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Traumatic expulsive aniridia after phacoemulsification

Prabhu, Avinash FRCS; Nayak, Harish FRCS; Palimar, Prasad FRCS

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Indian Journal of Ophthalmology: May–Jun 2007 - Volume 55 - Issue 3 - p 232-233
doi: 10.4103/0301-4738.31952
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Abstract

Cataract extraction with intraocular lens (IOL) implantation is the commonest sight restoring surgery performed in the elderly. Blunt trauma in these eyes can have serious consequences.12 However, with the change in cataract surgery to phacoemulsification and foldable lenses, available literature3456 experience suggest that these eyes suffer far less damage after blunt trauma. We describe a case of blunt ocular trauma following phacoemulsification leading to traumatic aniridia.

Case Report

A 79-year-old woman underwent uneventful phacoemulsification in left eye through a self-sealing 3.2 mm supero-temporal clear corneal incision. A foldable IOL (Acrysof MA 60 BM) was implanted by extending the wound to 4.1 mm. Preoperatively, the visual acuity was 20/120p with dry age related macular degenerative changes in both eyes. She was seen two weeks after surgery when the best corrected visual acuity was 20/60. One month following the surgery, the patient fell while getting out of her car, with the left side of her face hitting the curb. She experienced severe pain with immediate loss of vision in the left eye. She presented within 2 hours of trauma. The visual acuity was perception of light. There was full chamber hyphema and the intraocular pressure was 50 mmHg. A small tag of iris tissue was seen prolapsed from the corneal wound. An ultrasound B Scan of the left eye was normal. An X-ray of the skull and orbit showed no fractures. The right eye was normal.

The patient was administered 20% mannitol, 5 mL/kg intravenously followed by exploratory surgery and evacuation of the hyphema. Prolapsed iris tissue was abscised. There was no iris tissue present in the anterior chamber. The IOL remained well-centered in the bag and the zonules were intact. The corneal wound did not reveal any extensions. Though the wound was self-sealing, it was secured with three 10-0 nylon interrupted sutures [Fig. 1]. The patient was treated with a tapering dose of topical steroids and antibiotics. The eye settled down uneventfully and, by three months, the best-corrected visual acuity was 20/60. There was complete aniridia with visible ciliary processes and an intact capsular bag with a stable IOL. A detailed retinal examination was normal and the intraocular pressure was 15 mmHg. She has since undergone successful phacoemulsification surgery with IOL implantation in the right eye. She has been able to tolerate the glare in the left eye and has declined a colored contact lens.

Figure 1
Figure 1:
Aniridia with well-centered acrysof implant, one week following trauma

Discussion

Blunt ocular trauma causing complete iridodialysis is usually associated with severe structural damage to the globe with globe rupture, lens dislocation, vitreous hemorrhage, and retinal detachment in a normal eye. Globe rupture usually occurs at the limbus or at the insertion of the rectus muscles.1

In a study of ocular trauma in eyes with large incision extra capsular cataract extraction with 10/0 nylon sutures, wound rupture occurred in 86% of cases with IOL extrusion through the operative wound in 68% of cases.2 With the advent of phacoemulsification, available literature and experience show that the effects of blunt ocular trauma are milder with a more favorable course. Navon3 first reported expulsion of iris through 5´ 3.5 mm corneoscleral phacoemulsification wound following blunt trauma. In this case, complete iridodialysis occurred and iris tissue was seen in the scleral tunnel, which had opened but not extended. The IOL and capsular bag remained intact. Exploratory surgery was performed and the prolapsed iris was excised with evacuation of the hyphema. The vision was 20/40 uncorrected at 3 months. Lim4 noted a similar case of retention of iris tissue in a 5.2 mm self-sealing scleral wound in a post-operative eye following blunt ocular trauma.

Sullivan5 reported the long-term results of blunt trauma in an eye that had sutureless phacoemulsification through a 3.5 mm superior clear corneal incision. There was complete iridodialysis with the iris tissue retained in the anterior chamber. The iris tissue underwent complete absorption by necrosis. The IOL was seen in the bag and other ocular structures were unharmed. Ball6 noted total loss of iris tissue through a temporal clear corneal incision of 4´2 mm, with intact IOL in the bag without extension of the wound and the patient was managed conservatively.

The probable mechanism of injury in all these cases, including ours, is transient distortion of the wound due to flow of aqueous with high velocity across the wound. This rapid flow creates a relative vacuum anterior to the iris by the Bernoulli principle. The pressure gradient between the anterior and posterior surface of the iris results in prolapse of the iris, possibly a localized iridodialysis and plugging of the wound. The sudden block in aqueous flow creates a high-pressure gradient across the tunnel. This causes the extension of the localized iridodialysis into a complete one and delivery of the iris through the wound.7

Despite a complete iridodialysis in cases with a superior tunnel, some or all of the iris tissue was retained in the anterior chamber or the tunnel. We could speculate that the presence of the upper lid may have prevented a complete expulsion of the iris as opposed to the case reported by Ball in which the incision was located temporally. From cases reported so far, the small corneal or scleral tunnels may function as a release valve preventing severe structural damage to the eye compared to sutured wounds in extra capsular extractions.

We are not aware of similar cases reported after cataract surgery through non-phaco self-sealing cataract incisions. Shrinking corneal tunnel sizes with advent of cool phaco and rolled IOL implants may yet again change the way postoperative eyes behave when subjected to blunt trauma.

1. Duke ES Textbook of Ophthalmology Vol VI: Injuries. 1954 St Louis MO, Mosby:108–9
2. Assia EI, Blotnick CA, Powers TP, Legler UF, Apple DJ. Clinicopathological study of ocular trauma in eyes with intraocular lenses Am J Ophthalmol. 1994;117:30–6
3. Navon SE. Expulsive Iridodialysis: An isolated injury after phacoemulsification J Cataract Refractive Surg. 1997;23:805–7
4. Lim JI, Nahl A, Johnston R, Jarus G. Traumatic total iridectomy due to iris0 extrusion through a self-sealing cataract incision Arch Ophthalmol. 1999;117:542–3
5. Sullivan CA, Murray A, McDonnel P. The long-term results of nonexpulsive total iridodialysis: An isolated injury after phacoemulsification Eye. 2004;18:534–6
6. Ball J, Caesar R, Choudhuri D. Mystery of vanishing iris0 J Cataract Refract Surg. 2002;28:180–1
7. Allan BD. Mechanism of Iris0 Prolapse: A quantitative analysis and implications for surgical techniques J Cataract Refract Surg. 1995;21:182–6
Keywords:

Blunt trauma; expulsive; aniridia; phacoemulsificaiton

© 2007 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow