The term 'red reflex' refers to the reddish-orange glow or the
reflection of light that is observed from the eye's retina during direct
ophthalmoscopy. This Buzzle write-up provides information on the causes
of the absence of red reflex in newborns.
Meaning of absent red reflex in newborns
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.
Ophthalmoscopic examination
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Ophthalmoscope
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.
Red reflex
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.
Human eye
Cataract
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.
Damaged optic nerve and retinal detachment
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.
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