Breast milk and eyes

Breast milk is a fluid of life, a precious food like few, and recent research has shown that it can also have therapeutic effects on eye injuries. The research, published in Current Eye Research, "Human Breast Milk Enhances Cellular Proliferation in Cornea Wound Healing"consolidates the hypothesis that the human breast milk may represent a potential therapeutic treatment, as it contains bioactive molecules that are important in the regeneration of epithelial cells.

Since the dawn of time, milk has been recognised as having thaumaturgical powers: the 'nectar of the gods', as the ancient Egyptians, Greeks and Romans called it, and in 18th century England it was even considered a life-saving drink.

Today, Dr Sarah N. Pimple and her colleagues from the Department of Ophthalmology at the University of Colorado's School of Medicine started from the anecdotes of new mothers who breastfed and told of using their milk to treat clogged tear ducts, rashes and corneal burns in infants. It must be kept in mind that the abrasions of the corneal epitheliumcaused by trauma or surgical wounds, are lesions that heal as new epithelial cells grow from the limbus in a centripetal direction and restore the epithelium.

The researchers then carried out preclinical research on laboratory mice in which corneal erosion was induced. One group of mice had human breast milk applied to the lesion, while in the control groups an ophthalmic ointment containing neomycin, dexamethasone, polymyxin B or saline solution was applied. The mice were treated four times a day for two days. The surprising result was that the corneas treated with human breast milk showed signs of re-epithelialisation already in the first 8 hours after epithelial débridement and application of breast milk, well before corneas treated with anti-inflammatories, antibiotics or saline solution.

As early as 2016, experimental evidence had emerged of milk's potential to promote the healing of corneal lesions, but the mechanisms and, in particular, what the cellular signal that activated the repair process. The study by the Colorado University team identified a particular marker of cell proliferation called Ki67a protein that is produced in cells that are actively dividing. Ki67 levels were higher in eyes treated with human breast milk.

It must be emphasised that in the case of corneal lesions, rapid healing is of paramount importance, as it prevents possible infections that could lead to much more serious eye problems, and it appears that breast milk can accelerate this process.

Breast milk contains on average 1.1% of protein, 4.2% of fat, 7% of carbohydrates, as well as vitamins E and C, as well as enzymes such as superoxide dismutase, catalase and glutathione peroxidase, which has relevant antioxidant properties.

It is not yet clear which substance contained in breast milk is able to activate the reparative corneal processes, but Professor Emily McCourt, of the research team, says that breast milk appears to have similar properties to eye medication obtained by centrifuging a patient's blood to separate the serum, which is then sterilised, bottled and used as eye drops in patients with severe dry eye or inflammatory eye disease.

Can we think about breast milk bottled and used as eye drops tomorrow? It is still early days, but there are good premises, also because breastfeeding also brings important benefits in terms of proper eye development.

It was, for example, observed that the serum lutein level of breastfed infants is higher than that of formula-fed babies. This parameter implies that infants are better protected against oxidative stress-induced diseases, particularly retinal diseases.

Similarly, breast milk provides a good supply of vitamin A, a vitamin crucial in the functioning of photoreceptors and in the physiology of vision in general. In particular, in children born preterm, before 37 weeks' gestation, with a still immature retinal structure and incomplete development of the retinal vasculature, the vitamin A intake provided by breast milk reduces the risk of onset and severity of ROP (Retinopathy of the Premature)by VEGF-A (Vascular Endothelial Growth Factor A). Compared to formula-fed infants, breastfed preterm infants also have higher levels of insulin-like growth factor-1 (IGF-1), which help counteract the risk of ROP.

Finally, breast milk is rich in a molecule, the phosphatidylcholinewhich is essential for phospholipid synthesis, DNA methylation and the neurodevelopmental process of the child involving the brain, retina and the entire neurovisual apparatus.

In the field of paediatric ophthalmology, we also point out:

• The 'digital health' of children and young people - Oculista Italiano
• WHO guidelines: to reduce children's exposure to digital screens
• Retinal trauma in children: watch out for the ball - Oculista Italiano

• Pimple SN, Pedler MG, Shieh B, et al. Human Breast Milk Enhances Cellular Proliferation in Cornea Wound Healing. Curr Eye Res. 2024 Nov;49(11):1138-1144. doi: 10.1080/02713683.2024.2374836. Epub 2024 Jul 9. PMID: 38979814.
• Lee V, Rompolas P. Corneal regeneration: insights into epithelial stem cell heterogeneity and dynamics. Curr Opin Genet Dev. 2022;77:101981. doi:10.1016/j.gde.2022.101981.
• Handelman GJ, Dratz EA, Reay CC, van Kuijk JG. Carotenoids in the human macula and whole retina. Investigative Ophthalmology & Visual Science. 1988;29(6):850-855
• Okamoto T, Shirai M, Kokubo M, et al. Human milk reduces the risk of retinal detachment in extremely low-birthweight infants. Pediatrics International. 2007;49(6):894-897