HBO Nuggets of the Week

A forum to discuss interesting aspects of hyperbaric medicine.

Monday, May 13, 2013

HBO Nugget 5

Patients undergoing hyperbaric oxygen treatment (HBOT) may complain of visual changes. Indeed, HBOT can affect one’s vision, but fortunately changes are usually self-limited.

When patients undergo HBOT at the typical prescribed parameters (2.0-2.4 atmosphere absolute for 90 minutes) they may develop myopia, or the inability to clearly see or focus on objects at a distance. The incidence may be as high as 20%-40%. The etiology is still not defined but appears to be related to temporary changes in the lens. There are some reports that there is a ¼ diopter change per week. The change usually regresses over about 6-8 weeks however there are reports of permanent change.

Cataract formation has been noted in some patients undergoing prolonged HBOT1; however, the incidence among patients receiving therapy within the usual prescribed parameters is extremely rare. Pre-existing cataracts in older adults can be accelerated to maturation for longer treatments and this change may not be reversible. Some hyperbaric centers will include pretreatment ophthalmologic consultation prior to the commencement of HBOT. For completeness, it should be mentioned that hyperoxia can cause retrolental fibroplasia in premature infants. Other studies have reported contraction of visual fields.

Anecdotally, some patients may enjoy a brief period of time when they do not need their reading glasses. But make sure they don’t throw them away.

Reference

1. Palmquist BM, Phillipson B, Barr PO. Nuclear cataract and myopia during hyperbaric oxygen therapy. Br J Opththalmol 1984;68:113-7.