Quick Hit: Traumatic Lens Dislocation

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History of present illness

The patient is a male in his 50s with no significant past medical history who presented to the emergency department (ED) via ambulance after an assault. He was involved in an altercation with his fiancée and reports being struck in the head with a baseball bat. He is unsure if he lost consciousness but complains of severe pain on the back of his head, left side of his face, and in his left eye. His initial Glasgow Coma Scale was 15 per paramedic report. He denies photophobia, visual changes, nausea or vomiting. Of note, the patient reports a history of a traumatic cataract and subsequent cataract surgery in the left eye with unilateral loss of vision. 

physical exam

The patient is an intoxicated but well-appearing gentleman in no acute distress. He has two linear lacerations on the left and right aspects of his posterior scalp. There is left-sided periorbital edema with subconjunctival hemorrhage and significant chemosis of the left eye. Extraocular movements are intact and his pupils are reactive, 3 mm to 2 mm, bilaterally. There is no afferent pupillary defect. Visual acuity is 20/100 on the right and hand movements only on the left. Intraocular pressure is normal bilaterally. He has a normal neck exam without midline or bony tenderness. He is awake, alert, and oriented x4 with a normal neurologic exam. He has no other evidence of trauma and the remainder of his examination is within normal limits. 

Figure 1. Left lens dislocation.

imaging

CT scan of the head, face, and cervical spine demonstrate a left lens dislocation with pre-septal soft tissue swelling surrounding the left globe and overlying the left maxilla without underlying fracture. 

hospital course

While in the ED, the patient was treated with pain medication, tetanus immunization, and repair of his scalp lacerations. Ophthalmology was consulted and evaluated him in the ED. They recommended discharge with prednisolone and tropicamide eye drops and bacitracin-polymixin B ointment in the affected eye. Close follow-up was established in clinic in 48 hours. 

At the patient’s follow-up appointment with ophthalmology, his visual acuity had improved and was only slightly diminished from baseline in the affected eye. He was advised to follow-up with a retina specialist in 3-4 weeks for surgical planning. He ultimately underwent a pars plana vitrectomy with lens removal and placement of a new intraocular lens.

discussion

Traumatic lens dislocation is an uncommon sequelae of traumatic eye injuries. However, it has important sight-threatening complications and its recognition by ED providers is crucial. Eye complaints account for approximately 3-6% of ED visits, with traumatic injuries accounting for the vast majority of problems for which patients seek treatment.[1] Ectopia lentis is the dislocation or disruption of the natural crystalline lens from the zonule fibers, or fibrous connective tissue bands that connect the lens to the ciliary body. Complete disruption of these zonule fibers results in dislocation of the lens. The dislocated lens may lie in the anterior chamber, vitreous, or directly on the retina. When the zonule fibers are incompletely disrupted, the lens is subluxed, or partially displaced but still remains within the lens space.[2,3]

Although lens dislocation occurs infrequently after blunt eye trauma, trauma is the most common cause of lens dislocation. Blunt force in the anteroposterior direction leads to equatorial expansion, which in turn disrupts the zonular fibers. Traumatic lens dislocation (TLD) often occurs after a direct blow to the eye, as with a baseball or golf ball, or after blunt trauma to the head. It has also been associated with airbag injuries.[1,4] Patients with prior ophthalmologic surgery or connective tissue disorders often have weakness of the zonule fibers and are at increased risk for lens dislocation even after minor trauma. Certain conditions such as retinitis pigmentosa, homocystinuria, Marfan syndrome, Ehlers-Danlos, and tertiary syphilis are also associated with lens dislocation. Up to 75% of patients with Marfan syndrome and 90% of patients with homocystinuria will develop ectopia lentis. Therefore, providers should retain a high suspicion in patients with visual complaints  and the appropriate medical history.[2] For example, the patient presented above had both a predisposition due to his prior cataract surgery, and a concerning mechanism of injury to suggest this diagnosis. 
 
Symptoms of ectopia lentis include monocular diplopia and visual distortion. Symptoms vary based on the extent of displacement, but complete displacement may result in marked visual blurring. As with the above patient, presence of specific risk factors should raise suspicion for this condition. As with any traumatic mechanism, the patient should be evaluated for additional injuries, including an appropriate and thorough evaluation for an open globe. 

