Prospective study of New Zealand infants with birth weight less than 1500 g and screened for retinopathy of prematurity: visual outcome at age 7-8 years.

AIM

To determine the visual outcome at 7-8 years in very low birth weight (VLBW: birth weight < 1500 g) infants screened for retinopathy of prematurity (ROP).

METHODS

In 1986 all 413 VLBW infants admitted to neonatal units in New Zealand were enrolled in a prospective study of acute ROP. Surviving infants were traced and assessed at a home visit. Visual assessment comprised examination for abnormal and range of eye movements, visual fields, distance and near visual acuity, stereopsis, and photorefraction.

RESULTS

Of 338 infants surviving to discharge, 313 (93%) had been examined for acute ROP. ROP was present in 66 (21%: ROP+), absent in 247 (ROP-), with 25 not examined (NA). 298 children (96% survivors resident in New Zealand: 91% all survivors) were assessed. Any visual problem occurred in 79% ROP+ and 60% ROP-/NA (p < 0.01). Distance visual acuity less than 4/10 in the worse eye occurred in 29% ROP+ and 15% ROP-/NA (p < 0.05); and in the better eye in 19% ROP+ and 5% ROP-/NA (p < 0.001). Any myopia in the worse eye occurred in 36% ROP+ and 18% ROP-/NA (p < 0.01); and in the better eye in 25% ROP+ and 11% ROP-/NA (p < 0.01). Strabismus, including treated, occurred in 33% ROP+ and 19% ROP-/NA (p < 0.05). Overall, 11% had astigmatism and 18% hypermetropia with no difference between the groups.

CONCLUSION

In a population based study it was confirmed that VLBW is associated with an increased risk of visual problems at school age. A history of ROP is associated with an additional risk of poor outcome, including a near doubling of poor distance acuity, myopia, and strabismus.