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Lutein & Vitamin A May Slow Mid-Peripheral Vision Loss in Retinitis Pigmentosa

Lutein and Vitamin A in Retinitis Pigmentosa

Retinitis pigmentosa (RP) causes progressive vision loss to about 1 in 4000 people worldwide. Patients typically report deficient night vision in adolescence, and loss of mid-peripheral and then far peripheral field in adulthood with development of tunnel vision. Central vision is usually lost after age 60.

The previous EduFacts (Vol. 11, No. 1) summarized an investigation that found macular pigment optical density (MPOD) to be independently related to serum lutein in patients with retinitis pigmentosa (1). Provocative results from a new clinical trial suggest daily supplementation with lutein and vitamin A may help preserve mid-peripheral vision in RP (2).

Study Design

The objective of this randomized, controlled, double-masked trial was to determine whether lutein supplementation slows visual function decline in patients with RP also receiving vitamin A at a level previously reported by the same investigators to slow the rate of RP progression.

225 non-smoking patients, aged 18 to 60 years, were evaluated over a 4-year interval. Patients received 12 mg of lutein or placebo daily in addition to 15,000 IU/day of vitamin A palmitate. Randomization took into account genetic type and baseline serum lutein level.

The primary outcome was the total point score for the Humphrey Field Analyzer (HFA) 30-2 program. Secondary outcomes were the total point scores for the 60-4 program and for the 30-2 and 60-4 programs combined, 30-Hz electroretinogram (ERG) amplitude, and Early Treatment Diabetic Retinopathy Study acuity.

Results

There was no difference between groups in the rate of loss for the primary outcome measure, or in the secondary outcome measures between groups for rates of loss of the HFA 30-2 plus 60-4 total point score, ERG amplitude, or visual acuity. However, a significant effect of treatment on the rate of loss for the HFA 60-4 total point score (p=.05) was observed. Mean decline with the 60-4 program was slower among those with the highest serum lutein level or with the highest increase in MPOD at follow up (p=.01 and p=.006, respectively). Those with the highest increase in MPOD also had the slowest decline in HFA 30-2 and 60-4 combined field sensitivity (p=.005).

Comments

The researchers conclude that their data support the use of 12 mg / day of lutein to slow visual field loss among nonsmoking adults with RP taking vitamin A. They estimate that, based on the randomized comparison, the benefit in preserving mid-peripheral field sensitivity would be 3 additional years. Based on MPOD observational results, they estimate that the benefit would be 10 additional years. In the latter case, a patient taking vitamin A who begins supplemental lutein at age 40 could expect to lose mid-peripheral field by age 61 compared to age 51 for those not taking lutein according to the authors. Patient follow-up would be needed to confirm these estimates.

In an accompanying editorial (3), Massof and Fishman point out that this study, as well as 2 previous trials conducted by the same researchers produced no clear-cut results. One trial tested vitamin A, while the other evaluated vitamin A with 1,200 of DHA daily. According to the editorial, while all 3 trials were well designed and executed, they raise 2 issues: 1) the risk of misinterpreting outcomes because of assumptions built into the data analysis, and 2) the question of how much weight should be placed on clinical recommendations that are based on secondary analyses.

Although some might argue that there is no other viable treatment for RP and the conclusions drawn by the investigators are reasonable, the editorial concludes that neither vitamin A with lutein nor with a diet high in omega-3 have been convincingly shown to slow the rate of progression of RP.

References

1. Sandberg MA, et al. The relationship of macular pigment optical density to serum lutein in retinitis pigmentosa.Invest Ophthalmol Vis 51:1086–91, 2010.
2. Berson EL, et al. Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol 128:403-11, 2010.
3. Massof RW and Fishman GA. How strong is the evidence that nutritional supplements slow the progression of retinitis pigmentosa? Arch Opthalmol 128:493-5, 2010.