What is sclerocornea?

Sclerocornea
Definition: Sclerocornea is defined as a non-progressive scleralization of the cornea in which the peripheral cornea and sometimes the entire cornea is opacified by thick collagen bundles and vascularization without antecedent inflammation.
Incidence/ Prevalence: The incidence in males and females is equal and 90% of cases are bilateral. Although the prevalence and incidence seem to elude the current literature, 1.4 % of randomly selected hospitalized eye patients had this condition (Reference 1).
Etiology: Approximately one half the cases are stated to be familial; autosomal dominant and recessive patterns of inheritance have been described. The other ½ of cases are sporadic.
Clinical Findings: The most common ocular association is cornea plana, found in 80% of cases. Keratometry reveals low values between 20 and 39 D. The limbus or corneal scleral sulcus is usually poorly defined, with superficial vessels extending from sclera, episclera, and conjunctiva to traverse into part or all of the cornea. Visual symptoms are dependent of the associated corneal flattening and of course whether the visual axis is affected by scleralization. Associated ocular abnormalities include aniridia, Axenfeld’s anomaly, cataract, coloboma, esotropia, glaucoma, microphthalmos, posterior embryotoxon, Rieger’s anomaly, and strabismus. Sclerocornea has been associated with facial anomalies, mental retardation, deafness, and cerebellar anomalies. Sclerocornea has been associated with a number of syndromes including Dandy-Walker, Hurler, Hallermann-Streiff and many others.

Histopathology: The anterior stromal collagen fibrils are irregularly arranged (number 1) and markedly thickened (3-6 times normal thickness). Cornea and sclera are difficult to distinguish. The collagenization is more prominent anteriorly (number 1) and dissipates posteriorly (number 2). Blood vessels (arrows 3) are seen in the superficial stroma. The pathology may be confined to the periphery with various degrees of central involvement. In the trichrome stained section one sees a wedge of scleralization (arrow 4) adjacent to the more central area (number 5). Bowman's layer is absent (arrow 6) as may be Descemet's membrane in the affected area. Critical to the diagnosis is the absence of inflammation, differentiating this entity from stromal keratitis. Note the complete absence of inflammatory cells in these photomicrographs.
Treatment: Penetrating keratoplasty has been performed for central corneal involvement but some authors feel the visual prognosis is probably not sufficient to warrant the procedure.
Prognosis: If the process is confined to the periphery, vision may be minimally affected. With success defined as graft clarity, the rate of success of penetrating keratoplasty is about 50% for sclerocornea (Ref 2).
Reference:
1. Ozeki H et al. Japanese Journal of Ophthalmology 1997:41:422-425.
2. Michaeli et al: J Pediatr Ophthalmol Strabismus. 2005;42:34-44.

What is Peters' anomaly of the cornea?

Peters' Anomaly of the Cornea
Definition: Peters' anomaly can be defined as a congenital corneal central opacity associated with a posterior defect in Descemet's membrane and endothelium. Two types have been defined.
Type 1 is unilateral, characterized by a central or paracentral corneal opacity with iris strands that arise from the iris collarette and attach to the cornea.
Type 2 is bilateral in 60% of the cases and shows lens adherence to the posterior cornea due to lack of separation from the lens. This finding is associated with cataract.
Incidence/Prevalence: rare
Etiology: Most cases are sporadic, yet both autosomal recessive and dominant modes of inheritance are reported. Peter’s anomaly is considered an alteration of the migration of waves of neural crest. Reported chromosomal anomalies include ring chromosome 20, trisomy 13, and partial deletion of the long arm of chromosome 11. Mutations occur at the PAX 6 locus on chromosome 11p13 in some Peters' anomaly patients. The anomaly has been reported as a feature of fetal alcohol syndrome.
Clinical Findings: Initially, a defect in corneal endothelium and Descemet's membrane is present, often with marked corneal edema. The edema may extend well beyond the defect giving rise to the central leukoma. A doughnut pattern of the congenital leukoma is highly suggestive of Peter's anomaly (white arrows numbers 1). Over time the surrounding endothelium covers the defect and produces new basement membrane. The edema regresses only to leave the corneal opacity. 50% of cases of Peter’s anomaly may be associated with a variety of ocular abnormalities including: bilateral glaucoma, sclerocornea, corectopia, iris hypoplasia, anterior polar cataract, iris corneal adhesion, keratolenticular touch, microcornea, aniridia, chorioretinal coloboma, iris coloboma, persistence and hyperplasia of the primary vitreous, microphthalmos, and optic nerve hypoplasia.
Systemic abnormalities associated with Peter’s anomaly include craniofacial dysostosis, hydrocephalus, pulmonary hypoplasia, cleft lip and palate, cardiac, and GU malformations.
Histopathology: The key findings are iris stromal fibers that join the collarette (arrow #2) and central cornea, in combination with an absent Descemet’s membrane and endothelium in the central cornea (arrow number 1 and black arrow 3, and number 4) as well as at sites of irido-keratic adhesion. The cornea may appear to have a divot taken from the posterior surface (posterior keratoconus, number 4) . Bowman’s layer may appear to be thicker than normal (black arrow number 5 and lighted arrow below in higher magnification, PAS stained section). Note the clear, branching, subtle channel at the lighted arrow, which is where a corneal nerve is fortuitously captured crossing the thickened Bowman's layer!
Treatment: Penetrating keratoplasty is often performed to correct the leukoma in bilateral cases. However, some authors contend that cases in which the fellow eye is normal do not warrant surgery.

