With the invention of the ophthalmoscope in 1851 came the red-reflex test, which has since been used for the early detection of paediatric eye disease. DR SANDRA STAFFIERI examines its effectiveness.
In keeping with the American Academy of Pediatrics (AAP) guidelines, there is broad agreement that all newborns in Australia should be screened using the red reflex test in the neonatal period. This examination is listed in all the infant health record books and is usually performed by the obstetrician, paediatrician or general practitioner.
Whilst ethnic variations may be confusing to the inexperienced observer and can predispose to false positives, sufficiently low false-positive rates of between 2% and 0.0006% still make red-reflex screening a worthwhile test.
The efficacy of red-reflex screening to detect congenital cataract is well documented, although some studies have demonstrated a failure of the neonatal screening to detect this disease. It is possible that the examiner remains inexperienced in performing the test, or it is not done at all despite recommended guidelines. Indeed, reviews of red-reflex screening in New Zealand identified self-reported deficiencies in knowledge and skills of the providers completing the screening.
Although there is a consensus that neonatal red-reflex screening in an Australian population should continue to be mandated, no studies evaluating its effectiveness have been reported and its limitations should be kept in mind.
Does it do what it is supposed to?
Although demonstrated as a highly sensitive test for the detection of anterior segment disease, its sensitivity for posterior segment disease is reportedly less than optimal. In a large Chinese cohort of 7641 neonates, Sun and co-workers (2016) found the neo-natal screening of the red-reflex test was highly sensitive for detecting anterior segment abnormalities (99.6%, CI 97.1-100%) but not for detecting posterior segment pathologies, including retinoblastoma (4.1%, CI 3.3-5.1%).
Similarly, in a large, prospective cohort US study comparing the red-reflex examination to wide-angle fundus digital imaging, Ludwig and colleagues found no posterior segment pathologies were identified in 202 newborns (2018).
Moreover, in Abramson and colleagues’ (2003) retrospective report of 1,831 cases of retinoblastoma, only 8% of children presented following routine ocular examination conducted by a paediatrician following AAP guidelines.
Have we got it right?
The technique used to examine the red reflex may limit its efficacy. According to the most current AAP recommendations, the red-reflex test should be performed in the primary position, in a darkened room without pharmacologic dilatation. Adhering to the technique as outlined, anterior segment anomalies will continue to be identified. However, smaller, peripheral retinoblastoma may be missed due to their location, or a small pupil reducing the field of view.
Using a model eye and different-sized discs (replicating retinoblastoma tumours) observed through an 8- or 3-mm sized pupil, (simulating a ‘dilated’ and ‘undilated’ pupil respectively), Li and colleagues (2010) demonstrated the technical limitations of the red reflex specifically for detecting retinoblastoma. Pupil dilatation, tumour size and location in the retina were all identified as key factors determining the sensitivity of the red-reflex test. Most importantly though, they demonstrated that it was easier to detect simulated retinoblastoma when the red reflex was performed obliquely (96%, CI 93-98%) as opposed to the traditional primary, ‘straight ahead’ position (<48% CI 39-57%).
Pupil dilatation as a predictor of tumour detection using the red-reflex test has been corroborated by Canzano and Handa (1999), who recommended pupil dilatation prior to examining the red reflex when leukocoria is suspected. Unless the presenting complaint is leukocoria or strabismus, pharmacologic dilatation may not be practical in the setting of red-reflex screening. This could be offset by modifying the technique to include oblique viewing, as well as ensuring a darkened room to allow for natural dilatation of the pupils.
Performing a screening test once for disease (as in Victoria) that can arise at any time along the continuum of child development is problematic. Just because significant ocular disease is not evident at birth, that does not mean it will not develop. This is particularly relevant for cataract and retinoblastoma. Hence, educating parents to recognise abnormalities in the red reflex observed in photographs is critical.
The appearance of the much-maligned red reflex in family photographs has spawned technologies to eradicate its appearance. This negative messaging can result in missed opportunities for early diagnosis of disease.
The red reflex has been embraced as a clinically important assessment for children. However, its limitations must be recognised and addressed to counter the false sense of security it provides.
ABOUT THE AUTHOR:
Dr Sandra Staffieri is a Clinical and Research Orthoptist with over 35 years’ experience working at the Royal Children’s Hospital, Victoria. She has developed the unique role of Retinoblastoma Care Co-ordinator in the Department of Ophthalmology and is affiliated with the Centre for Eye Research Australia, University of Melbourne.
ORTHOPTICS AUSTRALIA strives for excellence in eye health care by promoting and advancing the discipline of orthoptics and by improving eye health care for patients in public hospitals, ophthalmology practices, and the wider community. Visit: orthoptics.org.au