Sir,

Bleb-forming filtration procedures, such as trabeculectomy, combined phacotrabeculectomy, and trabeculectomy revision by needling, are surgical options in medically uncontrolled glaucoma. Postoperative topical steroid significantly increased the chance of filtration success1, 2, 3 by inhibiting fibroblast proliferation.4 Topical steroid application, however, requires compliance by and dexterity of the patient. Direct injection of triamcinolone acetonide (TA) into the bleb at the conclusion of surgery may be a more direct, sustained, and convenient mode of steroid delivery. The bulk of injected TA also serves as a barrier between the inflamed conjunctiva and sclera. This pilot study evaluates whether intrableb injection of TA is an effective and safe route for steroid application after bleb-forming filtration surgery.

Case reports

In consecutive glaucoma patients undergoing trabeculectomy, phacotrabeculectomy, and needling revision by the same surgeon (CT) during the study period of 3 months, 0. 03 ml of TA (Kenacort-A IM, Bristol-Myers Squibb) (40 mg ml−1) was injected using a bent 27-G needle into the filtration bleb at the conclusion of surgery. The entry site for the injection needle was at least 1 cm from the scleral flap, and covered by the upper eyelid. The injection needle was passed between the conjunctiva and the sclera towards the scleral flap. The TA was injected immediately adjacent and posterior to the scleral flap (Figure 1). Postoperative topical corticosteroid (Pred Forte, Allergan) was prescribed four times a day, because of the uncertain efficacy of intrableb TA injection.

Figure 1
figure 1

Subconjunctival injection of TA immediate adjacent and posterior to the scleral flap at the conclusion of bleb-forming filtration surgery.

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Eleven eyes of 11 patients were recruited (seven men and four women). Mean age±standard deviation was 57.4±19.7 years. Their diagnoses included primary open-angle glaucoma (five eyes) and chronic angle-closure glaucoma (six eyes). Three eyes underwent phacotrabeculectomy (with mitomycin C 0.4 mg ml−1 applied to sclera for 3 min), three eyes underwent trabeculectomy (with mitomycin C 0.4 mg ml−1 applied to sclera for 3 min), and five eyes underwent needling revision (with single intraoperative subconjunctival injection of 5 mg 5-fluorouracil).

Mean intraocular pressure (IOP) was reduced from 23.7±7.1 mmHg (range, 9–34 mmHg) preoperatively to 12.2±5.7 mmHg (range, 5–20 mmHg) at 1 month and 11.9±5.1 mmHg (range, 5–20 mmHg) at 3 months after surgery. The mean number of topical glaucoma drugs was reduced from 3.4±1.0 (range, 2–5) preoperatively to 0 in all eyes at both 1 month and 3 months.

There was minimal postoperative anterior segment inflammation in all cases. Microcystic and spongy blebs were achieved in all cases.

All corneas were clear before surgery, and at 1 and 3 months after surgery. There was no statistically significant reduction in corneal endothelial cell count up to 3 months after surgery (P=0.11).

The only complication was persistent subconjunctival TA deposit in one case of needling up to 3 months after surgery (Figure 2), with no other consequences. In this eye, IOP was effectively reduced from 26 mmHg preoperatively to 16 mmHg at 3 months, whereas the number of glaucoma drugs was reduced from 3 to 0. There was no incident of TA suspension entering anterior chamber. There were also no bleb infection, no conjunctival ulceration, and no observable cataract progression in those phakic-operated eyes.

Figure 2
figure 2

Subconjunctival deposit of white TA powder persisted in one eye for up to 3 months after surgery, but no adverse clinical effects had arisen.

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Comments

Giangiacomo et al5 previously described preoperative subconjunctival TA injection for trabeculectomy. However, they did not employ a standardized timing or dosage for the TA injection. As there is no evidence that injecting TA at 2 days to 1 week before surgery offers additional benefits, we believe our approach of TA injection at conclusion of surgery may be more convenient, and the operative site can be more accurately targeted.

Sterile conjunctival ulceration following subconjunctival TA injection has been reported.6, 7 Exact mechanism was unclear, but underlying autoimmune disease,7 an anterior interpalpebral injection site,6 a dose-dependent toxicity, and a bad batch of triamcinolone6 were proposed as possible causes. Our patients did not have known autoimmune diseases, and our injection site was not exposed in the interpalpebral space. Furthermore, our dosage of TA (1.2 mg) was substantially lower than the dosages routinely used for chronic uveitis (20–40 mg). For these reasons, we believe the risk of conjunctival ulceration associated with our approach should be minimal, although the present series may be too small to address this risk.

In conclusion, intrableb TA injection in bleb-forming filtration surgery is compatible with a desirable clinical outcome, and appears to be safe up to 3 months after surgery. We are evaluating whether intrableb TA injection will offer filtration patients additional clinical benefits when compared to patients receiving topical steroid only, in a randomized controlled trial.