A comparative study of corneal endothelial changes induced by different durations of soft contact lens wear

To analyze the effect on the morphologic characteristics of the corneal endothelium of the duration of soft contact lens wearing periods.

Ninety soft contact lens wearers were divided into three groups: short-term users, for less than 5 years (n=60 eyes); intermediate-term users, from 6 years to 10 years (n=60); longterm users, for more than 10 years (n=60). Thirty non-contact lens wearers (60 eyes) were included as controls. All eyes were examined with a specular microscope. Analysis of covariance was used to detect any differences among the controls and the various soft contact lens subgroups.

There was a significant correlation between duration of soft contact lens use and morphologic changes of corneal endothelium. All soft contact lens subgroups had a significantly greater coefficient of variation in cell size than non-contact lens users . The proportion of hexagonal cells and the mean corneal endothelial cell density in those using soft contact lenses for more than 6 years were significantly lower than in the control group . Soft contact lens wear was significantly correlated with decreasing corneal endothelial cell densities with time.

The coefficient of variation in cell size may be a sensitive indicator of early morphologic changes of the corneal endothelium. As the decrease in cell density among the contact lens subgroups was significantly associated with the duration of soft contact lens wearing periods, it will be useful to investigate endothelial cell density for evaluation of corneal endothelial function concerned with contact lens wearing.