Introduction
Megalopailla simply refers to the enlarged optic disc or optic nerve head. The optic nerve is the second cranial nerve of all twelve nerves. This nerve has a crucial role in transferring and conveying visual information from a sensitive layer present at the back of the eye called the retina to the brain, helping with the perception and processing of visual images.
Damage or injury to this nerve could result in vision impairment or total vision loss. The optic nerve incorporates several parts from its extension from the eye to the brain. This includes the optic nerve head, intraocular portion, nerve sheaths, and optic chiasm. The optic nerve head or disc is the point or spot where the nerve exits the back region of the eye. The optic nerve head is also called the blind spot since it lacks photoreceptors (light-sensitive cells). Here is where the nerve fibers from the eye's retina join together.
What Is Megalopapilla?
Megalopapilla is a non-progressive, rare eye disorder typically characterized by an enlarged optic nerve head. The optics nerve head or optic disc refers to the exit spot for ganglionic cells that leave the eyes. The diameter of the optic nerve head might enlarge to a greater diameter, transcending 2.1 millimeters. Megalopapilla possesses no other abnormalities or discrepancies in the optic nerve and eye morphology. Megalopapilla is a congenital anomaly characterized by an abnormal optic disc shape or enlarged optic nerve head. This condition could mimic glaucomatous signs concerning the optic nerve, occurring in one or both eyes. This condition has been mostly reported in people with congenital glaucoma (a range of eye disorders causing vision loss and complete blindness due to damage to the optic nerve), pulverulent cataract (a kind of congenital cataract that presents with the cloudiness in the lens of the eye), and basal encephalocele (a rare congenital malformation).
What Is the Etiology of Megalopapilla?
Megalopapilla is a benign eye disorder with an unknown etiology and causative factor. The mechanism behind this uncommon condition has yet to be determined or explained. However, this condition is usually a variant of normal morphological parameters. There is a proposed or hypothetical mechanism saying that there can be a modified optic axonal migration during the early stage of embryogenesis in infants with suspected basal encephalocele. Certain findings show that megalopapilla also possesses a hereditary determinant, while it has been reported in twin children and their paternal grandparents.
What Are the Risk Factors of Megalopapilla?
There are no known risk factors or causative determinants for megalopapilla. However, many individuals with this condition have been reported with an enlarged optic disc of diameter exceeding 2.1 millimeters. Megalopapilla might lead to physiologically enlarged blind spots in certain cases. Though this feature might represent glaucomatous changes on certain diagnostic procedures, megalopapilla has no loss in optic nerve fibers and thickening of the retinal fiber layer. Hence, this condition is a false glaucomatous disorder, an example of physiologic cupping.
What Are the Types of Megalopapilla?
There are two types of megalopapilla based on the involvement of the number of eyes.
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Type 1: This is the most common form of megalopapilla. This is usually bilateral, having the normal configuration of the optic cup (a cup-like white spot seen in the center of the optic disc).
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Type 2: This type is typically unilateral and associated with the upward displacement of the optic cup.
What Are the Clinical Features of Megalopapilla?
The clinical features of the megalopapilla include the following.
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The diameter of the optic disc or optic nerve head exceeds 2.1 millimeters.
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An increased cup-to-disc ratio.
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Only the optic disc seems abnormal.
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The optic disc's sharpness, color, and rim volume will be unchanged.
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The intraocular pressure and blood circulation would be normal.
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There is an enlarged blind spot, otherwise normal visual field.
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Visual acuity can be normal or decreased on an occasional basis.
How Is Megalopapilla Diagnosed?
The doctors perform an extensive ophthalmologic treatment examination. The other diagnostic procedure that the healthcare professionals recommend to confirm the diagnosis of megalopapilla includes the following.
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Ophthalmoscopy: Ophthalmoscopy, also referred to as fundoscopy, is a diagnostic test that allows visualizing the fungus (back region of the eye) and other eye structures through an ophthalmoscope. Here, a large size or increased diameter of the optic disc can be seen in the ophthalmoscopic examination.
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Optical Coherence Tomography: Optical coherence tomography (OCT) is a non-invasive imaging technique that represents an in vivo and cross-sectional view of the sensitive eye layer called the retina. Though this approach does not show the disc size, OCT is usually used to differentiate between healthy and glaucomatous eyes having an enlarged optical disc.
As the clinical features of megalopapilla and glaucomatous optic disc are similar, it is important to differentiate pseudo-glaucomatous disorders like megalopapilla from normal tension glaucoma.
What Is the Management of Megalopapilla?
It might be risky and challenging to provide treatment for megalopapilla. The general risk and complications of common eye problems apply to individuals with megalopapilla. This is because the anomalous or abnormal optic nerve might contribute to a diagnostic challenge for other eye problems affecting the optic nerve, including chronic open-angle glaucoma. The other routine visual field and appropriate techniques are considered in managing megalopapilla.
What Is the Prognosis?
The prognosis for individuals with megalopapilla is often favorable in terms of vision and overall eye health. While the megalopapilla itself does not typically cause visual impairment, it may be associated with certain conditions like optic nerve drusen or other optic nerve anomalies. In such cases, the prognosis depends on the specific underlying condition and its impact on vision. Regular ophthalmic examinations are essential for monitoring any potential changes in the optic nerve head or associated eye health issues. While the megalopapilla itself may not necessitate treatment, addressing any related conditions and maintaining routine eye care can contribute to a positive prognosis for affected individuals.
Conclusion
Megalopapilla is an extremely rare eye condition usually present right from birth. It can sometimes be found in the hereditary factor, passing from one generation to another. The marked clinical feature of the megalopapilla is an enlarged optic nerve head. The optical nerve head seems irregular with an enlarged cup but is associated with the standard visual field and intraocular pressure.
