Contact lens overwear syndromes can take several forms. Hypoxia, lactate accumulation, and impaired carbon dioxide efflux are responsible for these complications.
Table 5-10 Contact Lens–Related Problems and Complications
Figure 5-16 Contact lens complications. A, Pseudomonas corneal ulcer. B, Corneal neovascularization (vascular pannus). C, Giant papillary conjunctivitis. D, Sterile corneal infiltrates.
(Parts C and D courtesy of Deborah S. Jacobs, MD.)
Central epithelial edema (Sattler veil) may present after many hours of wear, more commonly with hard contact lenses. This epithelial edema causes blurred vision that may persist for many hours or, in rare instances, progress to acute epithelial necrosis.
Microcystic epitheliopathy, another condition caused by impaired metabolism in the corneal epithelium, shows fine epithelial cysts, which are most easily observed with retroillumination. This condition is more common with extended wear. The cysts may either be asymptomatic or cause recurrent brief episodes of pain and epiphora. It takes up to 6 weeks following discontinuation of contact lens wear for the cysts to resolve. In some cases, this epitheliopathy may have a dendritic appearance.
Corneal neovascularization (Fig 5-16B) is usually a sign of hypoxia. Refitting with lenses of higher-oxygen-permeability material or with a looser fit, requiring fewer hours of lens wear per day, or switching to disposable lenses can prevent further progression. If neovascularization is extensive, it can lead to corneal scarring and lipid deposition or intracorneal hemorrhage. Superficial pannus is rarely associated with RGP contact lens wear, but is encountered more frequently in patients who use soft lenses either as extended wear or daily wear with less frequent replacement. This type of neovascularization is probably caused by hypoxia and chronic trauma to the limbus. Other causes of pannus, such as staphylococcal and chlamydial keratoconjunctivitis, should be considered in the presence of accompanying signs that suggest them.
Deep stromal neovascularization has been associated with extended-wear contact lenses, especially in aphakia. This condition is not usually symptomatic unless there is secondary lipid deposition. Deep neovascularization of the cornea is often irreversible and is best managed by discontinuing contact lens wear.
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.