The red reflex is a term used to describe the direct visualization of a child’s retina. The red reflex assessment is a non-invasive vital test used for detecting early warning signs of serious eye abnormalities such as glaucoma, cataracts, retinoblastoma (childhood eye cancer), retinal abnormalities, high refractive errors, and systemic diseases with ocular manifestation.
How Red Reflex Assessment Works
The red reflex assessment involves using the transmission of light from an ophthalmoscope through the normally transparent parts of the patient’s eye which include the cornea, crystalline lens, and vitreous humor.
The transmitted light reflects off the ocular fundus, back through the optical media through the aperture of the ophthalmoscope and it is imaged in the examiner’s eye. Any factor that blocks the optical pathway results in the abnormality of the red reflex.
Causes of the Red Reflex Abnormalities
An abnormal red reflex can be as a result of various factors such as:
- Mucus in the tear film
- Foreign bodies in the tear film
- Aqueous opacities
- Corneal opacities
- Vitreous opacities
- Iris abnormalities affecting the pupil
- Retinal abnormalities such as tumors
- High or unequal refractive errors (need for glasses)
Preparation for the Test
Before the test, a detailed history of the child will be taken which will include the child’s birth history, medical conditions, allergies, and family medical history. The child’s vital signs and weight will also be checked.
Prior to the test, the pediatric ophthalmologist will dilate the child’s pupils so as to allow for a better view of the eye. The eye drops are administered three times, with ten minutes intervals between the doses.
Once the pupils are dilated, the pediatric ophthalmologist will perform the assessment.
Performing the Red Reflex Test
The red reflex test is performed in a darkened room with the pediatric ophthalmologist holding a direct ophthalmoscope close to his/her eye and the power of the ophthalmoscope set close to 0. The light from the ophthalmoscope is then projected in the child’s both eyes simultaneously from approximately 18 inches away.
A normal red reflex is symmetric in character and should emanate from both eyes. An abnormal red reflex is characterized by a markedly diminished reflex, dark spots in the red reflex, asymmetry of the reflexes (Bruckner reflex), or presence of a white reflex.
However, the presence of mucus in the tear duct that is mobile and tends to completely disappear when blinking is an exception. Indications of an abnormal reflex are referred for further tests and treatment depending on the child’s age and the cause.
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