Potassium iodate toxic retinopathy: a report of five cases.
BACKGROUND
Potassium iodate (KIO3) is an iodized salt used for iodine supplementation in areas endemic for goiter. KIO3 overdose in humans is rare. The authors report unusual cases of retinal toxicity from KIO3 overdose that caused acute vision loss.


METHODS
The clinical manifestations, toxic dosage of iodate, and ocular changes in five patients who had taken a KIO3 overdose were analyzed. Electroretinography, visual evoked potential (VEP), and fundus fluorescein angiography (FA) were performed to study retinal function and changes.


RESULTS
Two men and three women (age 22-65 years) ingested KIO3 solution at a concentration between 187 and 470 mg/kg body weight. Visual acuity ranged from light perception with projection to counting fingers and decreased from 2 to 12 hours after ingestion. Fundus FA showed bilateral extensive areas of retinal pigment epithelial (RPE) window defects, and electroretinography and VEP showed marked impairment of retinal function. Visual acuity improved from counting fingers to 20/80 in 3 months.


CONCLUSIONS
Potassium iodate can produce retinal toxicity that damages RPE and photoreceptor cells. The recovery of retinal function depends on the amount of chemical absorption, the regeneration of RPE, and the recovery function of photoreceptor cells.
Singalavanija
A
A
Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Ruangvaravate
N
N
Dulayajinda
D
D
D000284:Administration, Oral; D000368:Aged; D004596:Electroretinography / Q000187:drug effects; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006801:Humans; D007452:Iodates / Q000008:administration & dosage / Q000506:poisoning*; D008297:Male; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D017680:Potassium Compounds / Q000008:administration & dosage / Q000506:poisoning*; D011379:Prognosis; D012164:Retinal Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D014792:Visual Acuity / Q000187:drug effects
D007452:Iodates; D017680:Potassium Compounds; C039693:potassium iodate