Traumatic Cataract

Background

Traumatic cataracts occur secondary to blunt or penetrating ocular trauma. Infrared energy (glass-blower's cataract), electric shock, and ionizing radiation are other rare causes of traumatic cataracts.^[1]

Cataracts caused by blunt trauma classically form stellate- or rosette-shaped posterior axial opacities that may be stable or progressive, whereas penetrating trauma with disruption of the lens capsule forms cortical changes that may remain focal if small or may progress rapidly to total cortical opacification. Shah et al found that traumatic cataracts without globe rupture generally have a better prognosis for visual recovery after surgery, at least in children.^[2]

Note the images below.

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Classic rosette-shaped cataract in a 36-year-old man, 4 weeks after blunt ocular injury.

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Same cataract as seen in previous image, viewed by retroillumination.

See What the Eyes Tell You: 16 Abnormalities of the Lens, a Critical Images slideshow, to help recognize lens abnormalities that are clues to various conditions and diseases.

Lens dislocation and subluxation are commonly found in conjunction with traumatic cataract. Other associated complications include phacolytic, phacomorphic, pupillary block, and angle-recession glaucoma; phacoanaphylactic uveitis; retinal detachment; choroidal rupture; hyphema; retrobulbar hemorrhage; traumatic optic neuropathy; and globe rupture.^{[3, 4, 5]}

Traumatic cataract can present many medical and surgical challenges to the ophthalmologist. Careful examination and a management plan can simplify these difficult cases and provide the best possible outcome.^{[5, 6]}

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Pathophysiology

Blunt trauma is responsible for coup and contrecoup ocular injury. Coup is the mechanism of direct impact. It is responsible for Vossius ring (imprinted iris pigment) sometimes found on the anterior lens capsule following blunt injury. Contrecoup refers to distant injury caused by shockwaves traveling along the line of concussion.^[7]

When the anterior surface of the eye is struck bluntly, there is a rapid anterior-posterior shortening accompanied by equatorial expansion. This equatorial stretching can disrupt the lens capsule, zonules, or both. Combination of coup, contrecoup, and equatorial expansion is responsible for formation of traumatic cataract following blunt ocular injury.^{[8, 9, 10]}

Penetrating trauma that directly compromises the lens capsule leads to cortical opacification at the site of injury. If the rent is sufficiently large, the entire lens rapidly opacifies, but when small, cortical cataract can seal itself off and remain localized.

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Epidemiology

Frequency

United States

Approximately 2.5 million eye injuries occur annually in the United States. It is estimated that approximately 4-5% of a comprehensive ophthalmologist's patients are seen secondary to ocular injury. Traumatic cataract may present as acute, subacute, or late sequela of ocular trauma.

Mortality/Morbidity

Trauma is the leading cause of monocular blindness in people younger than 45 years. Annually, approximately 50,000 people are left unable to read newsprint as a result of ocular trauma. Only 85% patients who experience anterior segment injury reach a final visual acuity of 20/40 or better, whereas only 40% patients with posterior segment injury reach this level.^{[8, 9]}

Sex

The male-to-female ratio in cases of ocular trauma is 4:1.

Age

Work- and sports-related eye injuries most commonly occur in children and young adults. Between 1985-1991, a National Eye Trauma System study reported a median age of 28 years in 648 assault-related cases.

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Prognosis

The prognosis is dependent on the extent of the injury.

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Patient Education

Protective eyewear is important in high-risk activities to avoid injury. For patient education resources, see the Eye & Vision Center as well as Cataracts.

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History

Note the following:

• Mechanism of injury - Sharp versus blunt
• Past ocular history - Previous eye surgery, glaucoma, retinal detachment, diabetic eye disease
• Past medical history - Diabetes, sickle cell, Marfan syndrome, homocystinuria, hyperlysinemia, sulfate oxidase deficiency
• Visual complaints - Decreased vision (cataract, lens subluxation, lens dislocation, ruptured globe, traumatic optic neuropathy, vitreous hemorrhage, retinal detachment); monocular diplopia (lens subluxation with partial phakic and aphakic vision); binocular diplopia (traumatic nerve palsy, orbital fracture); pain (glaucoma secondary to hyphema, pupillary block, or lens particles; retrobulbar hemorrhage; iritis)

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Physical

Complete ophthalmic examination (defer in case of globe compromise), to include the following:

