Traumatic Cataract Surgery

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 by Anna Murchison, MD, MPH on June 9, 2021.


Disease Entity

Epidemiology

Both penetrating and blunt ocular injuries can result in development of cataracts. There is approximately a 14% lifetime prevalence of ocular trauma in the general population, and it disproportionately affects children and young men. [1][2][3] Mechanisms of ocular injury vary by urban versus rural settings, region of the world, and patient age.[2] [4][5][6][7][8] Depending on the report, 27-65% of ocular traumas lead to cataracts.[9][10] The majority of traumatic cataracts are visually significant and require surgery.[10] Even in cases without visually significant cataract, subluxation of the lens can occur due to zonular damage and prompt the need for surgical intervention.[9]  Traumatic cataracts are often accompanied by damage to other ocular structures, and they pose a significant public health burden in that they disproportionately affect young people and cause disability if not managed appropriately.[2][3][4][5][11] Safety measures to prevent traumatic cataracts should be tailored to local communities, as mechanisms of ocular injury vary by environment.

Pathophysiology

Cataracts may form immediately after trauma or months to years later.  Rapid cataract formation is typically a result of lens capsule rupture with seepage of aqueous humor into lens fibers.2 If there is no capsule rupture, it is suspected that the traumatic forces damage lens fibers, ultimately resulting in cataract formation.2

Diagnosis and Surgical Planning

Pertinent Patient History

  • Age of patient:  Pediatric patients with traumatic cataracts are at risk for developing amblyopia.[6] Additionally, children may not be reliable historians when recounting their ocular trauma, so suspicion for globe rupture or an intraocular foreign body should remain high.
  • Mechanism of injury: It is important to determine whether the injury was penetrating or blunt, and if an intraocular foreign body may be involved in order to decide whether additional imaging is needed and to plan surgery.
  • Timeline of injury: Formation of cataract minutes to hours after an ocular trauma should raise suspicion for violation of the anterior lens capsule.[12]
  • Patient’s ocular history: This may help estimate a patient’s visual potential. In addition, it is important to be aware of any prior intraocular surgeries for surgical planning of cataract extraction.
  • Patient’s systemic comorbidities: Diabetes and immunocompromising conditions may increase risk of infection with ocular trauma and cataract surgery.[12] Patients’ medication history should be reviewed, including use of tamsulosin and anticoagulation, and their last tetanus booster.

Exam Signs

  • Birmingham Eye Trauma Terminology (BETT): The BETT system was developed as a standardized method for documenting ocular trauma.[13][14][15] Notably there is no standardized system for describing traumatic cataracts.[16]
  • Visual acuity: Pre-operative visual acuity helps predict best corrected visual acuity after removal of the traumatic cataract.[17][18]
  • Intraocular pressure (IOP):  An asymmetrically low IOP may indicate an open globe injury or a cyclodialysis cleft.[11] An elevated IOP may reflect lens-associated glaucoma (phacomorphic, lens particle, or phaco-antigenic), hyphema, orbital compartment syndrome (in the acute trauma setting), or angle recession glaucoma (in the chronic post-traumatic setting).
  • Pupils: The presence of a relative afferent pupillary defect (rAPD) can occur with traumatic optic neuropathy or optic nerve avulsion and help prognosticate a patient’s visual potential after cataract removal.[17] Importantly, a cataract alone does not cause an rAPD.
  • Cornea: Severe corneal damage and haze may limit pre-operative assessment of cataract, make intraocular lens (IOL) power calculation challenging, and cause poor intraoperative visualization. If IOL calculations cannot be performed, IOL placement may be deferred or may be calculated based on the uninjured fellow eye.[12][16] Some patients with severe corneal scarring may require use of a hard contact lens after cataract surgery, in which case the precision of IOL calculations is not as critical.
  • Anterior chamber: Flattening of the anterior chamber may indicate rupture or a self-sealed laceration. Assess the anterior chamber for hyphema, lens material, inflammatory reaction, or vitreous prolapse.
  • Iridocorneal angle: Evaluate for narrowing or occlusion of the iridocorneal angle secondary to lens swelling or displacement. If there is no concern for globe rupture, use gonioscopy to evaluate the angle.
  • Iris: Transillumination defects may indicate intraocular foreign body or iris disinsertion.  Iris injury often occurs concomitantly with traumatic cataract.
  • Lens: Although there is no standardized system for documenting traumatic cataract features, it is important to characterize location of the lens opacity (central vs. peripheral), severity, and morphology of the cataract (membranous, rosette, soft fluffy, or total).[11][16][19]  Classically, traumatic cataracts have a rosette or stellate appearance.[12] It is also important to note lens position, presence of phacodonesis, and anterior capsule rupture. These features help confirm whether there is zonular injury and determine the urgency of performing cataract extraction.
  • Posterior segment: If the view of the posterior segment is obscured, obtain gentle B-scan ultrasonography to confirm a normal globe contour and assess for intraocular foreign bodies, vitreous opacities, retinal detachments, or choroidal ruptures. In unpublished data from the United States Eye Injury Registry, 48% of eyes with traumatic cataract were also found to have injury to the posterior segment.[20]
  • Additional imaging: A CT scan may help rule out an intraocular or intraorbital foreign body and abnormal globe contour. Ultrasound biomicroscopy helps evaluate the posterior capsule, lens position, iridocorneal angle, and integrity of the zonules.

Management

Primary Versus Secondary Cataract Extraction

Cataract extraction may be performed immediately following open globe trauma as a “primary” procedure or deferred weeks to months after the trauma as a “secondary” procedure. Removal of the traumatic cataract should be performed urgently if there is capsule rupture, lens material in the anterior chamber, phacomorphic glaucoma, or any other conditions placing the patient at high risk for developing inflammation and increased intraocular pressure. If none of these conditions are present, deferring surgery may be considered.

