Distortion Correction of OCT Images of the Crystalline Lens

Damian Siedlecki, Alberto de Castro, Enrique Gambra, Sergio Ortiz, David Borja, Stephen Uhlhorn, Fabrice Manns, Susana Marcos, Jean-Marie Parel
2012 Optometry and Vision Science  
Purpose. To propose a method to correct optical coherence tomography (OCT) images of posterior surface of the crystalline lens incorporating its gradient index (GRIN) distribution and explore its possibilities for posterior surface shape reconstruction in comparison to existing methods of correction. Methods. Two-dimensional images of nine human lenses were obtained with a time-domain OCT system. The shape of the posterior lens surface was corrected using the proposed iterative correction
more » ... . The parameters defining the GRIN distribution used for the correction were taken from a previous publication. The results of correction were evaluated relative to the nominal surface shape (accessible in vitro) and compared with the performance of two other existing methods (simple division, refraction correction: assuming a homogeneous index). Comparisons were made in terms of posterior surface radius, conic constant, root mean square, peak to valley, and lens thickness shifts from the nominal data. Results. Differences in the retrieved radius and conic constant were not statistically significant across methods. However, GRIN distortion correction with optimal shape GRIN parameters provided more accurate estimates of the posterior lens surface in terms of root mean square and peak values, with errors Ͻ6 and 13 m, respectively, on average. Thickness was also more accurately estimated with the new method, with a mean discrepancy of 8 m. Conclusions. The posterior surface of the crystalline lens and lens thickness can be accurately reconstructed from OCT images, with the accuracy improving with an accurate model of the GRIN distribution. The algorithm can be used to improve quantitative knowledge of the crystalline lens from OCT imaging in vivo. Although the improvements over other methods are modest in two dimension, it is expected that three-dimensional imaging will fully exploit the potential of the technique. The method will also benefit from increasing experimental data of GRIN distribution in the lens of larger populations. (Optom Vis Sci 2012;89:1-•••)
doi:10.1097/opx.0b013e3182508344 pmid:22466105 pmcid:PMC3348411 fatcat:k3mtdq5kyfb27ousphfqpu2cke