• Vision and pupils - Presence of afferent pupillary defect (APD) indicative of traumatic optic neuropathy
• Extraocular motility - Orbital fractures or traumatic nerve palsy
• Intraocular pressure - Secondary glaucoma, retrobulbar hemorrhage
• Anterior chamber - Hyphema, iritis, shallow chamber, iridodonesis, angle recession
• Lens - Subluxation, dislocation, capsular integrity (anterior and posterior), cataract (extent and type), swelling, phacodonesis
• Vitreous - Presence or absence of hemorrhage, posterior vitreous detachment
• Fundus - Retinal detachment, choroidal rupture, commotio retinae, preretinal hemorrhage, intraretinal hemorrhage, subretinal hemorrhage, optic nerve pallor, optic nerve avulsion

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Causes

Traumatic cataracts occur secondary to blunt or penetrating ocular trauma.

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Complications

Lens dislocation and subluxation are commonly found in conjunction with traumatic cataract.^[4]

Other associated complications include the following: phacolytic, phacomorphic, pupillary block, and angle-recession glaucoma; phacoanaphylactic uveitis; retinal detachment; choroidal rupture; hyphema; retrobulbar hemorrhage; traumatic optic neuropathy; and globe rupture.^[5]

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Imaging Studies

Perform the following:

• B-scan - If the posterior pole cannot be visualized
• A-scan - Prior to cataract extraction
• CT scan of the orbits - Fractures and foreign bodies^{[11, 12]}

Tabatabaei et al showed that 20-MHz ultrasound (Eye Cubed) was both more sensitive and more specific than anterior-segment optical coherence tomography (OCT; Visante model 1000) and Scheimpflug imaging (Pentacam) in detecting posterior capsular rupture prior to surgery in patients with traumatic cataract.^[13] ​

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Medical Care

If glaucoma is a problem, control intraocular pressure with standard medications. Add corticosteroids if lens particles are the cause or if iritis is present.

For focal cataract, observation is warranted if the cataract is outside the visual axis. Miotic therapy may be of benefit if the cataract is close to the visual axis.

In some cases of lens subluxation, miotics may correct monocular diplopia. Mydriatics may allow for vision around the lens with aphakic correction.

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Surgical Care

Planning the surgical approach is of the utmost importance in cases of traumatic cataract. Preoperative capsular integrity and zonular stability should be surmised.

In cases of posterior dislocation without glaucoma, inflammation, or visual obstruction, surgery may be avoided.

Indications for surgery include the following:

• Unacceptable decreased vision
• Obstructed view of posterior pathology
• Lens-induced inflammation or glaucoma
• Capsular rupture with lens swelling
• Other trauma-induced ocular pathology necessitating surgery

Standard phacoemulsification may be performed if the lens capsule is intact and sufficient zonular support remains.

Intracapsular cataract extraction is required in cases of anterior dislocation or extreme zonular instability. Anterior dislocation of the lens into the anterior chamber requires emergency surgery for its removal, as it can cause pupillary block glaucoma.

Shah et al demonstrated that, as part of the primary procedure for traumatic cataract, posterior capsulectomy and anterior vitrectomy improve visual outcomes.^[14] According to Trivedi and Wilson, primary posterior capsulectomy and vitrectomy should be considered irrespective of age in children undergoing surgery for traumatic cataract.^[15]

Pars plana lensectomy and vitrectomy may be best in cases of posterior capsular rupture, posterior dislocation, or extreme zonular instability.

Automated irrigation/aspiration can be used in patients younger than 35 years.

Lens implantation^[16] is as follows:

• Capsular fixation is the preferred placement if the lens capsule and zonular support are intact.
• Polymethyl methacrylate (PMMA) capsular tension rings allow capsular fixation in cases of zonular dialysis less than 180 degrees.
• Sulcus fixation is safe if the posterior capsule is compromised but zonular support is maintained.^[17]
• Suture fixation is chosen if both capsular and zonular supports are insufficient and the angle is minimally damaged.
• Anterior chamber placement is an option if no posterior support remains and iris or ciliary body trauma prevents suture fixation.
• Aphakia may be a better choice in young children and in patients with highly inflamed eyes, as they may experience better outcomes if lens implantation is deferred.^[18]

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Consultations

Vitreoretinal consultation is necessary if a pars plana approach is mandated and the surgeon is untrained in posterior segment surgery.

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Prevention

Protective eyewear should be worn when participating in any high-risk activities. Most serious eye trauma can be avoided if proper eye and face protectors are used.

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Long-Term Monitoring

Patients should receive follow-up care as needed.

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