“What are so mysterious as the eyes of a child?” - Phyllis Bottomed
In 1892, Smith observed that the corneal light reflex was more clearly discernable against the bright background of the pupillary light reflex using the coaxial illumination of an ophthalmoscope. Worth found that the pupil in the deviating eye appeared larger and the fundus reflex brighter as compared to the fixing eye. Based on these observations, Brückner described in German literature in 1962 a simple screening test to assess the symmetry of binocular fixation by comparing the intensity and quality of red reflex simultaneously in both eyes using the direct ophthalmoscope, which he called “pupillary transillumination”. Tongue and Cibis popularized it eponymously as the Brückner’s test. Various aspects of the red reflex test have been extensively studied over the years, beyond what Brückner originally intended it for, and it is currently recommended as an inexpensive tool for rapid opportunistic screening of the newborn by the pediatricians and other healthcare professionals for common sight-threatening entities such as asymmetrical refractive error, squint, congenital cataract, corneal opacities, and retinoblastoma and other simulating causes for leukocoria. The joint policy statement by the American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus, the American Academy of Ophthalmology, and the American Association of Certified Orthoptists recommends red reflex test “as a component of the eye evaluation in the neonatal period and during all subsequent routine health supervision visits” and provides succinct recommendations and outlines indications for referral to an ophthalmologist [Table 1]. The red reflex test is also a part of the Government of India guidelines for universal eye screening in the newborn. The World Health organization, however, does not include it in its primary care mandates. Fig. 1 shows the common findings seen on the red reflex test and its implications.
Is Red Reflex Test Reliable?
In a recent meta-analysis, Subhi et al. analyzed the diagnostic value of the red reflex test without pupillary dilation versus standard diagnostic examination with pupillary dilation in 8713 infants from five unique studies. The sensitivity of the red reflex test for ocular diseases, in general, was a low 7.5% but with an impressive specificity of 97.5%. Sensitivity (17.5%) was better for ocular pathologies that required medical or surgical intervention. The negative predictive value was 99.2%, implying that 99 of 100 infants with a normal red reflex will not have a severe ocular disease. The positive predictive value was 7.7%, indicating a 7-fold higher risk of severe ocular disease in infants with an abnormal red reflex. In a large meta-analysis published in this issue of Indian Journal of Ophthalmology, the authors seem to confirm the low sensitivity (23%) and high specificity (98%) of the red reflex test but show that the test is excellent for the detection of anterior segment anomalies (99.2%) as compared to disorders of the posterior segment (14.1%).
Is Red Reflex Test Useful?
There are detailed guidelines for age- and risk-stratified pediatric eye evaluation. However, in a real-world setting, with sight and/or life-threatening conditions such as congenital cataracts and retinoblastoma being rare, screening of all neonates by an ophthalmologist or by a dilated fundus examination or wide-field imaging may not be cost- and time-effective and may overwhelm the healthcare system. In this context, the utility of the red reflex test as a simple and inexpensive general neonatal screening tool cannot be undermined. Real-world data shows that congenital cataract is diagnosed earlier in Sweden (where a red reflex test is performed on all neonates) as compared to socioeconomically similar neighboring Denmark (where a red reflex test is not routinely used). An undilated red reflex test can detect a posterior polar tumor, while a dilated red reflex test may help discern a peripheral tumor as well, thus making the early diagnosis a possibility. Squint would be very evident, but an astute observer may be able to pick up an odd child with an asymmetrical refractive error.
Are There Better Screening Tools?
Seemingly better and inexpensive screening tools are emerging as potential alternatives to the classic red reflex test. A recent study from Tanzania showed sensitivities of 97.6% for CatCam, 92.7% for Arclight, 90.2% for PEEK retina as compared to only 7.3% for torchlight in the detection of cataract and retinoblastoma with an ophthalmologist’s examination as the gold standard. Estimated specificities were 100% for CatCam, 96.7% for Arclight and 86.7% for PEEK retina. Smartphone-based infrared imaging for cataracts and App-based tools for retinoblastoma detection are already available. TrackAI project with a novel Device for an Integral Visual Examination (DIVE) plugging onto smartphone-based artificial intelligence algorithms is an exciting new development.
Future Seems Bright
While the classic red reflex test performed in an ideal clinical setting by a trained observer continues to be the basic screening tool for neonatal eye screening, escalation to a robust age- and risk-stratified screening strategy, where indicated, may help optimize the screening net. Future seems pregnant with possibilities of bright and technologically driven mass screening tools.
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