Corneal lipid degeneration refers to the abnormal deposition of lipids in the corneal stroma. It can be categorized into primary and secondary types. Primary lipid degeneration is rare, and its etiology remains unclear, though it may be associated with increased vascular permeability at the limbus. Secondary lipid degeneration is commonly seen in conditions leading to corneal neovascularization, such as corneal stromal keratitis, trauma, corneal edema, and corneal ulcers.
Clinically, it manifests as dense gray or yellowish-white lesions, often located in regions of neovascularization without inflammatory response. Lipid deposits align along the vasculature within the cornea, giving a fan-shaped appearance with feathered edges, and cholesterol crystals may be visible at the lesion margins. In rare cases, lipid degeneration can occur in regions of acute inflammation, typically presenting as dense, disc-shaped lesions.
Primary lipid degeneration is bilateral and may be located centrally, appearing as disc-shaped, dense lesions, or peripherally, resembling an expanded arcus senilis. In addition to cosmetic concerns, it may impair vision. The diagnosis of primary lipid degeneration requires the following criteria: no history of ocular trauma, absence of corneal neovascularization, no similar cases among family members, no systemic lipid metabolism disorders, and normal blood lipid levels. For cases of primary lipid degeneration with visual impairment, penetrating keratoplasty may be considered, although recurrence of lipid deposition on the graft has been reported postoperatively.
In secondary lipid degeneration caused by acute inflammation, lipid deposits generally resolve gradually over time. However, in cases of vision loss, penetrating keratoplasty may be considered.