Bringing the issue into focus

Jane Barry makes the link between nutrition and infant eye health.

As an issue, infant eye health has not been high on the agenda for many child and family health nurses. It competes for attention and surveillance among other, often complex physical and social assessments.

But advances in research surrounding this topic indicate it may be time for a change in our current practice. Not only for benefits during childhood, but throughout adult life as well.

It has been long understood that the critical period for vision development in humans occurs between the ages of birth and eight years. At the core of this development is growth of the eye itself, which takes up to three years to reach its full adult size.

Vision is not well advanced at birth, however, it does mature quickly. Assessment of visual disruption in the early years is essential in order to both treat and prevent further impairment so that optimal sight is supported.

Factors influencing vision

Some of the more common factors which influence vision are age, prematurity, economic status, sun exposure, nutrition and exposure to oxidative stressors.

Prematurity in particular is an area of concern as the infant eye undergoes rapid growth especially in the last 10 weeks of gestation. Premature birth retards retinal vascular development, and Retinopathy of Prematurity (ROP) continues to be a significant cause of childhood blindness.

Congenital cataract, likewise, leads to impairment of visual development as a clear visual axis is critical.

Observational assessments

During health checks, it is important for nurses to observe any infant or child with an unusual presentation which could suggest visual problems. These include an unusual head posture or appearance of one or both eyes, problems with eye contact, an inability to fix and follow from around six weeks of age, an unusual level of alertness or awareness and disinterest in toys.

One of the standard assessments used by nurses at universal health checks is to examine a child’s corneal light reflex (CLR). An unequal reflection, either unilateral or bilateral may indicate strabismus (squint). Without effective treatment, strabismus can lead to amblyopia (commonly referred to as lazy eye) and a loss of binocular depth perception. Early specialist assessment and treatment for strabismus optimises effective outcomes.

Other obvious problems may be the presence of sticky eyes, conjunctivitis, puffy or swollen eyes, particularly in the newborn period. While these do not lead to permanent visual compromise, they are worth noting and referral for medical assessment is warranted if they do not resolve.

The link between nutrition and eye health

Children are not born with clear vision, however, by twelve months their visual acuity almost matches an adult. Central to this development is the influence of specific dietary nutrients, in particular vitamin A, DHA, antioxidants, taurine and lutein or zeaxanthin.

All of these nutrients play both specific and generally protective roles. In particular, the carotenoids lutein and zeaxanthin target the retinal macula, a nutritionally responsive area and one prone to early damage from high energy blue light.

These compounds work by filtering and absorbing hazardous blue light as well as providing protective antioxidant qualities. Infants have retinas under significantly higher levels of oxidative stress in comparison to adults, due to higher metabolic activity in this region.

The retina is the area of the eye where light is focused and our most acute vision occurs.

Cumulative damage to the retina, as seen in age-related macular degeneration (AMD), starts in infancy, when the crystalline lens of the eye is so transparent it provides little protection against high energy light.

AMD is the most common form of blindness in Australia and affects the central vision. Early oxidative damage to the retina can be most severe in the first 10 years of life, giving cause for those involved in infant health and child health to prioritize eye health awareness messages.

Human breast milk is the optimal nutrition for infants. It provides exactly the right balance of essential nutrients,not only for generalised growth but for health and development of the visual system.

In the months before solid foods are introduced breast milk and formula are the only sources of lutein and zeaxanthin. Breast milk concentrates of lutein and zeaxanthin vary according to the mother’s own intake.

Primary, rich sources of these carotenoid compounds are found in green leafy vegetables such as kale, spinach, peas, lettuce, broccoli, pumpkin and corn. It is important for lactating mothers to eat a diet which includes these as well as other fruits and vegetables, not only for her own health but for her baby as well.

Lutein levels in both formula and breastfed babies are similar at birth, but by one month the former show a reduction in serum lutein levels and the latter an increase. Supplementing infant formula with lutein or Zeaxanthin to match breastmilk levels is currently thought to be beneficial.

The recent Food Standards Australia New Zealand (FSANZ) approval of lutein as a nutritive ingredient has opened the door for innovation in this area.

Jane Barry is a registered and child health nurse. She received honorarium to attend the Paediatric Eye Health Summit and conduct her research from Wyeth Nutrition. For a referenced copy of the article email [email protected]

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