[Changes of corneal limbus in long-term soft contact lens wearers by using laser confocal microscope]

To investigate corneal limbus changes in long-term soft contact lens wearers using laser confocal microscope.

All examinees were chosen from people who received pre-refractive surgery examination or regular physical examination in Department of Ophthalmology of Peking University First Hospital during October to November, 2004 and May to October, 2006. The contact lens wearer (CLW) group consisted of 22 eyes of 22 patients (age distribution, 23 - 50 years) with a history of refractive errors and more than ten-year soft contact lens wear. Thirty-eight eyes of 38 patients (age distribution, 18 - 52 years) with refractive errors but no history of contact lens wear were observed as the controls. After detailed examinations of slit lamp biomicroscopy, superior and inferior limbus were examined by laser confocal microscope. Corneal microstructure and cell morphology were analyzed, and cell densities were measured.

Images of corneal limbus could be observed clearly in both groups. The arrangement of limbal epithelium in CLW group showed irregular as compared to the control group. Epithelial microcystic changes and highly reflective dots among epithelium were found in CLW group which were not found in the control group. The Langerhans cell density of both superior limbus and inferior limbus in CLW group were higher than that of the control group (P < 0.05). There were highly reflective microdot deposits in the limbal corneal stroma in CLW group which were not appeared in the control group. Keratocyte density in anterior stroma of both superior and inferior limbus in CLW group was lower than that of the control group (P < 0.05). Keratocyte density in posterior stroma of both superior and inferior limbus in CLW group was lower than that of the control group (P < 0.05). The average stroma thickness of both superior and inferior limbus in CLW group was also lower than that of the control group (P < 0.05).

Long-term soft contact lens wear can induce many changes in corneal limbus, such as microcystic changes in epithelial cells, microdot deposits in corneal stroma, increase of Langerhans cell density and decrease of keratocyte density, etc.