In the news: Omega-3s Protect Corneal Nerve in Type 1s, Obesity Ups Risk of Some Eye Diseases, & NEI Follow-up Affirms AREDS2 Results

Omega-3s Neuroprotective in Type 1 Diabetes

Diabetic sensorimotor polyneuropathy (DSP), also called diabetic peripheral neuropathy, is the most common diabetic complication – about 50% of diabetics are affected. Early-stage DSP is associated with loss of small sensory corneal nerve fibers, and monitoring changes in the corneal nerve provides a non-invasive, sensitive, and reliable marker for DSP progression.

Since intensive blood glucose control is the only established method for slowing DSP in type 1 diabetes, more therapies are needed to reduce progressive peripheral nerve damage. Based on results from animal studies and an open label trial in type 1 diabetics, the omega-3 fatty acids may be one promising intervention. This prompted University of Melbourne researchers to conduct a randomized, controlled pilot trial to observe the effects of supplemental omega-3 fatty acids in type 1 diabetics.

They report that 6 months of supplemental omega-3 promotes corneal nerve regeneration.

In the study(1), type 1 diabetics received either 1800 mg of fish oil or a similar placebo of olive oil. The 1° end-point was change in corneal nerve fiber length (CNFL). After 180 days, the increase in CNFL for the omega-3 group compared to placebo was 2.70 mm/mm2 (p<0.001). No between-group differences in most small or large nerve fiber function was observed.

The findings are “consistent with a corneal neuro-regenerative effect”, according to the authors who call for trials to assess whether these fatty acids confer similar benefits in peripheral nerve structure / function.

Obesity as Risk Factor in Age-Related Eye Disease

The relationship between obesity and age-related ocular diseases including cataract, glaucoma, AMD, and diabetic retinopathy (DR) have remained somewhat elusive. Now a new systematic review(2)reports that, overall, evidence supports associations between obesity and age-related eye diseases.

Researchers from London, Singapore and Germany teamed to conduct a systematic review of longitudinal population-based studies that described associations between measures of obesity including body mass index (BMI), waist-circumference (WC), and waist-to-hip ratio (WHR), and age-related eye diseases. WC and WHR are measures of abdominal obesity – a hallmark of insulin resistance. The search yielded 14, 10, 16 and 8 papers meeting eligibility criteria for cataract, glaucoma, AMD, and diabetic retinopathy (DR), respectively.

BMI-defined obesity was positively associated with incident cataract, AMD and DR in Western populations, but in Asian populations associations with incident AMD were not significant and associations for DR were inverse. WC-defined obesity was linked to incident glaucoma in non-Western populations, while WHR-defined obesity was linked to incidence or progression of AMD in Western populations. Studies are needed to answer the question: Does weight loss reduce eye disease risk in the obese?

10-Yr Follow-Up Study Affirms AREDS2 Findings

When the 5-year AREDS2 trial ended, a follow-up study(3) was initiated with telephone calls every 6 months for 5 years to collect further information.

In brief, the AREDS2 trial was designed to test the effect of adding lutein/zeaxanthin (L/Z) and fish oil to the original AREDS formula. The results showed that fish oil offered no benefit beyond the AREDS supplements while L/Z reduced progress to vision-threatening AMD vs. beta carotene, which also doubled the chance of lung cancer.

The current follow-up study results prevented this month at ARVO showed a more favorable response for L/Z than beta carotene and that L/Z was safer, as beta carotene again doubled lung cancer risk. For more details see abstract: https://arvo2021.arvo.org/meetings/virtual/kbJm2RP9iWdhetrp9

References

1. Britten-Jones AC, et al. Investigating the neuroPRotective effect of Oral Omega-3 Fatty acid Supplementation in type 1 diabetes (nPROOFS1): a randomized, placebo-controlled trial. Diabetes. db210136, May 2021.
2. Ling CNY, et al. Obesity and risk of age-related eye diseases: a systematic review of prospective population-based studies. Int J Obesity. Published online ahead of print May 7, 2021.
3. Chew E, et al. The results of the 10-year follow-on study of the age-related eye disease study (AREDS2). Presented at the 2021 ARVO Annual Meeting, May 7th.