Aetiology

ROP is a multifactorial condition. Aside from prematurity and low birth weight, the best known aetiological factor is that of hyperoxia but the condition may develop in the absence of supplementary oxygen and children exposed to high doses do not necessarily develop ROP.

Others risk factors include:

• repeated blood transfusion
• prolonged parenteral nutrition
• hypercarbia
• hypocarbia
• seen in congenital cyanotic heart disease - ie importantly not solely associated with hyperoxic states
• hypoxia - controversial; often a history of anoxia in the immediate postnatal period, but hard to confirm in studies

Features thought NOT to be factors include:

• heparin
• multiple birth, except where this results in prematurity
• sex - equal prevalence in boys and girls, given other risk factors
• race - although some reports state that Afro- Caribbeans are more at risk; this may be an social phenomenon
• history of maternal substance abuse
• vitamin E deficiency - controversial; vitamin E has been claimed to protect in the past but the effect has now been reported to be statistically insignificant