Neovascularization, Corneal, CL-related Clinical Presentation

Updated: Aug 19, 2015
  • Author: Barry A Weissman, OD, PhD, FAAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

Patients are almost always asymptomatic unless the central visual axis is involved.

Patients with CL-induced NV are often aphakic, report a history of sleeping or napping with their CLs on their eyes in an extended wear modality, or report many years of contact lens wear, especially with low oxygen permeability CLs.

Often, a history of poor compliance with proper CL wear (eg, wear extended intentionally or unintentionally through multiple sleep cycles) and care is present. Alternatively, the CLs may be "tight" (eg, restrict tear exchange) or may have low oxygen permeability (eg PMMA lenses or nonsilicone hydrogel CLs).

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Physical

Slit lamp biomicroscopy

NV can be observed in the cornea via slit lamp biomicroscopy. It can be seen in direct illumination or in retroillumination as a continuum of the limbal peripheral vessel arcades. Measuring both the extent and the depth of the corneal NV is important to assist in monitoring this disease. NV can be categorized based on its source (ie, conjunctival, limbal, iris), location, depth, length, branching pattern, color, leakage, and nature of blood flow (ie, presence of corneal hemorrhages). [21, 22]

Limbal hyperemia is the earliest sign of corneal neovascularization.

Superficial vessels emerge in the anterior stroma and appear as single or multiple (pannus) tortuous vessels under low magnification.

Deeper stromal vessels emerge through the cornea as straight vessels that arborize, occasionally accompanied by nerve fibers. They are generally anterior ciliary vessels, appear dark red, and do not raise the epithelium.

Active engorged vessels, occasionally surrounded by lipid exudates and exceeding 1-2 mm in length from the limbus, should raise concern. Active vessels appear bright in color and may have accompanying surrounding corneal edema and leakage.

Lipid deposition appears as yellow-white opacities at the leading edge or surrounding the stromal vessels.

Careful gonioscopy in eyes with deep NV rules out an iris angle choroidal tumor.

NV also should be differentiated at clinical examination from a conjunctival carcinoma extending onto the corneal epithelium.

Ghost vessels have no active blood circulation, represent old corneal neovascularization, and are no longer active.

Measurement of corneal sensation

Measurement of corneal sensation can be helpful in differentiating CL-related NV from a herpes simplex virus (HSV) keratitis (typically reduced sensation with HSV).

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Causes

All CLs (although less so with silicone CLs) can cause NV. This includes daily and extended-wear types of any hydrogel, hard (PMMA), and rigid gas permeable CLs (including orthokeratology CLs) and scleral lenses. NV primarily is related to corneal hypoxia from CL wear and/or chronic corneal desiccation associated with the edges or rigid lenses.

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