Feasibility of Nurse-led Retinal Imaging for Retinopathy of Prematurity Screening Employing the Optos California

Retinopathy of Prematurity (ROP) is the major cause of blindness in babies who are born early i.e. premature (defined as those born at less than 37 weeks' gestation). All premature infants are at risk of developing ROP and are therefore routinely screened for the condition. With improvements, it has become one of the few preventable causes of childhood blindness, and recent reports suggest that most babies are saved from sight loss with proper screening and treatment. As neonatal care gets better, more premature babies are surviving and the need for ROP screening is increasing all over the world: about 8200 babies need screening in the UK each year. Very few babies need treatment - less than 2% in the UK. At the Royal Derby Hospital (RDH), about 4 to 5 infants are screened each week, with only 1 to 2 needing treatment per year.

The international classification of ROP describes ROP by its severity or stage (Stages 1-5), location by zone (I-III), extent by clock hours, and by the presence of pre-plus and plus disease. The aim of screening is to find out if the baby has any of these so that treatment can be done if needed. All babies born before 32 weeks or at less than 1500 g birth weight must have regular screening. For those born at <27 weeks gestation, the first ROP screening examination should be undertaken when at 30 to 31 weeks corrected gestational age while for babies who are more mature at birth, it is done between 4 to 5 weeks of actual age. Follow-up examinations should be performed every 1 to 2 weeks thereafter until the ophthalmologists (eye doctors) can see that the retina is fully matured. If there are signs of ROP, examinations should be performed more frequently, either weekly or twice a week.

All ROP screening examinations are currently done by a highly trained ophthalmologist using binocular indirect ophthalmoscopy (BIO), which is considered the gold standard method. The retinal findings are seen and drawn by hand in the patient's notes. These screening examinations are time-consuming for the ophthalmologist, and costly for the medical system as they need the ophthalmologist to be physically present and to do the screening. This makes it difficult for babies in remote hospitals or settings without trained ophthalmologists to have ROP screening. To reduce this difficulty several groups have developed cameras that can take pictures of the retina. The pictures can then be transferred to ophthalmologists who can diagnose and grade the ROP remotely.

The most common imaging system used for ROP screening is the RetCam (Clarity Medical Systems, Pleasanton, California, USA). The RetCam imaging system, a hand-held camera, is connected by a fiber optic cable to an electro-optical box housed in a movable cart. To take images with RetCam, the babies pupils have to be dilated (opened up) by using medicines and local painkillers. The eyelids are held open with a lid speculum and the camera probe is applied with a contact lens gel such that it is touching the front of the eye, over the open pupil. RetCam images are not able to include the whole of the back of the eye in one picture and therefore multiple images have to be taken. This takes time and effort from highly-skilled imagers. Also, the picture quality is not good if the pupil is not opened properly or if there is some obstruction in the way such as blood in the eye. As the camera has to touch the eye, it can hurt the eye and make the baby uncomfortable such as by stimulating eye nerves that cause the heart to slow down and lower the baby's blood oxygen levels. Too much pressure on the eye can also change the picture and make the diagnosis difficult.

More recently, a new camera, the Optos ultra-widefield retinal-imaging device (Optos PLC, Dunfermline, Scotland, UK) has been used to take and store pictures of different stages of ROP in babies. This camera has a specialised mirror to capture pictures that contain details of nearly all of the retina in a single photo. It is quick, the complete single photo can the taken in a quarter of a second. In addition, it can take pictures without touching the baby's eyes so there is no risk of damage to the eye. Thus, the Optos camera has many advantages over the RetCam.