• 4 SECTION Trauma

Radiation-induced Cataract

Key Facts

•The lens is the most radiosensitive ocular structure • Most susceptible if less than 1 year of age

•Radiation damages tumor DNA as well as cell membranes, causing germinative lens epithelial cells to swell, migrate posteriorly, and form posterior polar subcapsular cataract in 22–87% of eyes

•Stationary or progressive

•Latency period: months to years

•Four stages:

1.posterior sutural opacities (caused by posterior migration of lens epithelial cells)

2.a yellow-gold chromatic iridescence at the posterior pole (also caused by the extension of epithelium toward the posterior pole)

3.stone-like opacities at the posterior pole

4.immature cataract (secondary degeneration and liquefaction of posterior lens cortex)

Clinical Findings

•Posterior subcapsular cataracts more than anterior subcapsular cataracts

•Disc-like zone of opacification at equator and posterior pole

•Subcapsular vacuoles

•Liquefaction

Ancillary Testing

•Careful ocular examination to rule out radiation retinopathy, radiation keratitis, or optic neuropathy

Differential Diagnosis

• Posterior subcapsular cataract, diabetes

Treatment

•Lensectomy if visually significant

•Because there is increased risk of posterior capsular disruption with advanced plaque-like posterior capsular cataracts, surgeons should err on the side of caution when performing hydrodissection

•It is also important to polish the posterior capsule during phacoemulsification of mild posterior capsular cataracts to minimize the incidence of postoperative posterior capsular opacification

•It may not be safe to polish the capsule of advanced posterior capsular cataracts, which sometimes necessitates YAG capsulotomy at a later date

Prognosis

• Dependent on retinal, tear function, and optic nerve status

Fig. 4.7 Posterior subcapsular plaque after radiation therapy for cancer.

Fig. 4.8 A posterior subcapsular cataract affecting the central visual axis in another patient who had radiation therapy.

Fig. 4.9 A more diffuse subcapsular cataract in a 55-year- old man after radiation treatment.

Cataract induced-Radiation

• 4 SECTION Trauma

Electric Shock Cataract

Key Facts

•Cataract is the most common change following electric shock

•Can occur after accidental electrocution, lightning strike, or electroconvulsive shock therapy

•High electric energy absorbed by the lens causes coagulation of lens proteins

•Melanin of the pigmented iris creates high resistance to electric currents, resulting in heat build-up, which further enhances cataract formation

•Occur 2–6 months after injury

•Amount of tissue destruction depends on voltage, amperage, resistance, pathway, and duration of current flow

•Lightning has anywhere from 20 million to 1 billion volts of electric energy and can occur by direct strike, side flash, spray, or ground strike

Clinical Findings

•Acute:

• periorbital swelling or chemosis • ptosis • subconjunctival hemorrhage

•thermal keratopathy • hyphema • uveitis • transient or permanent pupillary abnormalities (dilated or non-reactive pupils are unreliable indicator of severe brainstem hypoxia in cases of lightning) • vitreous hemorrhage • commotio retina • retinal detachment • central retinal vein occlusion • macular hole

•chorioretinal rupture • thermal papillitis

•Less acute: cataracts

•accommodation abnormality • lightning (anterior and posterior subcapsular cataracts with distinctive fern-like or starburst appearance) • industrial electric injury (anterior subcapsular cataract only) • dislocated lens

posterior segment

•lightning maculopathy (pigmentary changes) • retinal detachment • macular hole

Ancillary Testing

• B-scan ultrasonography if fundus not visualized

Differential Diagnosis

• Anterior and posterior subcapsular cataracts of another etiology

Treatment

•In an acute lightning strike, high-dose corticosteroids may be helpful in the presence of significant vision loss due to optic neuropathy

•Lensectomy

Prognosis

• Good if isolated cataract

Fig. 4.10 Iridescent anterior and posterior lenticular changes forming a stellate pattern after a severe electric shock injury. The back of the patient’s head fell on to a 6900-V wire.

Fig. 4.11 A closer view of the other eye of the patient in Fig. 4.10, also with an electric shock cataract.

Fig. 4.12 A close-up of the eye shown in Fig. 4.11.

Cataract Shock Electric