Iodine may alleviate retinitis pigmentosa swelling

Boston-Researchers from Massachusetts Eye and Ear, Harvard Medical School, and Boston University School of Medicine have found that the extent of retinal swelling due to cystoid macular edema (CME) was inversely related to dietary iodine intake in patients with retinitis pigmentosa (RP).

The finding raises the possibility that an iodine supplement could help limit or reduce central foveal swelling in RP patients with CME, according to the researchers. Their results can be found online in the July issue of JAMA Ophthalmology.

Previous research performed showed an inverse association between the presence of CME and reported iodine supplementation in patients with RP. This finding, along with physiology research by others, pointed to iodine as being worth investigating further.

In this new experiment, the researchers performed a cross-sectional observational study of 212 non-smoking patients 18 to 69 years of age who were referred to Massachusetts Eye and Ear for RP with visual acuity of no worse than 20/200 in at least one eye. They then used optical coherence tomography to measure central foveal swelling due to CME in the patients. Total dietary intake of iodine was estimated from multiple spot urine samples collected at the patients’ home.

The investigators found that the magnitude of central foveal swelling due to CME was inversely related to urinary iodine concentration when emphasizing data with more reproducible urinary idodine concentrations (p < .001). Patients with the lowest urinary iodine levels tended to have retinas with the most swelling, according to the researchers.

“Additional study is required to determine whether an iodine supplement can limit or reduce the extent of CME in patients with RP,” said Michael A. Sandberg, PhD, lead author of the study and senior scientist in the Berman-Gund Laboratory for the Study of Retinal Degenerations at Massachusetts Eye and Ear, and associate professor of ophthalmology, Harvard Medical School.

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