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Sir,

Small self-sealing incisions in phacoemulsification cataract surgery confer great incision strength and stability in vivo.1,2 Isolated traumatic aniridia is extremely rare. The presented case is a non-expulsive total iris avulsion and complete iris absorption. To our knowledge this is the first case reported. The long-term sequelae of this patient and the biomechanics of self-sealing incisions are discussed.

Case report

A 79-year-old Caucasian woman presented having fallen and struck her right eye against a toilet seat. Eight weeks earlier she had undergone an uncomplicated right sutureless phacoemulsification cataract extraction through a 3.5–4.0 mm superior incision, and insertion of a silicone folding intracapsular intraocular lens (IOL). Prior to the fall her right visual acuity was 6/9 unaided.

On examination, the anterior chamber was well formed and the corneal incision intact. She had a complete hyphaema with dense material inferiorly. Her best-corrected visual acuities (BCVAs) were perception of light in the right and 6/12 in the left, intraocular pressures 48 in the right and 12 in the left; the globe was intact.

The patient was treated with systemic carbonic anhydrase inhibitors, topical steroids, and topical glaucoma medication. Six days post-trauma it was apparent that she had suffered a 360° iridodialysis, and the dense material inferiorly was rolled up iris. The IOL was in situ and stable within the capsular bag. The avulsed iris gradually shrunk in size accompanied by increased anterior chamber cells and eventually disappeared 4 weeks post-trauma, leaving the patient aniridic. Iris absorption was accompanied by episodic elevations of intraocular pressure. Eight weeks post-trauma the hyphaema had completely resolved and the intraocular pressure settled at 14–18 mmHg without medication (Figure 1).

Figure 1
figure 1

Silicone intraocular lens within intact capsule and traumatic aniridia.

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The patient's (BCVA) improved to 6/9 in the right eye. However, she experienced glare and refrained from driving.

Over the following 4 years there was opacification and phimosis of the capsule resulting in an excellent cosmetic pseudo-pupil with pseudoiris (Figure 2). Following posterior Yag capsulotomy her visual acuity is 6/9 unaided.

Figure 2
figure 2

Cosmetic appearance of opacified capsule.

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Despite aniridia the intraocular pressures remain normal, 16 mmHg in both eyes without medication, and normal grade 4 angles. The IOL remains stable and there is no zonular dehiscence.

Comment

Navon,3 Ball4 and Rossa5 have all reported cases of blunt trauma and expulsive iridodialysis following phacoemulsification surgery. This case shares similar characteristics, the disinsertion was at the iris root, and the capsular bag was completely unharmed. The proposed mechanism of injury is that (1) the force of the trauma transiently distorted the cataract incision, causing it to leak. (2) Aqueous outflow created a lifting action over the iris and drew it to plug the wound by the Bernoulli effect.6 (3) The sudden block in aqueous flow created a pressure gradient across the tunnel sufficient to disinsert the iris at its thinnest and weakest point, the root. (4) Outflow of aqueous depressurised the eye, which prevented extension of the wound or creation of new rupture sites. (5) The chamber reformed by the self-sealing properties of the wound, and the disinserted iris settled in the inferior anterior chamber.

To our knowledge this is the first published case of nonexpulsive isolated aniridia. The absorption probably resulted from iris necrosis. Publications have recommended surgical removal of iris in subtotal iridodialysis, to avoid secondary glaucoma from necrotic inflammation.7 In this case, surgery was avoided. The aniridia caused debilitating glare, but resolved with capsule opacification.

This is a very rare case; it implies that necrotic iris absorption can be treated safely with topical steroids. In addition, the mechanism of developing glaucoma in traumatic pseudophacic aniridia is different from traumatic-phacic aniridia and congenital aniridia.