Corneal degenerations. They are a rare group of slowly progressive bilateral degenerative disorders that usually appear in the second or third decades of life. Some are hereditary, others a consequence of inflammatory eye disease, and others are of unknown cause.
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- 1 Types of corneal degenerations
- 1 Senile bow
- 1.1 Symptoms
- 1.2 Signs
- 2 Vogt White Limbic Halo
- 3 Calcium band keratopathy
- 3.1 Etiology
- 3.2 Symptoms
- 3.3 Signs
- 4 Spheroidal degeneration
- 4.1 Etiology
- 4.2 Symptoms
- 4.3 Signs
- 5 Salzmann’s Nodular Degeneration
- 5.1 Features
- 6 Lipid degeneration
- 6.1 Features
- 6.2 Symptoms
- 7 Terrien marginal degeneration
- 7.1 Features
- 7.2 Symptoms
- 8 Groove degeneration (Furrow degeneration)
- 9 Hassall-Henle bodies
- 10 Polymorphic amyloid degeneration
- 1 Senile bow
- 2 Source
Types of corneal degenerations
- Senile bow.
- Vogt White Limbic Halo.
- Calcium band keratopathy.
- Spheroidal degeneration.
- Salzmann’s nodular degeneration.
- Lipid keratopathy.
- Terrien marginal degeneration.
- Furrow degeneration.
- Hassall-Henle bodies.
- Polymorphic amyloid degeneration.
Peripheral, bilateral, benign, very common degeneration that occurs at any age, but more frequently between 50 and 60 years and in the black race. Below 40 years it can be associated with hyperlipoproteinemia with high serum cholesterol. It is occasionally seen as a congenital anomaly (juvenile arch) and is not associated with serum lipid abnormalities.
- Opaque gray ring, beginning at the upper and lower poles and encompassing the entire corneal circumference, 2 mm in diameter, which leaves a clear space between the outer edge and the limbus.
- The unilateral arch is associated with carotid artery disease or ocular hypotonia.
Vogt White Limbic Halo
Degeneration characterized by peripheral white opacities, affecting the temporal and nasal cornea. There are two ways:
- Type I: Narrow, concentric, superficial, with a clear interval between it and the limbus, with chalk-like opacities and small light areas that resemble Swiss cheese.
- Type II: consists of small, white deposits, similar splashes or mottled like needles. They are seen in older patients and there are no clear gaps between the arch and the limbus.
Calcium band keratopathy
It is a superficial calcium degeneration that affects the Bowman’s membrane with calcium hydroxyapatite deposits .
- Chronic (usually inflammatory) eye diseases such as: uveitis (child), interstitial and superficial keratitis , and Ptisis bulbi.
- Hypercalcemia caused by hyperparathyroidism, vitamin D intoxication, milk alkali syndrome, sarcoidosis.
- Hereditary (hereditary primary band keratopathy).
- High serum phosphorus with normal serum calcium (kidney failure).
- Chronic exposure to mercurial vapors.
- Silicone oil instillations in an aphakic eye.
- Decreased vision.
- Foreign body sensation.
- Dusty peripheral deposits in Bowman’s membrane, with clear spaces between them and the limbus. When they coalesce they form a horizontal interpalpebral band of dense calcium plaques.
- Other causes: corneal deposits of brown urates.
It has also been named corneal elastosis, keratinoid degeneration, keratopathy in climatic drops, Bietti’s nodular dystrophy, proteinaceous degeneration, labrador keratopathy.
- Combined effects of ultraviolet radiation.
- Genetic predisposition.
- Decreased vision.
- Foreign body sensation if it spreads to the cornea.
- Spheroidal amber deposits in superficial stroma (sometimes in conjunctiva).
- It spreads on the cornea producing non-calcium band keratopathy. More common in males.
Salzmann’s Nodular Degeneration
Inflammatory corneal degeneration that can develop after chronic keratitis, trachoma, or phlictenulosis. It can be associated with recurrent corneal erosion syndrome.
Presence of bluish-white or bluish-white subepithelial nodules, often developing circularly in the central or paracentral part of the cornea and in the terminations of the vessels of a pannus . It generally affects the superficial cornea that involves the stroma, the Bowman’s layer, and the epithelium.
It occurs after prolonged corneal inflammations (eg, trachoma, herpes simplex disciform and herpes zoster keratitis), which is why it is described as secondary lipid keratopia. When there is no history of corneal disease, it is called primary lipid keratopathy.
Collection of cream or yellow lipids that contain cholesterol, neutral fats, and glycoproteins deposited on the superficial or deep cornea, commonly in an area of vascularized corneal scars. The epithelium is secondarily involved.
- Blurry vision.
Terrien marginal degeneration
It is a slowly progressive peripheral, non-inflammatory, unilateral or asymmetrically thinning of unknown cause. 75% of patients are male and commonly occur in the third or fourth decades of life.
Initially, there are yellowish-white, pinpoint stromal opacities associated with mild superficial vascularization, beginning at the top of the cornea and separated from the limbus by a transparent zone. Delayed thinning leads to the formation of a circumferential peripheral channel, the external slope of which is gradual; while the central part rises abruptly, delimited by a grayish-white line or it may show yellowish-white lipid deposits. The canal epithelium is intact and does not stain with fluorescein.
- It is usually asymptomatic.
- Occasionally foreign body sensation.
Groove degeneration (Furrow degeneration)
In adults it presents the appearance of a thinning in the interval of a senile arch. There is no inflammation, vascularity or tendency to perforation, vision is rarely affected, although astigmatism may occur. The epithelium is intact and does not require treatment.
They are wart-like growths on the peripheral portion of Descemet’s membrane that protrude into the anterior chamber and represent a normal change with age, increasing in number. They are visible only to biomicroscopy and endothelial microscopy.
They are characterized by being pathological when they appear in the central cornea, and are then referred to as guttate cornea. If central guttas are associated with progressive epithelial and stromal edema, they are called Fuchs endothelial dystrophy.
Polymorphic amyloid degeneration
Corneal opacities that appear as starry mottling in the middle and deep stroma, or in the form of irregular filaments. Both forms can appear together, but one of them generally predominates.
These deposits (amyloid) are generally axial, polymorphic, filamentary, light gray in color, and translucent at backlight. Visual acuity is generally normal, and there is sometimes an association with systemic amyloidosis.