Sir,

We report the case of a patient who suffered blunt trauma a month after trabeculectomy with mitomycin C (MMC), resulting in traumatic aniridia.

Case report

A 60-year-old Caucasian man underwent successful trabeculectomy in his right eye for advanced glaucoma with 0.4% MMC. After 1 month, his visual acuity (VA) remained stable at 6/36 (OD) and 6/6 (OS) with a functioning bleb and intraocular pressure (IOP) of 17 mm Hg compared with 24 mm Hg preoperatively.

A few days later, he suffered a blunt trauma with a metal tool falling and hitting his right eye. His VA was ‘hand movements’ with an IOP of 18 mm Hg in his right eye. There was complete absence of his iris and brown pigmented tissue was found beneath the bleb extending superonasally. There was a 1-mm hyphaema but no leak, with deep anterior chamber, stable lens, and no posterior segment involvement.

Perioperatively, the entire iris had prolapsed and plugged the scleral flap spreading from the superior rectus to the medial rectus, underneath sub-Tenon’s layer (Figure 1a). The scleral flap sutures remained intact (Figure 1b). The prolapsed iris was excised and another flap suture was added with watertight conjunctival closure.

Figure 1
figure 1

Anterior segment photograph showing prolapsed iris tissue superiorly through trabeculectomy scleral flap wound (a), resulting in aniridia with an intact capsular bag and lens held by zonular fibres (b).

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After 3 months, the bleb was failing with a flat, vascularised appearance but vision was stable at 6/36 (OD) and an IOP of 14 mm Hg with three glaucoma medications (Figure 2).

Figure 2
figure 2

Anterior segment photograph showing post-operative appearance after several months with scleral flap wound and residual iris pigments (a) as well as established aniridia (b).

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Comment

Although several reports of aniridia following blunt injury after cataract surgery exist,1, 2 as far as we know the effect of trauma on eyes following trabeculectomy has not been reported extensively.3 To our knowledge, there is only one other report of traumatic aniridia following trabeculectomy, but the eye had undergone two previous trabeculectomies and cataract surgery.4

Blunt trauma causes globe distortion and an acute rise in IOP, leading to iris root rupture. Aqueous fluid leaks through the scleral wound that acts as a decompression valve, preventing further rupture but allowing the aqueous flow to pull the disrupted iris forward to plug the bleb wound.2, 5 It is likely that the use of MMC and the unusual nature of the injury in this case are other aiding factors. As with other reports, the lens and capsule were able to withstand these forces and remain stable.