A 50-Year-Old Patient's Left Eye Gradually Changes Color

Ronald C. Gentile, MD; Jonathan S. Lo; Chirag M. Shah, MPH

Disclosures

December 29, 2015

Case Diagnosis

The history of trauma with findings of heterochromia, corneal scar, cataract, uveitis, high intraocular pressure, and flat ERG support a diagnosis of siderosis bulbi. The patient's occupation as a construction worker using high-powered tools without protective eyewear is considered a risk factor.

Delayed diagnosis of a small metallic intraocular foreign body (IOFB) is not uncommon if the initial symptoms are mild and remitting. A UBM performed before CT identified the anteriorly located IOFB at the pars plicata in the left eye. The presence of a retained IOFB with flat ERG and other ocular signs of iron deposition confirm the diagnosis of siderosis bulbi.

FHU, also known as "Fuchs heterochromic iridocyclitis," is a chronic form of unilateral anterior uveitis that involves the iris and ciliary body. Although not clearly established, a viral etiology has been suspected. Chronic low-grade inflammation from FHU can cause heterochromia, cataract, and glaucoma. The affected eye rarely becomes darker (reverse heterochromia); although, owing to progressive iris atrophy, the iris typically becomes lighter in color compared with the unaffected eye. FHU is considered a diagnosis of exclusion, and other forms of infectious and noninfectious uveitis, including an occult IOFB, need to be ruled out.[1]

Retinitis pigmentosa is an inheritable, degenerative eye disease that causes vision loss and can present with a pigmentary retinopathy, cataract, and abnormal ERG. Even though the pigmentary retinopathy and ERG findings can be similar to those in eyes with siderosis bulbi, retinitis pigmentosa is typically a bilateral disease and usually presents with nyctalopia (night blindness), which was not observed in this patient. The absence of nyctalopia and family history with evidence of a secondary cause for the pigmentary retinopathy excludes this diagnosis.[2]

Horner syndrome is a disorder caused by a lack or blockage of the sympathetic nerves to the eye. The causes vary in terms of age of occurrence and level at which the sympathetic nerves are involved. Depending on the etiology, findings can include heterochromia, anisocoria, ptosis, anhidrosis, and enophthalmos.[3]Even though this patient had a lighter iris and smaller pupil on the right side, this was considered a normal finding, given that his other eye had siderosis bulbi with mydriasis and a darker iris.

Clinical Course

The patient underwent combined cataract extraction with 25/20+ gauge transconjunctival pars plana vitrectomy. A wire-shaped metallic foreign body 9 mm long and about 1 mm in diameter was removed. The IOFB was located superotemporally at the pars plana and was consistent with an 18-gauge nail used by the patient in his nail gun. The nail was made of galvanized steel, an iron/carbon alloy.

During surgery, the superior nasal sclerotomy was enlarged with an MVR blade to 1.5 mm in size. To visualize the IOFB, scleral depression was performed behind it. The IOFB was grasped using intraocular forceps at one end and was removed from the eye via the enlarged sclerotomy. Postoperatively, the vision in the left eye improved to 20/400, limited by the retinal iron toxicity and associated optic nerve atrophy.

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