Exam findings include decreased visual acuity in the affected eye. The edge of the subluxed or dislocated lens may be visualized on slit lamp exam when the pupil is dilated. In the setting of lens dislocation, the patient may have trembling or shimmering of either the lens or iris, phakodenesis or iridodonesis, respectively. Iridodonesis, while not pathognomonic for ectopia lentis, usually results from disruption or absence of the crystalline lens.[3,5]

This diagnosis is often discovered or confirmed on CT scan. In addition, bedside ocular ultrasound can expedite the diagnosis of lens subluxation and dislocation in the ED. It can prompt ophthalmologic consultation without, or prior to, completion of the CT scan. There have been multiple case reports of accurate diagnoses of a dislocated or subluxed lens via ultrasound in the ED. In settings without ready access to a CT scanner such as rural departments or resource poor settings abroad, ultrasound may serve as an alternative means of making an accurate diagnosis of ectopia lentis. Ultrasound can also assist visualization of the posterior structures of  the eye when the view is obscured by cataract or hemorrhage.[3,6,7,8] One study has shown bedside ultrasound to have 84.6% sensitivity, 98.3% specificity, and accuracy of 96.9% when compared to orbital CT.[9]

Management of a traumatic lens dislocation or subluxation is challenging even for ophthalmologists and anterior chamber sub-specialists. The tenants of management in the ED are to first complete a thorough history and examination to assess for evidence of concomitant trauma and open globe. Patient stabilization and treatment of other injuries should be prioritized. Pain control should also be pursued. Lens dislocation or subluxation has the potential to lead to increased intraocular pressure via recession of the angle and zonular fibers. Consequently, early measurement of intra-ocular pressures is key. The patient may also sustain posterior chamber trauma, such as retinal tears, breaks, or tufts. Therefore, once stable, emergent ophthalmologic consultation is warranted. 

Occasionally, dislocated lenses may relocate without intervention. Medical options for management include administering mydriatic agents with or without external manipulation on the lens. Nonetheless, many will require surgical removal of the displaced lens and implantation of an artificial lens.[2] In the end, the priority for ED providers should be recognition of a lens dislocation and early involvement of an ophthalmologist for definitive treatment. 

authored by kelli jarrell, mD

Posted by Matthew Scanlon, md

references

  1. Netland KE, Martinex J, LaCour, OJ, Netland PA. Traumatic anterior lens dislocation: A Case Report. The Journal of Emergency Medicine. 1999; 17:4, 637-9.
  2. Bjerregaard R, Ringeisen A. Ectopia Lentis. In: Lombardi L, eds. EyeWiki. American Academy of Ophthalmology; 2015. http://eyewiki.aao.org/Ectopia_Lentis. Accessed 02 May 2017. 
  3. Nickson C. Bump and blur. In Nickson C, eds.  Life in the Fast Lane. 2010. https://lifeinthefastlane.com/ophthalmology-befuddler-029/. Accessed 02 May 2017. 
  4. Pearlman J, Au Eong KG, Kuhn F, and Pieramici D. Airbags and eye injuries: epidemiology, spectrum of injury, and analysis of risk factors. In Fong D and Seddon J, eds. Public Health and the Eye. Survey of Ophthalmology. 2001 46(3): 234-42.
  5. Mahadevan SV and Savitsky E. Emergency management of traumatic eye injuries. Trauma Reports. 01 July 2001. https://www.ahcmedia.com/articles/71714-emergency-management-of-traumatic-eye-injuries. Accessed 19 May 2017. 
  6. Lee S, Hayward A, Bellamkonda VR. Traumatic lens dislocation. International Journal of Emergency Medicine. 2015;8:16.
  7. Eken C, Yuruktumen A, and Gunay Y. Ultrasound diagnosis of traumatic lens dislocation. Journal of Emergency Medicine. 2013;44(1):e109-110. 
  8. Blaivas M, Theodoro D, Sierzensk P. A study of bedside ocular ultrasonography in the emergency department. Academic Emergency Medicine. 2002 9(8):791-9. 
  9. Haghighi S, Begi H, Sorkhabi R, Tarzamani M, Zonouz G, Mikaeilpour A, and Rhmani F. Diagnostic Accuracy of Ultrasound in Detection of Traumatic Lens Dislocation. Emergency (Tehran). 2014 Summer, 2(3): 121-124.