Toxic Retinopathy

 Toxic Retinopathy

Definition

Retinal changes resulting from use of medications.

Epidemiology: 

Toxic retinopathy is rare.

Pathogenesis: 

Toxic retinopathy can remain asymptomatic for a long time.

Loss of visual acuity occurs if the macula is affected.

Chloroquine in doses exceeding 250 g causes retinal damage. Macularedema can occur initially. Later, punctate pigment epithelial changes develop, which may progress to bull’s eye maculopathy with concentric rings of hypopigmentation and hyperpigmentation in the macular region (Fig. 12.32). These findings are usually bilateral and symmetrical. Other toxic retinal changes are listed in the appendix.


Diagnostic considerations: 

The diagnosis is made by binocular ophthalmos-copy with the pupil dilated and confirmed by electrophysiologic studies that include an electroretinogram, electro-oculogram, and visual evoked poten-tials (see Fig. 12.2a).


Differential diagnosis: 

Retinal pigment epithelium or retinal bleeding canresult from many other retinal disorders, and may also be associated with the underlying disease for which the medication was prescribed.

Treatment: 

The medication should be discontinued if possible.

Prophylaxis: 

Regular ophthalmologic follow-up examinations are indicatedbefore and during treatment that involves medications with known ocular side effects.

Clinical course and prognosis: 

The clinical course depends on the specificmedication and dose. Findings may improve after the medication is discon-tinued. However, with chloroquine in particular, findings may continue to worsen even years later.

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