Bright eyes ahead: mastering red reflex screening

Abstract

Aim: The red reflex test (RRT) is a straightforward, non-invasive screening tool introduced by Brückner in 1962, primarily designed to assess non-cooperative patients. It assesses the reflection of light from the choroid through the transparent ocular media, including the cornea, aqueous humor, lens, and vitreous body. While straightforward in concept, achieving accurate and reliable results requires overcoming several practical challenges.

This review aims to provide practical guidance for clinicians to refine their technique and improve the effectiveness of the RRT for early detection of vison- and life-threatening conditions, such as retinoblastoma.

Methods: A narrative literature review was conducted to explore relevant sources on maternal and newborn care, as well as pediatric ophthalmic screening. The literature search was performed using PubMed and official WHO bulletins, during 2024, December 1-31. Studies and guidelines were selected based on their relevance to the topic. The extracted references include recommendations from WHO, national healthcare programs, and significant research articles in the field.  

Results: Performing the test: The clinician should begin by positioning themselves approximately 1 meter from the patient, adjusting this distance if the child is nervous or uncooperative, and gradually moving back to the standard 1-meter position. At this distance, using a direct ophthalmoscope, both pupils are illuminated simultaneously, enabling a direct comparison of the red reflexes. When both eyes simultaneously fixate and focus on the ophthalmoscope light, the pupils constrict, the corneal light reflexes align centrally, and the red reflexes appear noticeably darker. The most frequent reason for an absent red reflex is pupil constriction. Afterward, a monocular alternating inspection should be performed at a distance of approximately 40 cm for a more thorough evaluation.

Common Problems and Solutions:

1. Sharpening the Image

Proper Positioning: Hold the ophthalmoscope close to your eye, set the lens power to "0," and focus the patient's pupil.

Refractive Adjustments: Clinicians with refractive errors can dial their corrective power into the ophthalmoscope to achieve a clear image, avoiding reliance on spectacles. A practical method is to look through the peephole and adjust the lens dial of the ophthalmoscope until a sharp, focused image is visible.

1. Maximizing Pupil Size

 Darkened Environment: Conduct the test in complete darkness to facilitate pupil dilation.

Optimal Light Settings: Adjust the ophthalmoscope's light beam to use the smallest possible circle of light.

Dilating Drops: If necessary, apply pupil-dilating drops to improve the visibility of the reflex. The recommendations for pharmacological pupil dilation are: (1) children younger than 9 months: a combination of 0.25 % cyclopentolate and 2.5 % phenylephrine about 15 minutes before examination. Atropine should be avoided; (2) children older than 9 months: tropicamide 1 % and/or phenylephrine 2.5 % 15 minutes before examination. In infants, pupils respond well to mydriatics, but sporadic incidents have been reported with all commercially available drops, including sympathomimetics (phenylephrine) and anticholinergics (tropicamide).

1. Encouraging Eye Opening

Distraction Techniques: Have someone positioned behind you to engage the child with toys or lights, helping to direct their gaze naturally while you perform the examination.

Ritter's Position for Infants: Hold infants at a 45-degree angle, supporting their thorax while gently jiggling their bottom. This technique utilizes a primitive reflex, observed in neurologically healthy children up to six months of age, to facilitate spontaneous eye opening.

1. Expanding the Field of View

 Peripheral Retina Assessment: While a co-axial alignment is effective for evaluating the red reflex, it may overlook small peripheral ocular pathologies. To address this, the pediatrician should perform the RRT from varying angles, incorporating oblique views to thoroughly assess the nasal and temporal retina in addition to the standard straight-on examination of the fundus.

1. Interpreting Results

Normal Reflex: Symmetrical, bright red reflexes in both eyes indicate healthy ocular media.

Abnormal Reflexes: Look for asymmetry in color, brightness, or size, as well as the absence of a reflex, white reflexes, or dark spots, all of which may indicate serious conditions such as cataracts, strabismus, retinal anomalies, and retinoblastoma.

1. Adjusting Distance

Refractive Error Insight: Increasing the distance can amplify refractive disparities, making conditions such as anisometropia more apparent.

Conclusion: The red reflex test is a vital, easy-to-perform examination that enables the early detection of vision-threatening and life-threatening ocular conditions. Modern challenges, such as the diminished visibility of the red reflex due to "red-eye remover" technology in digital cameras, underscore the importance of manual RRT. By implementing the outlined tips and tricks, clinicians can overcome common challenges, optimize their examination approach, and ensure timely referral for children with abnormal findings. This simple yet powerful test underscores the importance of vigilant screening in pediatric eye care.