It’s interesting to note that the primary ocular complications associated with corneal GP lenses most often occur outside of the boundaries of the contact lens, near the limbus (Figure 1).
3 O’clock and 9 O’clock Staining This is a peripheral corneal punctate staining at the 3 o’clock and 9 o’clock or the 4 o’clock and 8 o’clock positions. The shape and position of superficial punctate keratitis (SPK) is dependent on the lens design and its resting position on the cornea. While patients may be relatively asymptomatic, there is often an associated localized conjunctival hyperemia along the horizontal meridian. Staining at 3 o’clock and 9 o’clock rarely disappears spontaneously and, more often, increases in severity. The etiology of the staining may be mechanical (i.e., related to the lens design or fabrication) or physiological (i.e., related to peripheral corneal drying).
Vascularized Limbal Keratitis Vascularized limbal keratitis (VLK) is an elevated, vascularized, semi-opaque, epithelial/stromal lesion bridging the limbus. Patients are often the first to visualize the defect. The condition is often accompanied by conjunctival injection, peripheral corneal edema, and staining of the cornea, limbus, and conjunctiva. Patient symptoms include moderate discomfort with some photophobia and lacrimation and lens awareness with decreased lens wearing time. Following resolution of the lesions, an opaque peripheral scar may be present.
Conjunctival Xerosis This manifests as an elevated conjunctival lesion localized along the 180° (intrapalpebral space) meridian. The lesions are related to chronic drying of the bulbar conjunctiva and often take on a slight brownish color due to keratinization of the conjunctival epithelium. While patients are relatively asymptomatic, they often complain about the cosmetic appearance of the lesions and the associated conjunctival injection present toward the end of the day.
Dellen Dellen appear as localized, saucer-like depressions in the peripheral cornea. The depressions are related to localized dryness, resulting in epithelial/stromal dehydration. Dellen can occur in conjunction with 3 o’clock and 9 o’clock staining, and they may scar and become vascularized.
Foreign Body Tracking One of the few corneal complications that actually occurs beneath a corneal contact lens is foreign body tracking (a.k.a. foreign body staining). This is perhaps the single most common complication seen in individuals wearing corneal contact lenses. It occurs when a foreign particle finds its way beneath the lens, resulting in what patients often refer to as a “contact lens attack.”
With blinking, the foreign body rakes across the surface epithelium, resulting in a localized or diffuse corneal staining pattern (Figure 2). The foreign body is frequently self-expelled from beneath the lens by the rather significant reflex tearing induced by the semi-trapped foreign body. Because the residual defect frequently involves only the surface epithelium, the defects heal within hours, often without lens removal. Though relatively benign, these “contact lens attacks” are a frequent nuisance to corneal contact lens wearers. CLS