Did You Know?
The American Academy of Pediatrics (AAP) recommends that red reflex test must be conducted for every newborn before discharge from the nursery, and an infant with an abnormal or absent reflex must be referred to an ophthalmologist for an examination at the earliest.
One of the main vision-related tests―the red reflex test―is a screening test that must be conducted for the early detection of vision problems in newborns. This test involves the use of an ophthalmoscope, which is a lighted instrument that is used by ophthalmologists to examine the inside of the eye, including the retina and the optic nerve.
The test is conducted in a dimly-lit room, and the ophthalmoscope is held at a distance of 12 to 18 inches. During this test, light that is transmitted from an ophthalmoscope passes through the tear film, cornea, aqueous humor, crystalline lens, and vitreous humor (transparent parts of the human eye). As this light reflects off the fundus (back of the eye) and is transmitted back through a tiny opening in the ophthalmoscope, the ophthalmologist can see a magnified image of the structures at the back of the eye, which include the optic disc, retina, retinal blood vessels, macula, and choroid.
In case of healthy eyes where there is no obstruction in the optical pathway, red reflex is present, which means that a reddish-orange reflection of light from the retina would be observed. Absence of red reflex is indicative of certain serious eye conditions, which is why, this test is conducted in newborns to rule out vision-related problems.
Ophthalmoscopic Examination for Red Reflex
Red reflex is considered to be an effective test for the detection of abnormalities or opacities in the back of the eye or the visual axis. For accurate results, a direct ophthalmoscope that has a large-sized aperture should be used, as that would allow the doctor to focus on the face clearly and check and compare the reflection in both eyes simultaneously.
Normal Red Reflex
The test will be considered normal under the following circumstances:➠
The red or orange glow must be observed in both the eyes.➠
The reflection should be symmetrical in terms of color, intensity, and clarity.
The pediatrician should make a referral to an ophthalmologist in the following cases:➠
Opacities or white spots (leukocoria) are observed within the area of red reflex in one or both eyes➠
Dark spots are present in the region of red reflex➠
Red reflex is blunted on one side➠
Red reflex is absent➠
White reflex is present (retinal reflection)
The test must be conducted properly, as the pupils in infants can sometimes be small. Moreover, the infant might not keep the eyes open. In such cases, pupils might have to be dilated, provided the infant is older than 2 weeks. While observing the change in the color, the change in the level of pigmentation of the fundus in children from different ethnic groups should be considered. In case the reflection is abnormal or absent, and there is family history of retinoblastoma or cataract, the child should be taken to an ophthalmologist at the earliest.
Absent/Abnormal Red Reflex in Newborns
If the reddish-orange reflection of the light is not observed in one or both eyes, it implies that the red reflex is absent. This indicates the presence of an obstruction or abnormalities in the structures located at the back of the eye. In some cases, lack of symmetry in the red reflex might be indicative of unequal or high refractive errors. The contributing factors for an absent red reflex might include:Cataract
Cataract is an eye condition that is characterized by the clouding of the natural lens of the eye. It can affect one or both eyes. The natural lens is a clear part of the eye, which helps focus light or an image on the retina. Under normal circumstances, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain.
The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image would be blurred. This condition can also be present at birth. However, the cataract in newborns might be so small that it might not affect the vision. Thus, checking red reflex is extremely important to rule out cataract.Retinal Abnormalities
Retinoblastoma refers to a rare type of eye cancer that might affect children before the age of 5 years. The cancer affects the retina, which is the specialized light-sensitive membrane at the back of the eye. Leukocoria, which refers to the whiteness in the pupil, is one of the most early signs of retinoblastoma. This can be detected through the red reflex test, or even observed in photographs that have been taken with a flash. It is believed that retinal detachment (detachment of retina from the underlying tissue layer) could be responsible for the absence of red reflex.
Retinal detachment could occur in individuals affected by Coat's disease, where dilated and abnormally twisted blood vessels in the eye hamper the normal flow of blood. Leakage of fluid from the blood vessels might give rise to a buildup of fatty material into the retina. Retinal detachment can occur when there is a large buildup of fatty material. In children affected by Coat's disease, a yellowish glow is observed during direct ophthalmoscopy.Refractive Errors
For us to be able to see properly, light rays are bent (refracted) while they pass through the cornea and the lens. Thereafter, the light is focused on the retina, which is a light-sensitive membrane covering the back wall of the eyeball that is continuous with the optic nerve. The retina converts the images into electric signals, and sends them to the brain through the optic nerve. The brain then interprets these messages into the images we see. Refractive errors occur when one has a problem in focusing due to the irregular shape of the cornea or the length of the eyeball. High refractive errors could sometimes cause an asymmetrical red reflex. Sometimes, both eyes might have a red reflex; however, there might be difference in the level of brightness. This could be indicative of anisometropic amblyopia that occurs due to different refractions.Strabismus
Strabismus, which is commonly referred to as crossed eyes, is an eye condition that is characterized by abnormal alignment of one or both eyes. This condition could occur in the event of problems related to eye muscles, control center in the brain that is involved with movements of the eyes, or the nerves that transmit information to the muscles. The cause of congenital strabismus, which means strabismus that occurs at or shortly after birth, is not known. It is believed that family history could put one at a risk. Conditions such as retinoblastoma, retinopathy of prematurity, cerebral palsy, etc., could be associated with strabismus in children.
On a concluding note, both cataract and retinoblastoma are the most common causes of absent red reflex in newborns. However, the differential diagnosis also includes the presence of foreign body in the tear film, aqueous, vitreous, or corneal opacities, or iris abnormalities that affect the pupil. This test must be conducted during the first 2 months by a pediatrician. An examination by an ophthalmologist is essential for infants who are in the high-risk groups. Once the underlying cause has been determined, the treatment options can be ascertained.Disclaimer
: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.