"In situ" corneal and contact lens thickness changes with high-resolution optical coherence tomography

To show the use of high-resolution spectral-domain optical coherence tomography (HR-SOCT) for the in situ evaluation of epithelial, stromal, and contact lens (CL) thickness changes under closed-eye conditions without lens removal.

Eight young healthy patients wore a thick soft CL for 90 minutes under closed-eye conditions, and measures of epithelial and stromal corneal thickness were obtained at regular intervals using a HR-SOCT (Copernicus HR; Optopol Tech. SA, Zawiercie, Poland).

Minimal changes in epithelial thickness were detected with a transient statistically significant increase in epithelial thickness in the fellow control eye 30 minutes after insertion (P = 0.028). A significant and progressive increase in stromal thickness up to 8% after 90 minutes of lens wear was observed at a constant rate of 2.5% every 30 minutes, being statistically significant in all observations (P < 0.001). Fellow control eyes also showed a significant increase in stromal thickness at a much lower rate of 0.5% every 30 minutes. Lens thickness decreased significantly by 2% after 90 minutes of lens wear under closed-eye conditions (P < 0.001). Individual analysis showed that all eyes displayed stromal swelling, whereas only half of them showed epithelial swelling.

Increase in stromal thickness and a slight decrease in lens thickness were observed in response to a hypoxic stimulus under closed-eye conditions. HR-SOCT is a powerful tool to investigate in vivo the physiological interactions between cornea and CLs.