Introduction
Pseudostrabismus is an ocular condition in which the eyes appear to be misaligned. The morphological changes occurring in the face give an illusion of the eyes being misaligned despite the proper alignment of the eyes. However, both eyes point forward. It majorly occurs in three forms.
Is Pseudostrabismus a Common Condition?
The exact prevalence of pseudostrabismus is not known. Of all the three types, pseudoesotropia is the most common. Patients suffering from pseudostrabismus have a 12 % higher chance of contracting true strabismus later.
Different Forms of Pseudostrabismus
Pseudostrabismus primarily occurs in the following forms:
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Pseudoexotropia - Patients with pseudoexotropia have an outward alignment of the eyes.
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Pseudohypertropia - Both eyes appear vertically misaligned in pseudohypertropia.
What Are the Causes Linked to Pseudostrabismus?
Pseudesotropia is seen in infants with a wide nasal bridge and the presence of small epicanthic folds in the middle canthus region surrounding the eyes. Epicanthal folds are skin folds on either side of the lateral part of the nose that is directed inwards. Patients with a smaller distance between the two pupils also show esodeviation (inward movement of eyes). It occurs due to the face's morphology change, such as the size and shape of the orbits, globes, retrobulbar tissue, and volume.
A negative kappa angle also initiates pseudoesotropia. The Kappa angle is the difference between the pupillary axis and the visual axis. Pseudoexotropia, on the other hand, occurs due to hypertelorism (the distance between the two eyes is large). Diseases of the retina cause an ectopic shift of the macula (the back portion of the retina) temporally, stimulating exotropia. Retinopathy of prematurity also causes a positive kappa angle, eventually leading to pseudoexotropia. Pseudohypertropia is seen in facial asymmetry, where one eye appears higher than the other. It is caused because of the presence of a tumor on the orbital floor, retraction of the eyelid, or asymmetry of the eyelids.
What Are the Risk Factors for Developing Acquired Pseudostrabismus?
Risk factors responsible for pseudostrabismus include:
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Retinal pathologies in premature babies cause a temporal shift in the macula.
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Asians have a prominent epicanthal fold in the middle canthus region.
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Tumors of the orbit.
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Infections of the choroid and retina.
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Vertical asymmetry of the eyelids. It is present in conditions like Horner's Syndrome, thyroid eye disease, etc.
What Are the Clinical Presentations of Patients Suffering From Pseudostrabismus?
Pseudostrabismus is usually noted in infants and children during routine examinations.
Pseudoesotropia is more prominent when the child gazes sideways as the nasal sclera gets buried under the thick epicanthal fold. The feature of crossed eyes does not increase with fatigue. There is no actual movement of one eye inwards or outwards while the other remains stationary. The crossing of the eyes never worsens; it decreases with age.
Pseudostrabismus is more exaggerated when seen in photographs. The most prominent clinical sign that is present in patients suffering from pseudostrabismus is that there is no misalignment in the eyes when a flashlight is directed toward the pupil of the eyes.
How Are Patients Suffering From Pseudostrabismus Diagnosed?
The diagnostic procedure involved for pseudostrabismus includes history and a complete visual examination of the eyes. The patient's history, including the child’s birth weight, gestational period, health, history of any previous surgery for retinopathy, and the child’s first photograph, is acquired. Visual examination of the eyes includes visual, motor, and sensory function evaluations.
Age-appropriate visual acuity tests do the visual evaluation. Motor functions of the eyes are evaluated to differentiate them from the true strabismus. It is done using Hirschberg’s light reflex test and cover-uncover test. Additional prism adaptation and ocular muscle function tests are also conducted. Complete sensory function assessment is not possible in some children; instead, fixation preference of one eye using a vertical prism test is performed on them.
Diagnosis of Pseudostrabismus. A Quandary for Doctor?
Often, no apparent abnormal presentation clinically makes it difficult for the primary care physician and pediatrician to refer the patient to a specialist, who is often left undiagnosed.
Does Pseudostrabismus Need Treatment?
Pseudostrabismus does not require any treatment; it gets resolved completely as the child grows, and the epicanthal folds present near the nose get diminished. The patient's parents should be counseled about the temporary nature of the condition and encouraged to be in regular follow-ups for six to twelve months to rule out true strabismus. Also, parents should be aware that children suffering from pseudostrabismus are at a higher risk of acquiring true strabismus in their later life.
Which Conditions Share the Similarities With Pseudostrabismus?
The primary condition that needs to be ruled out before forming a confirmatory diagnosis of pseudostrabismus is true strabismus.
How to Differentiate Pseudostrabismus From a True Strabismus?
The easiest way to tell the difference between true and pseudostrabismus is to see a child’s flash photo. If the light is reflected from both eyes in the same place, the baby suffers from pseudostrabismus. Ophthalmologists can detect pseudostrabismus by performing a complete eye exam and checking for shortsightedness or farsightedness in a child.
Pseudostrabismus resolves by itself with age, thus making it easy to differentiate it from true strabismus, which persists through adulthood.
Is It Useful to Differentiate True Strabismus From Pseudostrabismus?
Differentiating pseudostrabismus from its true counterpart is essential, as if true strabismus is left untreated, it can cause vision loss.
What Is the Overall Outlook of Pseudostrabismus?
Overall, pseudostrabismus enjoys an excellent prognosis, with most cases showing complete resolution within two to three years of age. Pseudostrabismus with positive or negative kappa angle persists throughout life.
Conclusion
Pseudostrabismus is mostly a self-limiting condition of the eye characterized by the appearance of malalignment of the eyes. It primarily develops due to morphological changes in the child’s face while growing; hence, it resolves spontaneously with time. It is essential to differentiate it from true strabismus, which severely interferes with the normal visual development of a child.