What is conjunctival amyloidosis?

Primary Amyloidosis of the Conjunctiva
Definition: Amyloidosis of the conjunctiva may be primary or secondary. Primary localized deposition in the substantia propria occurs without systemic involvement. Secondary amyloidosis of the conjunctiva may occur in association with corneal involvement, or secondary to inflammation, or as part of a systemic condition such as multiple myeloma.
Incidence/Prevalence: This is a rare condition. Only small groups of patients have been reported. Some authors report an incidence of about .002% in surgical pathology material (1).
Etiology: The material deposited in primary amyloidosis of the conjunctiva is generally immunoglobulin-related proteins, amyloid light chains. IgD, IgA lamda have been described.
Clinical Findings: Primary amyloidosis of the conjunctiva occurs in young to middle aged adults as unilateral or bilateral (~20%) solitary or waxy, firm painless nodules or fusiform swellings. Ptosis may be present (~60%) with tarsal or levator involvement (number 1). Pain is present in about 20% of cases. There may be associated vascular dilation and hyperemia (number 2).
Histopathology: In hematoxylin and eosin stained sections, amyloid is viewed as nodular collections of amorphous homogenous eosinophilic deposits in the substantia propria (arrow 3)
and sometimes in the walls of blood vessels (arrow 4). There may be associated inflammation and even a foreign body giant cell response to the amyloid. When stained with the fluorescent Congo red dye and viewed under polarized light with a second polarizing analyzer, the amyloid deposits exhibit red-green dichroism (arrow 5), a result of several factors including retardation of birefringence, linear and circular dichroism, the Cotton effect and other influences (see more in depth discussion). Note in the photograph that some of the amyloid deposits appear green and other appear yellow, orange and even bright red. The multiple influences in some case are additive.
Treatment: Once the diagnosis of a primary localized process has been made by excluding systemic conditions that would warrant other therapy, debulking of the tumor is often performed with good success.
Prognosis: Only about 15% of the tumors progress; the others remain stable or regress.


1. Demrici et al: Survey Ophthalmology 2006;51:419-33.

2. Leibovitch et al. Ophthalmology 2006;113:1657-64.

What is a dentate pearl?

Dentate Pearl
Definition: degenerative lesion of the dentate process that is characterized by a nodule of calcification beneath the retina.
Incidence/Prevalence: Dentate pearls are commonly seen in autopsy eyes.
Clinical: Occasionally dentate pearls are seen clinically with scleral depression. The dentate pearl is considered a degenerative lesion and has absolutely no known clinical significance except that it should be recognized as such when observed.
Gross Pathology: Under the dissecting microscope the dentate pearl appears as a yellow, slightly opalescent, sphere (hence pearl) that is in the base of the dentate process (arrow 1). The dentate pearl is usually apparent near the base of the dentate process.
Histopathology: After sectioning the dentate pearl is a calcified sphere or nodule that is located beneath the surface retina and often beneath the retina and pigment epithelium (arrow 2).

What is spheroidal degeneration?

Spheroidal Degeneration is also known as Labrador keratopathy, Bietti nodular hyaline bandshaped keratopathy, climatic droplet keratopathy, proteinaceous corneal degeneration, elastotic degeneration, Fisherman’s keratopathy, and Eskimo’s corneal degeneration

Definition: Described in 1955 by Bietti, this relatively common condition features characteristic oil deposits at the limbus which are characterized histologically as mauve globular degeneration and are strongly associated with UV exposure.

Incidence/Prevalence: Typically, the lesions are associated with high UV exposure climates and/or reflected light such as observed in desert, ocean and snow. The incidence rises with age. Prevalence is 7% in areas of South Africa. The prevalence is higher in Greenland than Copenhagen.

Etiology: The theory is that UV exposure results in altered proteins depositing at the limbus. The proteins contain a high content of sulfur. Repeated arc welding burns may result in a similar condition.

Clinical Findings: 0.1-0.6 mm yellow oil droplets deposit near the limbus in the 3 and 9 o’clock positions in older individuals. Spheroidal degeneration is usually bilateral in the primary form. The areas may appear band shaped and often are associated with pingueculae but presumably and incredulously not pterygia!
Three types have been described:
1. primary corneal involvement
2. corneal involvement secondary to an underlying process such as a chronic infection
3. conjunctiva
Histopathology: Amorphous mauve colored globules are seen in the superficial corneal stroma or substantia propria close to the limbus in hematoxylin and eosin sections (number 2). The globules are often confluent. The globules are not dissolved by elastase. It is very easy to confuse these globules with calcification especially when they are in the cornea near Bowman's layer. However, careful examination shows that they lack the granular quality and deep purple color of calcium crystals but rather are amorphous centrally homogeneous deposits.

The globules may stain focally and usually peripherally with congo red (arrow 3). This may lead to misconclusions that the deposits are amyloid but there is no dichroism with polarized light (number 4). The birefringence seen in the photograph originates from keratin and collagen not the spheroidal degeneration nodules.

Autofluorescence (number 5) reveals bright fluorescence under ultraviolet light. The proteins of the globules contain a high sulfur content.

Treatment: Corneal involvement that affects vision has been treated by removal including procedures such as penetrating keratoplasty, without recurrence.