IDIOPATHIC AMBLYOPIA

Asymmetric bilateral birth haemorrhages with intraretinal, subretinal, white-centred and peripapillary flame haemorrhages in a term otherwise healthy infant. Image courtesy of Courtesy of Darius M Moshfeghi MD.

Approximately one-third of cases of amblyopia are deemed idiopathic. Now, using data collected in the Newborn Eye Screen Test (NEST) study, researchers are investigating whether retinal haemorrhage at birth may be an etiologic factor explaining at least some of those cases.

Under way at Stanford University, California, USA, NEST is a prospective cohort study that is evaluating universal newborn screening with wide-angle digital photography. At the 2015 annual meeting of the Association for Research in Vision and Ophthalmology in Denver, USA, Natalia Callaway MD, MS presented findings on the prevalence, characteristics, and potential risk factors for retinal haemorrhage at birth from data collected during the first year of NEST.

The analyses showed that retinal haemorrhages were common overall, being identified in >10 per cent of screened infants (n=202 at 12 months). The lesions were almost always present in multiple areas of the retina, and most often involved the macula and optic nerve while generally sparing the fovea.

Multivariable statistical analyses found that the odds of having a retinal haemorrhage were significantly higher among infants delivered vaginally compared to their counterparts born by Caesarean section. Self-identified Hispanic/Latino ethnicity appeared protective, reported Dr Callaway.

“Previous papers report that the majority of retinal haemorrhages present at birth resolve within four weeks. Haemorrhages that persist may be an amblyogenic factor by encroaching on the visual axis during the critical period of vision development,” she said.

LONGITUDINAL FOLLOW-UP

“Our investigation is the first prospective study of retinal haemorrhages at birth conducted in the United States that includes a diverse population and evaluates not only the prevalence of retinal haemorrhage, but also its characteristics. We will now be categorising haemorrhage severity in our cohort and we look forward to presenting the data on vision outcomes from longitudinal follow-up,” she added.

In NEST, screening is offered to all infants who do not receive retinopathy of prematurity screening. The images are taken by a trained neonatal intensive care unit nurse and interpreted by a paediatric vitreoretinal specialist.

Approximately one in four parents approached about the NEST study gave consent for participation. There were no significant differences between the enrolled infants and those whose families declined with respect to gender, birth weight, delivery method, or ethnicity.

Dr Callaway suggested that vaginal delivery might increase the risk of retinal haemorrhage by causing a rapid increase in intracranial pressure that affects retinal artery and retinal venous flow. A future analysis will investigate duration of the active phase of delivery as a risk factor.

Natalia Callaway:
nfijalk1@gmail.com

Darius M Moshfeghi MD,Director of Ophthalmic Telemedicine,
Byers Eye Institute, Stanford University School of Medicine: dariusm@stanford.edu