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Peripheral Corneal Disease
Key Concepts
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The peripheral cornea’s proximity to the limbus and conjunctival lymphoid tissue predisposes it to unique pathologies that are distinct from the avascular central cornea.
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The peripheral cornea is particularly susceptible to inflammation related to systemic autoimmune diseases, including rheumatoid arthritis, granulomatosis with polyangiitis, inflammatory bowel disease, polyarteritis nodosa, and others.
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Management of peripheral corneal ulceration is usually dependent on treating the underlying systemic inflammatory disorder.
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Marginal keratitis and phlyctenular lesions of the peripheral cornea are thought to arise as a result of a hypersensitivity reaction to certain antigens.
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Mooren ulcer is a progressive, painful, and often bilateral peripheral ulceration without a history of systemic inflammatory disorder. It is often difficult to manage, resulting in poor visual outcomes.
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Neoplastic processes may first manifest in the peripheral cornea and limbus.
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Degenerative conditions may affect the peripheral cornea; in the cases of corneal arcus and calcific band keratopathy, they may indicate a systemic abnormality.
The Peripheral Cornea: Susceptibility and Response to Disease
The peripheral cornea is generally considered to be that portion located between the central 50% of the cornea and the limbus. This is the thickest region of the cornea and is directly adjacent to the corneal limbus and internal angle structures. Although the peripheral cornea manifests some of the same disorders as the central cornea, its proximity to the limbus and conjunctiva results in a unique collection of abnormalities. These frequently stem from the distinctive architecture of the limbus, which includes a highly vascular zone with associated lymphatic tissue, scleral collagen, corneal collagen, and limbal stem cells. Thus vascular inflammatory disorders, limbal infections, collagen vascular disorders, neoplastic disease, and local degenerations may affect the peripheral cornea in distinctive ways.
This chapter discusses peripheral corneal diseases by categorizing them into five groups: (1) congenital/developmental/inherited, (2) inflammatory/autoimmune, (3) neoplastic, (4) environmental exposure/degenerative/iatrogenic, and (5) infectious ( Table 19.1 ). A number of these disorders could be classified under more than one heading; however, a single heading was chosen to reduce redundancy. To reduce further redundancy, this chapter includes an abbreviated discussion of each topic. If further information is desired, the reader can refer to the specific chapters concerning each disorder.
TABLE 19.1
Classification of Peripheral Corneal Disorders
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