For low vision specialists and those who consult them
Lutein for RP – hope or hype?
April 13, 2010Posted by on
There is an important article in the new Archives of Ophthalmology discussing the use of lutein supplements as a means to slow the progression of retinitis pigmentosa (RP). In it the authors find that mid-peripheral visual field loss is less likely to occur in people with RP taking Vitamin A + 12mg lutein than in people with equal levels of RP taking Vitamin A + a placebo.
Lutein is a naturally occuring carotenoid which is present in vegetables such as kale, spinach and broccoli. Along with zeaxanthin, it is found in the healthy retina and is a macular pigment. The 12mg dose is relatively small: about the same as half a potion of spinach.
In the same edition of the journal there is a very interesting editorial by Bob Massof and Gerald Fishman discussing the study. A major limitation which Massof and Fishman discuss is that there was no significant change on the primary outcome measure of the trial (visual field loss on a 30º visual field test). The difference which is reported in the paper (changes on a 60º field test) was a secondary outcome measure. In other words, the study was designed to measure change on a 30º field test, which did not occur. Massof and Fishman state that the study has not “convincingly proved that the treatments put on trial are effective in slowing the rate of progression of RP and, therefore, do not warrant mandating a change in how patients with RP are treated”.
I think that the Massof & Fishman argument is strong and eloquent, but I disagree with their final conclusion. I would agree wholeheartedly with them if lutein supplements had significant side effects, or were extremely expensive, or if the study was performed by someone who stood to profit out of lutein supplementation. None of these are the case.
I agree that more research is needed into the role of lutein in retinitis pigmentosa – in particular, a dose/response trial would be very useful – but pragmatically I think there is little to lose by suggesting that people with RP ensure their diet is rich in lutein (or take lutein supplementation).