In rare cases ROP has been found in some patients with a mutation in the NDP gene, which is normally associated with the more damaging Norrie disease.

When the excess oxygen environment is removed, the blood vessels rapidly begin forming again and grow into the vitreous humor of the eye from the retina.

Restricting supplemental oxygen use reduces the rate of ROP, but may raise the risk of other hypoxia-related systemic complications, including death.

[9] Patients with ROP, particularly those who have developed severe disease needing treatment are at greater risk for strabismus, glaucoma, cataracts and shortsightedness (myopia) later in life and should be examined yearly to help prevent or detect and treat these conditions.

In addition to retinal manifestations, children tend to have amblyopia, strabismus, cataracts, glaucoma, nystagmus and corneal problems.

In older patients, the appearance of the disease is less well described but includes the residua of the ICROP stages as well as secondary retinal responses.

The system used for describing the findings of active ROP is entitled The International Classification of Retinopathy of Prematurity (ICROP).

The circumferential extent of the disease is described in segments as if the top of the eye were 12 on the face of an analog clock, e.g. stage 1 from 4:00 to 7:00.

[15] Any premature baby with severe illness in perinatal period (respiratory distress syndrome, sepsis, blood transfusion, intraventricular haemorrhage, apnoeic episodes, etc.)

Following pupillary dilation using eye drops, the retina is examined using a special lighted instrument (an indirect ophthalmoscope).

The stage of ROP refers to the character of the leading edge of growing retinal blood vessels (at the vascular-avascular border).

In order to allow timely intervention, a system of monitoring is undertaken for infants at risk of developing ROP.

In the USA the consensus statement of experts is informed by data derived by clinical trials and published in Pediatrics 2006.

[25] There is increasing evidence that ROP and blindness due to ROP are now public health problems in the middle income countries of Latin America, Eastern Europe and the more advanced economies in South East Asia and the Middle east region.

There is also evidence that the population of premature infants at risk of severe ROP varies depending on the level of neonatal intensive care being provided.

[26] In countries with high development indices and very low neonatal mortality rates (e.g. North America, Western Europe), severe ROP is generally limited to extremely preterm infants i.e. those weighing less than 1 kg (2.2 lbs) at birth.

However, Kate Isabel Campbell (1889–1986), a specialist in children's diseases, was responsible in 1951 for proving the link between retrolental fibroplasia (a blindness in premature babies) and oxygen levels in humidicribs.

Babies born prematurely in such affluent areas were treated in incubators which had artificially high levels of oxygen.