ROP Screening

This article discusses Retinopathy of prematurity, ROP screening.

When Should ROP Screening Start?

Preterm babies are not born with ROP as it only develops during the first few weeks after birth. The scheduling of ROP screening examinations should ensure that eyes likely to need treatment are identified in a timely manner and minimise the number of examinations for babies at low risk of ROP.

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In high resource settings, where the quality of neonatal care is high, ROP takes longer to develop in very immature infants.

In babies less than 27 weeks gestational age the screening is planned when they are at a postmenstrual age of 30 to 31 weeks.

For babies born between 27 to 32 weeks gestational age the first screening should ideally should take place by four to five weeks after birth.

For babies over 33 weeks gestational age screening is planned for the fourth week after birth.

In low resource settings, where the quality of neonatal care is often less good, babies may have been exposed to hyperoxia (excessive oxygen supply) for several days and in situations where the gestational age is often unreliable or unknown, it is useful to have guidelines for the timing of the first screening which are easy to remember and implement. For example, in Indian guidelines, the first screening must take place by 30 days of life or at four weeks after birth.

If the baby is very premature or has been very sick or received a lot of oxygen, earlier screening should be considered, such as between 21 and 25 days of life, but more research is needed.

After Screening: Management Decision

At each screening, including the first, one of three management decisions is made:

• Urgent treatment is needed, or
• Follow up screening is needed, or
• It is safe to stop screening.

If treatment is needed, this must be delivered within 48 to 72 hours, or even earlier if aggressive posterior ROP is detected.

Follow-up screening is needed if the retinal blood vessels are not mature, whether ROP is present or not. The timing of follow up screening depending on the findings is shown in the table below. If further screening is needed, the date of the next screening examination must be documented and explained to parents. If the baby is likely to be discharged before the next screening is due, it is important to tell parents where the screening will take place, and the date and time. This should also be given to them in writing so they have a record.

Stopping screening: All eligible babies must be screened before discharge or transfer to another neonatal unit. Making sure this happens improves the parents’ awareness of ROP and, if the retinal blood vessels are mature at the first examination, they can be told that they do not need to bring their baby back for further screening. Examination before discharge has been shown to increase compliance with screening after discharge, if needed.

Management decisions are shown in the practical Job Aid below, which you can download and use in your setting as a guide

Documenting and Communicating Findings and Management Decisions

It is very important that accurate records are kept at every screening for all babies who have been screened for ROP. The following should be entered into the infant’s medical records:

• Date of screening
• Findings for both eyes
• Management decision, including when the next screening should take place, and the signature of the screener
• If parents refuse screening this should also be documented
• One of the parents and the screener should both sign the statement.

This helps to ensure that babies are screened at the right time, that follow-up screening is done when needed and for medico-legal reasons.

Additional Advances Taking Place: Does Weight Gain Predict Rop?

Currently, gestational age and birth weight are the most frequently used criteria for screening and some countries add ‘sickness’ or ‘exposure to risk factors’ criteria. However, as we have seen above, there are limitations and challenges with all of these criteria. This has led researchers to explore other factors which may help to predict which babies are at the greatest risk and, conversely, those at low risk.

Several studies have investigated change in insulin-like growth factor 1 during the first few weeks of life, and although the findings were encouraging in predicting babies most at risk, the assays are expensive and need to be repeated. This has led researchers to investigate weight gain during the first few weeks of life as a surrogate for insulin-like growth factor 1, and several different groups have developed statistical models. These studies show that slow, early postnatal weight gain does predict sight-threatening ROP, but the sensitivity can be less than 100% (Lin and Bibenbaum 2019). This means that weight gain alone cannot be used to reliably identify all babies who subsequently develop sight-threatening ROP. Another limitation is that all the statistical models have been developed in high income settings using data from very preterm babies who have received excellent neonatal care, and studies show that they do not predict sight-threatening ROP in settings where babies are more exposed to risk factors.

In an ideal world, only babies at very high risk of developing sight-threatening ROP would be screened. This would reduce stress to the babies screened unnecessarily, and reduce the cost of screening for service providers and parents. However, we are still a long way from this ideal.