Long-term ocular complications in children born preterm

The development of the eye is complex and closely linked with the development of the brain. The following three factors influence visual outcomes for infants and children born preterm:

• The degree of prematurity and how sick the baby was
• Whether retinopathy of prematurity developed and how severe it was
• Whether neurological lesions developed in utero, during delivery or after birth.

Refractive errors, where light entering the eye is not focused properly on the retina, are more common in children born preterm than at term. The risk is higher if ROP developed, and far higher if treatment was given.

In refractive errors there is a mismatch between the focusing ability of the structures at the front of the eye (the cornea and lens) and the length of the eye.

‘Emmetropisation’ is the process of refractive development whereby the ocular components grow in a coordinated fashion to create an eye without refractive error. This process, which is fine-tuned by vision, is jeopardised in the preterm baby for two reasons: first, the effect of being born preterm and second, as a consequence of ROP. Early exteriorisation due to preterm birth shortens the intrauterine period and removes the fetus from a protective environment ideally suited to promote growth and provides the optimal level of stimulation. Unsurprisingly, the visual system of the preterm baby can be affected by removal from this milieu as well as by exposure to a very different biological and physical environment. Fledelius demonstrated over 30 years ago that the eyes of children born prematurely but who did not have ROP did not grow normally. He showed that structures at the front of the eye, namely the cornea and lens, both of which play a vital role in focusing light onto the retina, were different: corneas of children born preterm are more curved, and the lens is thicker, both of which increase the focusing power of the eye, leading to short-sightedness (myopia). This myopia, which is not due to ROP, is of low degree and is referred to as ‘myopia of prematurity’.’

Excerpted from Fielder, A. et al. Impact of retinopathy of prematurity on ocular structures and visual functions. Archives of Disease in Childhood – Fetal and Neonatal Edition 2015;100:F179-F184.

As you watch this video consider the different teams and services which are needed to support follow-up care for preterm babies.