A Sight for Sore Eyes

Extreme preemies experience greater vision problems despite medical advances

(RxWiki News) Improvements in medical technology and knowledge have meant tremendous progress in taking care of babies born extremely early and/or small. But many of these children still may face future challenges.

A recent study found that vision problems were more common among children born extremely early and/or extremely small.

Extreme preemies are born before 28 weeks and generally weigh two pounds or less.

The survival rates for these children increased in recent years. However, they were still at higher risk for problems with overall sight, depth perception and color blindness.

"Attend all prenatal appointments."

This study, led by Carly S. Molloy, PhD, of Murdoch Children's Research Institute in Melbourne, Australia, looked at the long-term effects on children's vision if they were born extremely preterm or with an extremely low birth weight.

An extremely low birth weight refers to babies born weighing less than 2.2 pounds. A normal birth weight is anything 5.5 pounds or greater.

An extremely preterm birth means being born before 28 weeks of pregnancy. A full term, normal pregnancy lasts 38 to 40 weeks.

The researchers followed 228 babies who were born extremely preterm and/or with an extremely low birth weight between 1991 and 1992 in Victoria, Australia.

The researchers compared the outcomes among these children to 166 randomly selected participants who were born with a normal birth weight.

The researchers specifically compared the vision of participants in both groups when they were between 14 and 20 years old.

The aspects of vision they looked at included color perception, depth perception and overall visual perception.

The researchers found that the children born extremely preterm and/or with an extremely low birth weight had significantly worse vision in both of their eyes.

The extremely preterm/low birth weight children were about three times more likely than the normal birth weight children to have problems with depth perception.

They were also about 2.8 times more likely to have problems with the way their eyes moved together, compared to the children born with a normal birth weight. This problem is related to the eyes' "convergence."

Difficulty with convergence means they had difficulty bringing their eyes together to see objects closer to them. Extreme convergence means being cross-eyed, but this was not observed in these children.

The researchers also found that children born extremely early or with extremely low birth weight were about three times more likely to have overall visual perception problems, even after correction with glasses or contacts.

"Preterm birth may have major consequences to the development of the visual pathway," the researchers wrote.

They noted that past research has shown that 50 to 65 percent of children born as preemies have at least one visual difficulty.

In this study, about 32 percent of the extremely preterm children wore corrective eyewear, such as glasses or contacts.

In addition, 43 percent had impaired vision in terms of how precisely they could see objects, how good their depth perception was, how well they could see objects close up or how well they saw color.

About 17 percent of the extremely preterm children in this study had two or more of these vision problems.

"It may be important to focus future research toward identifying those extremely low birth weight/extremely preterm infants most at risk, as well as developing clinical screening instruments and appropriate intervention programs to foster achievement within this domain," the researchers wrote.

This study was published August 5 in the journal Pediatrics.

The research was funded by the National Health and Medical Research Council and the Victorian Government's Operational Infrastructure Support Program. The authors declared no conflicts of interest.

Review Date: 
August 4, 2013