An Airbag Deploys, Leaving Vision Blurry and Distorted

Discussion

Airbags have dramatically reduced major injuries and deaths from motor vehicle accidents. Although most airbag-induced injuries are self-limited and do not significantly compromise vision, healthcare professionals need to be aware that they are not uncommon and can be serious. Most injuries are related to blunt trauma, but occasionally can be related to alkali burns from leaking airbag chemicals. Having appropriate triage and specialized care can maximize visual outcome and ensure appropriate treatment.^[1,2]

On the basis of the classification from the International Society of Ocular Trauma, our patient experienced a closed globe contusion injury in zone 2, located internal to the cornea and extending to the posterior lens capsule and pars plicata.^[3] The contusion injury involved the cornea, lens, and ciliary body, resulting in a corneal abrasion, traumatic cataract, and cyclodialysis cleft, respectively. Findings in zone 3, located in the macula and the peripheral retina, were secondary to the cyclodialysis cleft and hypotony, and not a direct result of the kinetic energy of the airbag.

Our patient's hypotony with maculopathy was secondary to the traumatic cyclodialysis cleft. A cyclodialysis cleft is a separation of the circumferential muscle of the ciliary body insertion from the scleral spur, which creates an abnormal conduit for aqueous humor to drain into the suprachoroidal space. This results in a low intraocular pressure or hypotony, the latter of which can cause changes to the entire eye and—when significant— induce hyperopia, shallowing of the anterior chamber, choroidal effusions, chorioretinal folds, and optic disc edema.

Cyclodialysis clefts most commonly occur after blunt eye trauma, as in our patient. Once an open-globe injury has been ruled out, a cyclodialysis cleft should be suspected in any eye that has experienced blunt trauma and presents with hypotony, iris sphincter tears, hyphema, and a shallow anterior chamber.

Besides resulting from trauma, cyclodialyses can also be iatrogenic. Historically, cyclodialysis clefts were intentionally created to treat glaucoma, but now also occur as a complication of intraocular surgeries involving manipulation of the iris, including cataract surgery and intraocular lens placement or exchange.

Diagnosis of a cyclodialysis cleft can be made on gonioscopic examination. The cleft appears as an abnormal region just posterior to the scleral spur. At the margin of the cyclodialysis, the ciliary body band can appear as a discontinuation with posterior displacement of the iris root and ciliary body. The color of the scleral side of the cleft can range from white to black, depending on how much uveal pigment remains on the internal surface of the sclera posterior to the scleral spur.^[4]Our patient's cyclodialysis cleft was diagnosed on gonioscopic examination and confirmed using high-frequency UBM, which can accurately diagnose cyclodialyses even in the presence of hazy media, hypotony, or abnormal anterior segment anatomy when gonioscopic view may not be possible.^[5]

Management of cyclodialysis clefts usually includes a stepwise approach, depending on the size of the cleft and its associated complications. The most common treatments include medical management, laser photocoagulation, transscleral diathermy, and surgical cyclopexy. Even though most cyclodialysis clefts close spontaneously or with conservative medical management, our patient's cleft did not. Despite the use of atropine sulphate 1% to relax the ciliary muscle and facilitate its apposition to the sclera, and the reduction of steroids to help promote closure, argon laser photocoagulation to the cleft was necessary. For large cyclodialysis clefts and those not amenable to laser treatment, surgical repair may be necessary.^[6]

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