Abstract
Purpose: :
Keratoconus is a progressive, bilateral, and non-inflammatory disease of the cornea. The standard of care for this disease is to provide spectacles initially, progress to rigid-gas-permeable contact lenses, then likely a penetrating keratoplasty. Recently, collagen crosslinking using ultraviolet A (UVA) and riboflavin as a photosensitizer has been suggested as a new treatment, increasing the biomechanical strength of the human cornea. In this study, we investigated the rigidity of the human cornea before and after UVA/riboflavin treatment.
Methods: :
Ten human corneas were obtained and mounted on an artificial anterior chamber. The corneal epithelium was removed. The anterior chamber was then connected to a flow modulator and mounted on a platform underneath a laser/detector apparatus. The computer parameters were set for a high intra-ocular pressure (IOP) of 57mmHg and a low of 5.7mmHg with a cycle every ten seconds. Measurements of the deflection of the corneal apex were obtained continuously over 10 minutes. Ricolin riboflavin solution was then administered according to manufacturer guidelines. The Vega UV illumination system was used to irradiate the cornea for 30 minutes according to manufacturer guidelines. The ultraviolet-A irradiation (370nm) was applied 1.0cm from the cornea with a surface irradiance of 3mW/cm(2). The cornea was washed with BSS and blot dried. The measurements were obtained again as noted above.
Results: :
The input pressure as well was the corresponding corneal apex displacement were measured. This cycled 6 times per minute and was recorded over 10 minutes. A plot was obtained comparing the input pressure with the corresponding corneal apical displacement. Linear regression analysis was performed and the rate of apical displacement change versus IOP was obtained prior to and following treatment. 8 of the 10 corneas demonstrated less displacement over the pressure range after treatment when compared to before treatment. Additionally, it was noted that the variation of displacement corresponding to a given pressure decreased after treatment.
Keywords: cornea: clinical science • keratoconus • cornea: stroma and keratocytes