Quantification of corneal transparency in post-mortem human corneas using laser scatter image analysis

The cornea is a highly transparent structure covering the anterior one-fifth of the eyeball. The suitability of post-mortem donor corneas for keratoplasty is currently qualitatively assessed. This makes inferences prone to bias and subjective variability. This study aimed to develop a simple, feasible and cost-effective method to quantify corneal transparency.

An artificial anterior chamber was modified to provide a central transparent passage and a standardised pressure segment. All corneas graded 'fair' were included in this study. The corneoscleral buttons were mounted on the modified artificial anterior chamber. The mounted chamber was held in a horizontal position at a fixed distance from a white projection screen. The laser source was placed in alignment with an artificial anterior chamber so that it passed through the centre of the cornea. A camera mounted on a tripod stand was placed at a prefixed distance. An image of the scattered laser spot that formed after the laser passed through the mounted cornea on the screen was captured with a single digital camera and standardised settings. Image analysis was performed using ImageJ, an open platform for scientific image analysis. The average red pixel intensity, max intensity, and full-width half max were calculated.

The average red intensity was 132.45 ± 6.65 SD. The mean for max intensity was 51.1 ± 3.78 SD and the full-width half max 787.7 ± 84.7 SD.

Laser quantification is a simple and cost-effective method of quantifying corneal transparency. The study lends proof to the principle involved.