Presbyopia is the age related, gradual loss of accommodation, mainly due to changes in the crystalline lens.
As part of research efforts to understand and cure this condition, ex vivo, cross-sectional OCT images of
crystalline lenses were obtained and analyzed to extract their physical and optical properties. The raw OCT
images are distorted, as the probing beam passing through media of different refractive indices and
refraction on curved surfaces. In a first step, various filters, edge detection and pattern matching methods
are applied to isolate the edge contour. An ellipse is fitted to the lens outline to obtain central reference
point for transforming the pixel data into the analysis coordinate system. This allows for the fitting of high
order equation to obtain a mathematical description of the edge contour, which obeys constraints of
continuity as well as zero to infinite surface slopes from apex to equator. Robustness of these algorithms
are tested by analyzing the images at various contrast levels. Gradient refractive index of the lens is
determined and the physical shape is reconstructed. In a further refinement, the refraction on the curved
anterior surface is compensated to obtain the actual shape of the posterior surface. Once the physical shape
is fully reconstructed, the optical properties are determined by fitting conic sections to both surfaces and
calculating the power profile across the lens. The relative contribution of each of these refinement steps is
investigated by comparing their influence on the effective power of the lens.