What ROP is

The blood vessels that supply the retina finish growing in the last weeks of pregnancy. When a baby is born before that is done, the process is interrupted and can then restart abnormally, producing fragile vessels, and in severe cases scarring that pulls on the retina. That is retinopathy of prematurity, usually shortened to ROP.

The RCPCH sums up the shape of the problem: "Many extremely preterm babies will develop some degree of retinopathy of prematurity (ROP) with the majority of cases never progressing beyond mild disease, resolving spontaneously without treatment. However, a small proportion develop potentially severe ROP which can be detected through retinal screening."

The important half of that sentence is the first half. Being told your baby "has ROP" most often means mild changes that will go away. The reason the screening programme exists is the minority for whom it will not, and for whom timing is everything — the RCPCH notes ROP "is one of the few causes of childhood visual disability that is largely preventable".

Who gets screened in the UK

The UK screening guideline is produced by the RCPCH with the Royal College of Ophthalmologists and BAPM. It was published in 2022, revised in October 2024, and is due for review in 2027. The original 2008 version was developed with Bliss.

The criteria are gestational age and birthweight. Babies born at less than 31 weeks' gestational age, or with a birthweight lower than 1501g, are screened. The 2024 revision added a recommendation to consider screening babies born between 31+0 and 31+6 weeks. Before 2022 the gestational threshold was 32 weeks, so if you are comparing notes with someone whose baby was born a few years earlier, the rules they remember may not be the current ones.

Screening is timed rather than one-off. The first examination is scheduled by gestational age at birth and postmenstrual age, and screening continues at intervals until the retina is judged to have finished vascularising or the risk period has passed.

What the examination involves

An ophthalmologist or specially trained screener examines the retina, usually with drops to widen the pupils and a speculum to hold the eyelids, sometimes with a wide-field camera instead of or as well as direct examination. It takes a few minutes per baby.

It is uncomfortable, and the guideline takes that seriously: the 2022 update added detail on preparation for screening, including consent, comfort care and pain relief during the examination. Sucrose, a dummy, containment holding and having a parent present are all used. You can ask to be there. You can also ask for the comfort measures if they are not offered.

Screening days are hard to watch and babies are often unsettled for a while afterwards. That is normal and it passes.

Zones, stages and plus disease

Reports use three descriptors together. Zone says how far the vessels have grown out from the optic nerve, with zone 1 the most central and the most concerning. Stage, 1 to 5, describes how abnormal the boundary between vascularised and non-vascularised retina looks, with stages 1 and 2 mild and stage 4 or 5 involving retinal detachment. Plus disease means the vessels at the back of the eye are dilated and tortuous, and it is the single most important sign that disease is active and progressing.

None of these means anything on its own. A stage 2 in zone 3 without plus disease is usually watched. A lower stage in zone 1 with plus disease may be treated urgently. This is precisely why the guideline exists and why treatment decisions belong to the ophthalmology team rather than to a table.

Treatment

Treatment aims to stop the abnormal vessel growth before it damages the retina. Laser treatment to the peripheral retina has been the mainstay for decades. Injections of anti-VEGF drugs into the eye are also used, and the choice between them depends on the zone, the baby's condition and the unit. Treatment is done under sedation or anaesthesia, and babies are usually re-examined frequently afterwards. The RCOphth maintains the separate UK guideline covering treatment.

Questions worth asking

Screening generates a stream of results and very little explanation, largely because the examining ophthalmologist is often moving between babies. Four questions get you most of what you need:

What zone and stage was seen today, and is there plus disease?
Is this better, the same or worse than the last examination?
When is the next screen, and what would bring it forward?
If treatment becomes necessary, would it be done here or would we transfer?

The RCPCH also publishes an information leaflet for parents and carers alongside the clinical guideline, which is worth asking your unit for. The guideline emphasises the role of a ROP service coordinator and of communication with parents, so if screening appointments are being missed or you are not being told results, that is a gap in the pathway rather than something you should be chasing alone.

Vision afterwards

Most babies who had mild ROP that resolved have normal vision. Babies who needed treatment usually keep useful sight, but are more likely to need glasses, to develop a squint or a lazy eye, and to need long-term ophthalmology follow-up. The WHO notes that visual problems are among the lifelong difficulties faced by some survivors of very preterm birth, and NICE guideline NG72 lists severe ROP as an independent risk factor for motor function problems and, in babies born before 28 weeks, for learning disability — which is why eye disease is one of the things that triggers enhanced developmental follow-up rather than only eye follow-up.

Practically: keep every ophthalmology appointment, including the ones years later when your child seems fine. Refractive problems and squints are treatable when caught early and much harder to treat once vision has settled.

Retinopathy of Prematurity