The effect of successful contact lens wear on mucosal immunity of the eye.

OBJECTIVE

This study aimed to assess the effect of contact lens wear on the mucosal defenses of the outer eye against infection.

DESIGN

A case-controlled study of daily contact lens wearers in their initial 6 months of contact lens wear.

PARTICIPANTS

Contact lens wearers (mean age, 23.1 years; 47 subjects) were compared with age-matched control subjects (mean age, 24.7 years; 44 subjects).

INTERVENTION

Outer eye defenses were studied by assay of tear constituents and quantitative conjunctival microbiology.

MAIN OUTCOME MEASURES

Antimicrobial activity of tears was studied by assay of total immunoglobulin A (IgA), IgA isotype-specific antibodies reactive with Escherichia coli, Haemophilus influenzae, Staphylococcus epidermidis, albumin and lysozyme, and the ocular surface microbial load determined using quantitative microbiology of the conjunctival sac.

RESULTS

The IgA isotype-specific antibodies reactive with E. coli (P = 0.03) and S. epidermidis (P = 0.068) were lower in contact lens wearers, but antibody:albumin ratios were not significantly different in the two groups. Contact lens wear also had no significant effect on tear IgA, albumin, or lysozyme or its ratios with albumin. Bacterial numbers and colonization rates for coagulase-negative staphylococci were greater in contact lens wearers than in age-matched control subjects. Corynebacterium sp. and non-Enterobacteriaceae (P = 0.007) were isolated more frequently and in greater numbers from contact lens wearers. Colonization rates were increased for Corynebacterium sp., but non-Enterobacteriaceae were transient. In both daily contact lens wearers and age-matched control subjects, most conjunctival flora were transient rather than colonizing, and no subject developed an outer eye infection during the study.

CONCLUSION

These results suggest that daily contact lens wear does not significantly alter the mucosal defenses of the outer eye that function to eliminate organisms from the conjunctival sac and prevent outer eye infection.