Microvascular abnormalities in the bulbar conjunctiva of contact lens users

Soft contact lenses are commonly used to improve vision acuity or in cosmetic enhancement. We hypothesize that contact lens use can cause inadvertent damage to either the conjunctival microcirculation via direct vasoocclusion when the lens physically interacts with or damages the underlying vessels, or to the bulbar conjunctiva itself when the lens rests unevenly on the surface of the bulbar conjunctiva. Computer-assisted intravital microscopy was utilized to document (via video recording) and objectively quantify (via image analysis) real-time microvascular abnormalities resulting from changes and vessel remodeling in the conjunctival microcirculation in long-term (>2 yrs) contact lens users (n = 102), with non-users serving as control subjects (n = 29). A severity index (SI)-computed as the arithmetic sum of the abnormalities found in the conjunctival microcirculation in each contact lens user-was established for objective comparison with control subjects and critical interpretation. Contact lens user SI was significantly higher than control SI (user = 6.21 +/- 1.26; control = 2.31 +/- 1.49; p < 0.05), indicative of severe vasculopathy arising from contact lens use. The users also had significantly wider conjunctival vessel diameter (user = 71.25 +/- 12.09 mu m; control = 52.20 +/- 5.10 mu m; p < 0.05). Additional abnormalities, including damaged vessels, hemosiderin deposits (from damaged vessels or injury to the surface of the bulbar conjunctiva), vessel sludging, intermittent blood flow, and vessel tortuosity were commonly found in or adjacent to locations where the contact lens physically rested on the underlying conjunctival vessels. These results strongly suggest that microvascular abnormalities and remodeling changes occurred as a result of the inadvertent physical interaction of the lenses with either the underlying conjunctival vessels or the surface of the bulbar conjunctiva in contact lens users.