Retinopathy of Prematurity (ROP) is a disease of the eye affecting preterm born babies. It is characterised by changes in the developing blood vessels of the retina (the light-sensitive layer in the back of the eye that sends visual signals to the brain). All preterm babies born before around 31 weeks of pregnancy or having a birth weight of less than 1,250g to 1,500g need to have eye examinations by a specialised eye doctor, called ophthalmologist, to check how the vessels in the eye develop.

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This ensures that the development of ROP is detected early and can be treated if needed. Since there is a lag period after birth until ROP develops, the first screening usually takes place after four to six weeks following birth. It continues until the ophthalmologist can note that the vessels have fully grown in the outer parts of the eye and any ROP has resolved. Increasingly, photographs of the retina are being taken either by NICU personnel or by staff from the ophthalmology department for the ophthalmologist to evaluate the status of the eye and to document how the vessels develop.

From the point of view of our monthly topic “Data collection and documentation” in February, we are especially interested in the question, how single hospitals can evaluate their patients with retinopathy of prematurity, as they usually have only very few cases within a year. To provide all stakeholders with reliable information and outcomes, systematic collections of reliable data of quality registries focused on ROP for clinical research are of utmost importance as they help that different hospitals can evaluate their cases together and can compare the patients within a country, but even between countries.

We thus would like to present you two national ROP registries, the Retina.net ROP registry from Germany and the SWEDROP registry from Sweden and talked to the medical experts in charge, Professor Andreas Stahl (Retina.net ROP registry), Head of Ophthalmology at the Greifswald University Medical Center, Germany, and Professor Ann Hellström, Professor in Pediatric Ophthalmology, Sahlgrenska Academy, from The Queen Silvia Children´s Hospital, Göteborg, Sweden, and Professor Gerd Holmström (register holder), Department of Ophthalmology at the University Hospital Uppsala, Sweden.

The German Retina.net ROP registry is a collaborative network of academic institutions in Germany. It was created as a joint effort to acquire sufficient data of treated infants in a multicentre approach to analyse typical clinical features of infants, epidemiology, and treatment patterns of severe ROP.
SWEDROP is a national quality registry to evaluate screening and treatment for ROP in Sweden and to investigate possible modifications of the present screening guidelines. Almost all infants in Sweden born before a gestational age (GA) of 31 weeks are screened for ROP until the retina is fully vascularised, approximately at 40 weeks postmenstrual age (PMA). SWEDROP is organised through a steering committee where representatives from the University Hospitals (n=7) collaborate and are responsible to capture data from their regions.

How long does the registry exist?
• Retina.net (Professor Stahl): Since 2011
• SWEDROP (Professor Holmström / Professor Hellström): Since 2007, but with reliable results from 2008.

On how many infants do you have information in your registry at the moment (February 2019)?
• Retina.net: 308 infants treated for ROP
• SWEDROP: Almost 10.000 preterm born infants, where approximately 500 have been treated for ROP.

How many medical centres do collect information in your registry?
• Retina.net: 14
• SWEDROP: Around 30

Do you collect data from all preterm infants in your country with regard to ROP?
• Retina.net: No. Data entry is voluntary and we rely on centres that are motivated to participate. We estimate that we cover around 10 – 15% of treated ROP cases in Germany.
• SWEDROP: Yes – the national coverage is around 97 – 98% of all infants born in Sweden with a GA of less than 31 weeks.

Do you collect information on infants who do not get ROP?
• Retina.net: No. In the German ROP registry only collects information from infants who are treated for ROP. This is done to keep the required time commitment at a minimum since only few data sets per center need to be entered annualy. We do, however, aim to collect as many follow-up data as possible from all treated infants.
• SWEDROP: Yes.

What information on ROP do you collect?
• Retina.net: We obtain information on stage and zone at time of treatment, presence of plus disease, the type of treatment, follow-up, and how ROP develops.
• SWEDROP: We collect data on stage, zone and type of ROP, plus disease, onset of the ROP disease, treatment details (type of treatment), start of the screening, number of examinations, time at onset of the different stages of ROP and at treatment.

Do you collect follow-up information? If yes, how long?
• Retina.net: Yes, the centres can document every follow-up examination up to a total of (theoretically) 99 follow-up examinations.
• SWEDROP: We only collect follow-up information of those who have been treated for ROP, and only at the age of 6.5 years. In addition, follow-up at 2.5 years is optional, but we do have standardised protocol.

What information apart from ROP do you collect?
• Retina.net: Baseline characteristics (e.g. birth weight, age at birth), neonatal data (e.g. oxygen treatment, number of blood transfusions, bronchopulmonary dysplasia (BPD), hydrocephalus, sepsis, infections, treatment of patent ductus arteriosus (PDA), systemic and ophthalmological complications etc.)
• SWEDROP: None within SWEDROP, but we can connect the data with information collected in the neonatal registry (SNQ) for neonatal morbidities (intraventricular hemorrhage (IVH), BPD, necrotizing enterocolitis (NEC) and sepsis) as well as information regarding WINROP outcome (optional). WINROP is an online monitoring system, following weight gain, for predicting the development of ROP in patients and was developed by the research group at The Sahlgrenska Center for Pediatric Ophthalmology Research.
An additional recent outcome of SWEDROP is the individualised risk prediction for an infant to develop ROP needing treatment, developed by Ann Hellströms research group at The Sahlgrenska Center for Pediatric Ophthalmology Research, now available online at www.digirop.com.

Thank you very much for the interview!

View more: 

• Further information about ROP by EFCNI 
• Retina.net, Germany (Deutsches Frühgeborenenretinopathie-Register)
• SWEDROP, Sweden
• WINROP, Sweden
• Acta Ophthalmologica (2016): The German ROP Registry: data from 90 infants treated for retinopathy of prematurity
• Acta Ophthalmologica (2014): Evaluation of new guidelines for ROP screening in Sweden using SWEDROP – a national quality register