formed from a 5-0 Prolene suture. It was treated initially with a combination of antibiotic-steroid drops and then suture removal.^[6] In our cases, the granuloma formed from Vicryl suture in the immediate post-operative period.

The second case developed after combined trabeculectomy and phacoemulsification, related to retained microfragments of the mitomycin-C cellulose sponge. The conjunctiva was closed with 10-0 nylon during the surgery. Three weeks postoperatively, the patient presented with pain and redness, and a granuloma was located adjacent to the bleb. The suture was removed and the granuloma treated with both topical and oral steroids.^[7]

Only one other case of suture granuloma after absorbable suture placement has been described in a 13-year-old female after bilateral medial rectus recession. It did not improve with topical prednisolone, then was treated with topical timolol 0.5% with improvement and subsequent complete regression in 3 months.^[3] Granuloma formation around a suture is rare and even more novel to occur with absorbable sutures.

CONCLUSION

Conjunctival suture granuloma is a rare complication of ocular surgery, most often reported after strabismus and pterygium surgeries, and with non-absorbable sutures. Our cases demonstrate the potential for conjunctival granuloma formation after absorbable suture placement in Ahmed Glaucoma Valve surgery. Suture granuloma should be included in the differential diagnosis for post-operative ocular surface inflammation. Treatment with topical and/or subconjunctival corticosteroids may be necessary for complete resolution.