There is no consensus on optimal timing of cataract extraction for traumatic cataracts.[9]  Benefits of secondary extraction include the potential for more accurate intraocular lens calculation, improved visualization during surgery, and operating in a “quiet” eye.[21][22] In contrast, proposed advantages of primary extraction include lower cost and time of a single surgery or hospital admission, minimizing risk of developing elevated IOP and synechia, and decreasing visual rehabilitation time and risk of amblyopia.[20]

In addition to timing of cataract extraction, IOL placement may be a primary procedure performed at the time of cataract extraction or a secondary procedure performed at a later date. Most adult patients undergo primary IOL placement[16] and in pediatric cases, primary cataract extraction and IOL placement help minimize risk of amblyopia.[20] One reason to perform secondary IOL placement is if a patient has peripheral vitreoretinopathy and may require a vitrectomy. Visualization of the peripheral retina for these cases may be more difficult with an IOL in place.[20] Additionally, in open globe injuries with primary cataract extraction occurring at the same time as globe repair surgery, many surgeons will defer IOL placement given the increased risk for endophthalmitis associated with open globe trauma.[23]

Surgical Techniques

Integrity of the anterior capsule: Using trypan blue intraoperatively helps identify tears in the anterior capsule.[12][24] There should be high suspicion for capsule rupture if the lens opacified minutes to hours after the trauma.[12] When there is concern for a capsule tear, hydrodissection should be used sparingly and cautiously to avoid worsening the tear.[11]

Zonular damage: If there is zonular weakness or damage, iris hooks or capsular bag hooks may help hold the bag open during cataract extraction.[12] If there are 30-90 degrees of zonular dialysis, capsular tension rings may be used, although they are contraindicated if there is a posterior capsule rupture or no continuous curvilinear capsulorhexis.[12]

Iris management: Synechiae are fibrinous adhesions which form in the setting of inflammation and can scar the iris down to adjacent structures and impair dilation. These synechiae may need to be lysed (i.e. synechiolysis) at the time of cataract surgery if they interfere with visualization of the lens. Iris hooks or a Malyugin ring can be used intraoperatively to dilate the iris after synechiae are lysed. If there is iridodialysis, the iris itself may require repair.[11]

Phacoemulsification: Low and gentle phacoemulsification settings should be used for traumatic cataract extraction.[12] Specific settings vary by phaco machine.

Cataract morphology: Cataract morphology and the extent of damage of other ocular tissues help determine surgical planning and technique:

  • Cataracts with a hard nucleus: typically use phacoemulsification.[11]
  • White soft or rosette cataracts: typically use unimanual or bimanual aspiration.[11]
  • Membranous cataracts: often require membranectomy and anterior vitrectomy.[11][19]

Intraocular lens: Typically if the capsular bag is intact, a 1-piece acrylic IOL is placed in the bag.[12] In the case of a ruptured posterior capsule and intact anterior capsule, a 3-piece acrylic IOL should be placed in either the capsular bag or ciliary sulcus.[12] If there is no capsular support, a scleral-fixated IOL may be required. See above for discussion of primary versus secondary IOL placement.

Intraoperative Complications

As with non-traumatic cataract extraction, intraoperative complications include capsular violation, zonular dehiscence, vitreous prolapse, and hyphema. Anterior vitrectomy should be performed if there is vitreous prolapse, and an anterior chamber washout should be performed if there is a hyphema to prevent blood staining of the cornea.[12]

Postoperative Management

As with non-traumatic cataract surgery, most surgeons perform follow-up examinations on post-operative day 1, week 1, and month 1. Patients should complete a course of topical antibiotic and anti-inflammatory eye drops. If complications arise, patients should be followed more closely with steroid eye drops adjusted appropriately and IOP lowering drops started as needed.

Pediatric Considerations

Children are disproportionately affected by ocular trauma, and there are several special considerations for managing pediatric traumatic cataracts.

  • Pre-operative: There is a lower threshold for classifying a cataract as visually significant in pediatrics as compared to adults. Children are at risk for amblyopia with even small opacities in their central visual axis, and it has been suggested that the same threshold for removing a congenital cataract be used for traumatic cataracts.[10] This means a lens with an opacity greater than 3mm in the visual axis should be removed. Additionally, cataract extraction should be performed as a primary procedure urgently because delay increases risk of amblyopia.
  • Intraoperative: For children less than 2 years old, pars plana vitrectomy is often performed with cataract extraction. In this same age group, IOL placement is often deferred and performed as a secondary procedure.[11]
  • Post-operative: Pediatric patients are at risk for amblyopia, and they may benefit from patching of their good eye in post-operative visual rehabilitation if indicated.7 Posterior capsular opacification is a common postoperative complication for pediatric patients, and if undetected may also result in amblyopia.[7][8] Young patients are also at risk for fibrinous uveitis due to exuberant inflammatory responses and may require aggressive pre and post-operative control of inflammation with steroids.[8]

Prognosis

Several factors have been identified to predict visual outcome in patients with traumatic cataracts. A prognostication tool, the Ocular Trauma Score (OTS), was developed in the early 2000s to predict visual outcomes after ocular trauma. It includes the following factors to make predictions about visual acuity: initial vision, presence of rupture, endophthalmitis, perforating injury, retinal detachment, and afferent pupillary defect.[17][18] A retrospective study of over 300 children demonstrated OTS reliably predicts visual outcomes in pediatric patients with traumatic cataracts.[18][25]

Morphology of cataract has also been shown to affect surgical technique and visual outcome.[19] There is conflicting data on whether penetrating versus blunt traumas have better outcomes.[8] [25][26][27][28] Similarly, there is no consensus on whether primary versus secondary cataract extraction is optimal.

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